Engine Mechanical - 3.6l (Lfx) - Diagnostic Information and Procedures

Strategy Based Diagnostics

Perform a «Diagnostic System Check - Vehicle»(/cadillac/ats/i-2012-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) before using the symptom tables, if applicable.
Review the system operations in order to familiarize yourself with the system functions. Refer to «Disassembled Views»(/cadillac/ats/i-2012-2014/remont/mechanical/#engine-mechanical-36l-lfx-component-locator) , «Engine Component Description (LFX)»(/cadillac/ats/i-2012-2014/remont/mechanical/#engine-mechanical-36l-lfx-description-and-operation__engine-component-description-lfx) , «Drive Belt System Description»(/cadillac/ats/i-2012-2014/remont/mechanical/#engine-mechanical-36l-lfx-description-and-operation__drive-belt-system-description) , and «Lubrication Description»(/cadillac/ats/i-2012-2014/remont/mechanical/#engine-mechanical-36l-lfx-description-and-operation__lubrication-description) .

All diagnosis on a vehicle should follow a logical process. Strategy based diagnostics is a uniform approach for repairing all systems. The diagnostic flow may always be used in order to resolve a system problem. The diagnostic flow is the place to start when repairs are necessary. For a detailed explanation, refer to Strategy Based Diagnosis .

Visual/Physical Inspection

Inspect for aftermarket devices which could affect the operation of the engine. Refer to «Checking Aftermarket Accessories»(/cadillac/ats/i-2012-2014/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__checking-aftermarket-accessories) .
Inspect the easily accessible or visible system components for obvious damage or conditions which could cause the symptom.
Check for the correct oil level, proper oil viscosity, and correct filter application.
Verify the exact operating conditions under which the concern exists. Note factors such as engine RPM, ambient temperature, engine temperature, amount of engine warm-up time, and other specifics.
Compare the engine sounds, if applicable, to a known good engine and make sure you are not trying to correct a normal condition.

Intermittent

Test the vehicle under the same conditions that the customer reported in order to verify the system is operating properly.

Symptom List

Refer to a symptom diagnostic procedure from the following list in order to diagnose the symptom

«Base Engine Misfire without Internal Engine Noises»(/cadillac/ats/i-2012-2014/remont/mechanical/#engine-mechanical-36l-lfx-diagnostic-information-and-procedures__base-engine-misfire-without-internal-engine)
«Base Engine Misfire with Abnormal Internal Lower Engine Noises»(/cadillac/ats/i-2012-2014/remont/mechanical/#engine-mechanical-36l-lfx-diagnostic-information-and-procedures__base-engine-misfire-with-abnormal-internal)
«Base Engine Misfire with Abnormal Valve Train Noise»(/cadillac/ats/i-2012-2014/remont/mechanical/#engine-mechanical-36l-lfx-diagnostic-information-and-procedures__base-engine-misfire-with-abnormal-valve)
«Base Engine Misfire with Coolant Consumption»(/cadillac/ats/i-2012-2014/remont/mechanical/#engine-mechanical-36l-lfx-diagnostic-information-and-procedures__base-engine-misfire-with-coolant-consumption)
«Base Engine Misfire with Excessive Oil Consumption»(/cadillac/ats/i-2012-2014/remont/mechanical/#engine-mechanical-36l-lfx-diagnostic-information-and-procedures__base-engine-misfire-with-excessive-oil)
«Engine Noise on Start-Up, but Only Lasting a Few Seconds»(/cadillac/ats/i-2012-2014/remont/mechanical/#engine-mechanical-36l-lfx-diagnostic-information-and-procedures__engine-noise-on-start-up-but-only)
«Upper Engine Noise, Regardless of Engine Speed»(/cadillac/ats/i-2012-2014/remont/mechanical/#engine-mechanical-36l-lfx-diagnostic-information-and-procedures__upper-engine-noise-regardless-of-engine)
«Lower Engine Noise, Regardless of Engine Speed»(/cadillac/ats/i-2012-2014/remont/mechanical/#engine-mechanical-36l-lfx-diagnostic-information-and-procedures__lower-engine-noise-regardless-of-engine)
«Engine Noise Under Load»(/cadillac/ats/i-2012-2014/remont/mechanical/#engine-mechanical-36l-lfx-diagnostic-information-and-procedures__engine-noise-under-load)
«Engine Will Not Crank - Crankshaft Will Not Rotate»(/cadillac/ats/i-2012-2014/remont/mechanical/#engine-mechanical-36l-lfx-diagnostic-information-and-procedures__engine-will-not-crank-crankshaft)
«Engine Compression Test»(/cadillac/ats/i-2012-2014/remont/mechanical/#engine-mechanical-36l-lfx-diagnostic-information-and-procedures__engine-compression-test)
«Oil Consumption Diagnosis»(/cadillac/ats/i-2012-2014/remont/mechanical/#engine-mechanical-36l-lfx-diagnostic-information-and-procedures__oil-consumption-diagnosis)
«Oil Pressure Diagnosis and Testing»(/cadillac/ats/i-2012-2014/remont/mechanical/#engine-mechanical-36l-lfx-diagnostic-information-and-procedures__oil-pressure-diagnosis-and-testing)
«Oil Leak Diagnosis»(/cadillac/ats/i-2012-2014/remont/mechanical/#engine-mechanical-36l-lfx-diagnostic-information-and-procedures__oil-leak-diagnosis)

Base Engine Misfire without Internal Engine Noises

Cause	Correction
Abnormalities, severe cracking, bumps, or missing areas, in the accessory drive belt Abnormalities in the accessory drive system and/or components may cause engine RPM variations and lead to a misfire DTC. A misfire code may be present without an actual misfire condition.	Replace the drive belt. Refer to Drive Belt Replacement .
Worn, damaged, or mis-aligned accessory drive components or excessive pulley runout may lead to a misfire DTC. A misfire code may be present without an actual misfire condition.	Inspect the components: Repair or replace as required.
Loose or improperly installed engine flywheel or crankshaft balancer A misfire code may be present without an actual misfire condition.	Repair or replace the flywheel and/or balancer as required. Refer to Automatic Transmission Flex Plate Replacement , or Crankshaft Balancer Replacement .
Restricted exhaust system A severe restriction in the exhaust flow can cause significant loss of engine performance and may set a DTC. Possible causes of restrictions include collapsed or dented pipes or plugged mufflers and/or catalytic converters.	Repair or replace as required.
Improperly installed or damaged vacuum hoses	Repair or replace as required.
Improper sealing between the intake manifold and cylinder heads, intake manifold and plenum duct, plenum duct and water crossover, water crossover and throttle body and/or pressure relief valve and intake manifold.	Replace the intake manifold, plenum duct, gaskets, cylinder heads, throttle body and/or pressure relief valve as required.
Improperly installed or damaged MAP sensor and/or seal The sealing grommet of the MAP sensor should not be torn or damaged.	Repair or replace the MAP sensor as required.
Improperly installed or damaged EVAP purge solenoid and/or O-ring seal	Repair or replace the EVAP purge solenoid as required.
Worn or loose followers, valve rocker arms The follower, valve rocker arm, roller bearing should be intact and in the proper position	Replace the followers, valve rocker arms, as required.
Stuck valves Carbon buildup on the valve stem can cause the valve not to close properly.	Repair or replace as required.
Excessively worn or mis-aligned timing chain or chains	Replace the timing chain or chains and sprockets as required.
Worn camshaft lobes	Replace the camshaft or camshafts and SHLAs, valve lifters.
Excessive oil pressure A lubrication system with excessive oil pressure may lead to excessive valve lifter pump-up and loss of compression.	Perform an oil pressure test. Refer to Oil Pressure Diagnosis and Testing . Repair or replace the oil pump as required.
Faulty cylinder head gaskets and/or cracking or other damage to the cylinder heads and engine block cooling system passages. Refer to Diagnostic Starting Point - Vehicle . Coolant consumption may or may not cause the engine to overheat.	Inspect for spark plugs saturated by coolant. Refer to Spark Plug Inspection . Inspect the cylinder heads, engine block, and/or head gaskets. Repair or replace as required.
Worn piston rings Oil consumption may or may not cause the engine to misfire.	Inspect the spark plugs for oil deposits. Refer to Spark Plug Inspection . Inspect the cylinders for a loss of compression. Refer to Engine Compression Test . Perform cylinder leak down and compression testing to identify the cause. Repair or replace as required.
A damaged crankshaft reluctor wheel A damaged crankshaft reluctor wheel can result in different symptoms depending on the severity and location of the damage. Systems with SEVERE reluctor ring damage may exhibit periodic loss of crankshaft position, stop delivering a signal, and then re-sync the crankshaft position. Systems with SLIGHT reluctor ring damage may exhibit no loss of crankshaft position and no misfire may occur. However, a P0300 DTC may be set.	Replace the crankshaft as required.

Base Engine Misfire without Internal Engine Noises

Base Engine Misfire with Abnormal Internal Lower Engine Noises

Cause	Correction
Abnormalities, severe cracking, bumps or missing areas, in the accessory drive belt Abnormalities in the accessory drive system and/or components may cause engine RPM variations, noises similar to a faulty lower engine and also lead to a misfire condition. A misfire code may be present without an actual misfire condition.	Replace the drive belt. Refer to Drive Belt Replacement .
Worn, damaged, or mis-aligned accessory drive components or excessive pulley runout A misfire code may be present without an actual misfire condition.	Inspect the components, repair or replace as required.
Loose or improperly installed engine flywheel or crankshaft balancer A misfire code may be present without an actual misfire condition.	Repair or replace the engine flywheel and/or crankshaft balancer as required. Refer to Automatic Transmission Flex Plate Replacement , or Crankshaft Balancer Replacement .
Worn or broken piston rings Oil consumption may or may not cause the engine to misfire.	Inspect the spark plugs for oil deposits. Refer to Spark Plug Inspection . Inspect the cylinders for a loss of compression. Refer to Engine Compression Test . Perform cylinder leak down and compression testing to determine the cause. Repair or replace as required.
Worn crankshaft thrust bearings Severely worn thrust surfaces on the crankshaft and/or thrust bearing may permit fore and aft movement of the crankshaft and create a DTC without an actual misfire condition.	Replace the crankshaft and bearings as required.

Base Engine Misfire with Abnormal Internal Lower Engine Noises

Base Engine Misfire with Abnormal Valve Train Noise

Cause	Correction
Worn or loose followers, valve rocker arms The follower, valve rocker arm, roller bearing should be intact and in the proper position.	Replace the followers, valve rocker arms, as required.
Stuck valves Carbon buildup on the valve stem can cause the valve not to close properly.	Repair or replace as required.
Excessively worn or mis-aligned timing chain or chains	Replace the timing chain or chains and sprockets as required.
Worn camshaft lobes	Replace the camshaft or camshafts and SHLAs (valve lifters).
Sticking SHLAs (lifters)	Replace the SHLAs as required.

Base Engine Misfire with Abnormal Valve Train Noise

Base Engine Misfire with Coolant Consumption

Cause	Correction
Faulty cylinder head gaskets and/or cracking or other damage to the cylinder heads and engine block cooling system passages. Refer to Diagnostic Starting Point - Vehicle . Coolant consumption may or may not cause the engine to overheat.	Inspect for spark plugs saturated by coolant. Refer to Spark Plug Inspection . Perform a cylinder leak down test. Inspect the cylinder heads and engine block for damage to the coolant passages and/or a faulty head gasket. Repair or replace as required.

Base Engine Misfire with Coolant Consumption

Base Engine Misfire with Excessive Oil Consumption

Cause	Correction
Worn valves, valve guides and/or valve stem oil seals	Inspect the spark plugs for oil deposits. Refer to Spark Plug Inspection . Repair or replace as required.
Worn piston rings Oil consumption may or may not cause the engine to misfire.	Inspect the spark plugs for oil deposits. Refer to Spark Plug Inspection . Inspect the cylinders for a loss of compression. Refer to Engine Compression Test . Perform cylinder leak down and compression testing to determine the cause. Repair or replace as required.

Base Engine Misfire with Excessive Oil Consumption

Engine Noise on Start-Up, but Only Lasting a Few Seconds

Cause	Correction
Incorrect oil filter without anti-drainback feature	Install the correct oil filter.
Incorrect oil viscosity	Drain the engine oil and replace with the correct viscosity oil.
High stationary hydraulic lash adjuster (SHLA), valve lifter, leak down rate	Replace the SHLAs, valve lifters, as required.
Worn crankshaft thrust bearing	Inspect the thrust bearing and crankshaft. Repair or replace as required.
Damaged or faulty oil filter by-pass valve	Inspect the oil filter by-pass valve for proper operation. Repair or replace as required.

Engine Noise on Start-Up, but Only Lasting a Few Seconds

Upper Engine Noise, Regardless of Engine Speed

Cause	Correction
Low oil pressure	Perform an oil pressure test. Refer to Oil Pressure Diagnosis and Testing . Repair or replace as required.
Loose and/or worn follower, valve rocker arm	Inspect the follower, valve rocker arm. Repair or replace as required.
Improper lubrication to the followers, valve rocker arms	Inspect the following components, and repair or replace as required: The follower, valve rocker arm The SHLA, valve lifter The oil filter bypass valve The oil pump and pump screen The cylinder head oil galleries The engine block oil galleries
Broken valve spring	Replace the valve spring.
Worn or dirty stationary hydraulic lash adjusters (SHLAs), valve lifters	Replace the SHLAs, valve lifters.
Stretched or broken timing chain or chains and/or damaged sprocket teeth	Replace the timing chain or chains and sprockets.
Worn timing chain tensioner or tensioners	Replace the timing chain tensioner or tensioners as required.
Worn timing chain shoe or shoes	Replace the timing chain shoe or shoes as required.
Worn timing chain guide or guides	Replace the timing chain guide or guides as required.
Worn engine camshaft lobes	Inspect the engine camshaft lobes. Replace the camshaft or camshafts and SHLAs, valve lifters, as required.
Worn valve guides or valve stems	Inspect the following components, and repair as required: The valves The valve guides
Stuck valves Carbon on the valve stem or valve seat may cause the valve to stay open	Inspect the following components, and repair as required: The valves The valve guides

Upper Engine Noise, Regardless of Engine Speed

Lower Engine Noise, Regardless of Engine Speed

Cause	Correction
Low oil pressure	Perform an oil pressure test. Refer to Oil Pressure Diagnosis and Testing . Repair or replace damaged components as required.
Worn accessory drive components Abnormalities such as severe cracking, bumps or missing areas in the accessory drive belt and/or misalignment of system components.	Inspect the accessory drive system. Repair or replace as required.
Loose or damaged crankshaft balancer	Inspect the crankshaft balancer. Repair or replace as required.
Detonation or spark knock	Verify the correct operation of the ignition controls system. Refer Symptoms - Engine Controls .
Loose torque converter bolts	Inspect the torque converter bolts and engine flywheel. Repair or replace as required.
Loose or damaged engine flywheel	Repair or replace the engine flywheel.
Damaged oil pan, contacting the oil pump screen An oil pan that has been damaged may improperly position the oil pump screen, preventing proper oil flow to the oil pump.	Inspect the oil pan. Inspect the oil pump screen. Repair or replace as required.
Oil pump screen loose, damaged or restricted	Inspect the oil pump screen. Repair or replace as required.
Excessive piston-to-cylinder bore clearance	Inspect the piston and cylinder bore. Repair as required.
Excessive piston pin-to-bore clearance	Inspect the piston, piston pin, and the connecting rod. Repair or replace as required.
Excessive connecting rod bearing clearance	Inspect the following components, and repair as required: The connecting rod bearings The connecting rods The crankshaft The crankshaft journals
Excessive crankshaft bearing clearance	Inspect the following components, and repair as required: The crankshaft bearings The crankshaft journals
Incorrect piston, piston pin and connecting rod installation Pistons must be installed with the mark or dimple on the top of the piston facing the front of the engine. Piston pins must be centered in the connecting rod pin bore.	Verify the pistons, piston pins and connecting rods are installed correctly. Repair as required.

Lower Engine Noise, Regardless of Engine Speed

Engine Noise Under Load

Cause	Correction
Low oil pressure	Perform an oil pressure test. Refer to Oil Pressure Diagnosis and Testing . Repair or replace as required.
Detonation or spark knock	Verify the correct operation of the ignition controls. Refer to Symptoms - Engine Controls .
Loose torque converter bolts	Inspect the torque converter bolts and engine flywheel. Repair as required.
Cracked engine flywheel	Inspect the engine flywheel and bolts. Repair as required.
Excessive connecting rod bearing clearance	Inspect the following components, and repair as required: The connecting rod bearings The connecting rods The crankshaft
Excessive crankshaft bearing clearance	Inspect the following components, and repair as required: The crankshaft bearings The crankshaft journals The cylinder block crankshaft bearing bore

Engine Noise Under Load

Engine Will Not Crank - Crankshaft Will Not Rotate

Cause	Correction
Seized accessory drive system component	Remove the accessory drive belt or belts. Rotate the crankshaft by hand at the crankshaft balancer or the engine flywheel location. Repair or replace as required.
Hydraulically locked cylinder Coolant/antifreeze in cylinder Oil in cylinder Fuel in cylinder	Remove the spark plugs and check for fluid. Inspect for broken head gasket or gaskets. Inspect for cracked engine block or cylinder head. Inspect for a sticking fuel injector. Repair or replace as required.
Seized automatic transmission torque converter	Remove the torque converter bolts. Rotate the crankshaft by hand at the crankshaft balancer or the engine flywheel location. Repair or replace as required.
Material in cylinder Broken valve Piston material Foreign material	Inspect the cylinder for damaged components and/or foreign materials. Repair or replace as required.
Seized crankshaft or connecting rod bearings	Inspect the crankshaft and the connecting rod bearings. Repair as required.
Bent or broken connecting rod	Inspect the connecting rods. Repair as required.
Broken crankshaft	Inspect the crankshaft. Repair as required.
Seized or broken camshaft	Inspect the camshaft or camshafts. Inspect the cylinder head camshaft journals for damage. Repair as required.
Seized or broken balance shaft	Inspect the balance shaft. Inspect the block for damaged balance shaft bearings. Repair as required.
Seized or broken camshaft timing components	Inspect the following sprockets: The crankshaft sprocket The exhaust sprockets The intake sprockets Inspect the following chains: The primary camshaft drive chain The secondary camshaft drive chains Inspect the following guides: The lower primary camshaft drive chain guide The upper primary camshaft drive chain guides Inspect the secondary camshaft drive chain shoe. Inspect the following tensioners: The primary camshaft drive chain tensioner The secondary camshaft drive chain tensioners Repair as required.
Seized or broken valve train components	Inspect the followers, rocker arms. Inspect the lifters. Inspect the valves. Inspect the valve springs. Repair as required.

Engine Will Not Crank - Crankshaft Will Not Rotate

Coolant in Combustion Chamber

Cause	Correction
DEFINITION: Excessive white smoke and/or coolant type odor coming from the exhaust pipe may indicate coolant in the combustion chamber. Low coolant levels, an inoperative cooling fan, or a faulty thermostat may lead to an "overtemperature" condition which may cause engine component damage. A slower than normal cranking speed may indicate coolant entering the combustion chamber. Refer to Engine Will Not Crank - Crankshaft Will Not Rotate . Remove the spark plugs and inspect for spark plugs saturated by coolant or coolant in the cylinder bore. Inspect by performing a Cylinder Leakage Test . During this test, excessive air bubbles within the coolant may indicate a faulty gasket or damaged component. Inspect by performing a cylinder compression test. Two cylinders "side-by-side" on the engine block, with low compression, may indicate a failed cylinder head gasket. Refer to Engine Compression Test .
Cracked intake manifold or failed gasket	Replace the components as required.
Faulty cylinder head gasket	Replace the head gasket and components as required. Refer to Cylinder Head Cleaning and Inspection , and Cylinder Head Replacement - Left Side , or Cylinder Head Replacement - Right Side .
Warped cylinder head	Machine the cylinder head to the proper flatness, if applicable and replace the cylinder head gasket. Refer to Cylinder Head Cleaning and Inspection .
Cracked cylinder head	Replace the cylinder head and gasket.
Cracked cylinder liner or engine block	Replace the components as required.
Cylinder head or engine block porosity	Replace the components as required.

Coolant in Combustion Chamber

Coolant in Engine Oil

Cause	Correction
DEFINITION: Foamy or discolored oil or an engine oil "overfill" condition may indicate coolant entering the engine crankcase. Low coolant levels, an inoperative cooling fan, or a faulty thermostat may lead to an "overtemperature" condition which may cause engine component damage. Contaminated engine oil and oil filter should be changed. Inspect the oil for excessive foaming or an overfill condition. Oil diluted by coolant may not properly lubricate the crankshaft bearings and may lead to component damage. Refer to Lower Engine Noise, Regardless of Engine Speed . Inspect by performing a Cylinder Leakage Test . During this test, excessive air bubbles within the cooling system may indicate a faulty gasket or damaged component. Inspect by performing a cylinder compression test. Two cylinders "side-by-side" on the engine block with low compression may indicate a failed cylinder head gasket. Refer to Engine Compression Test .
Faulty external engine oil cooler	Replace the components as required.
Faulty cylinder head gasket	Replace the head gasket and components as required. Refer to Cylinder Head Cleaning and Inspection , and Cylinder Head Replacement - Left Side , or Cylinder Head Replacement - Right Side .
Warped cylinder head	Machine the cylinder head to proper flatness, if applicable, and replace the cylinder head gasket. Refer to Cylinder Head Cleaning and Inspection .
Cracked cylinder head	Replace the cylinder head and gasket.
Cracked cylinder liner or engine block	Replace the components as required.
Cylinder head, block, or manifold porosity	Replace the components as required.

Coolant in Engine Oil

Engine Compression Test

Special Tools

EN-39313 Spark Plug Port Adapter

For equivalent regional tools, refer to Special Tools .

A compression pressure test of the engine cylinders determines the condition of the piston rings, the valves and the head gaskets.

Run the engine until it reaches normal operating temperature. The battery must be at or near full charge. You may wish to connect a battery charger for the duration of the test to maintain an adequate battery level.
Turn the engine OFF.
Remove the intake manifold cover.
Remove the ignition coils and spark plugs from all cylinders. Refer to «Ignition Coil Replacement - Bank 1»(/cadillac/ats/i-2012-2014/remont/testing-diagnostics/#engine-controlsfuel-36l-lfx-repair-instructions) , and «Ignition Coil Replacement - Bank 2»(/cadillac/ats/i-2012-2014/remont/testing-diagnostics/#engine-controlsfuel-36l-lfx-repair-instructions) .
Connect the GDS2 to the vehicle and select "Compression Test". Enabling the Compression Test will disable the fuel pump, fuel injectors, and spark. The throttle body is opened to a Wide Open Throttle (WOT) position. The GDS2 will also automatically control the cranking procedure for many applications. If cranking control is not available use a remote start switch in place of the Starter Relay to control cranking.
Measure the engine compression, using the following procedure: Thread the EN-39313 adapter into the spark plug hole. Thread the compression gauge into the EN-39313 adapter. Enable cranking via the GDS2 or remote start switch. Record the reading after the cranking cycle completes. When the compression measurement is normal, the compression builds up quickly and evenly to the specified compression on each cylinder. Repeat the compression test for each cylinder.
Compare the compression readings from all of the cylinders. The lowest reading should not be less than 70 percent of the highest reading. No cylinder reading should be less than 690 kPa (100 psi).
The following are indicators of potential problems: When low compression is caused by the piston rings, compression is low on the first stroke and tends to build up on the following strokes, but does not reach normal. Compression improves considerably with the addition of oil to the cylinder. Use approximately 3 squirts of oil from a plunger-type oiler into the cylinder and replace the gauge and measure again. When low compression is caused by the valves, the measurement is low on the first stroke and does not build up even with the addition of oil. Leaking head gaskets will provide the same results as worn valves but engine coolant may be identified in the crankcase. In addition, a leaking head gasket will give low readings on paired cylinders.
Disconnect GDS2 diagnostic tool or remote start switch.
Install the spark plugs. Refer to «Spark Plug Replacement»(/cadillac/ats/i-2012-2014/remont/testing-diagnostics/#engine-controlsfuel-36l-lfx-repair-instructions) .
Install the ignition coils and spark plugs from all cylinders. Refer to «Ignition Coil Replacement - Bank 1»(/cadillac/ats/i-2012-2014/remont/testing-diagnostics/#engine-controlsfuel-36l-lfx-repair-instructions) , and «Ignition Coil Replacement - Bank 2»(/cadillac/ats/i-2012-2014/remont/testing-diagnostics/#engine-controlsfuel-36l-lfx-repair-instructions) .
Install the intake manifold cover.

Cylinder Leakage Test

Special Tools

EN 35667-A Cylinder Head Leakdown Tester
EN 39313 Spark Plug Port Adapter

For equivalent regional tools, refer to Special Tools .

Disconnect the battery ground negative cable.
Remove the spark plugs. Refer to «Spark Plug Replacement»(/cadillac/ats/i-2012-2014/remont/testing-diagnostics/#engine-controlsfuel-36l-lfx-repair-instructions) .
Rotate the crankshaft to place the piston in the cylinder being tested at top dead center (TDC) of the compression stroke.
Thread the EN 39313 adapter into the spark plug hole.
Install the EN 35667-A tester or equivalent.
Apply shop air pressure to the EN 35667-A tester and adjust according to the manufacturers instructions.
Record the cylinder leakage value. Cylinder leakage that exceeds 25 percent is considered excessive and may require component service. In excessive leakage situations, inspect for the following conditions: Air leakage sounds at the throttle body or air inlet hose that may indicate a worn or burnt intake valve or a broken valve spring Air leakage sounds at the exhaust system tailpipe that may indicate a worn or burnt exhaust valve or a broken valve spring Air leakage sounds from the crankcase, oil level indicator tube, or oil fill tube that may indicate worn piston rings, a damaged piston, a worn or scored cylinder bore, a damaged engine block or a damaged cylinder head Air bubbles in the cooling system may indicate a damaged cylinder head or a damaged cylinder head gasket.
Perform the leakage test on the remaining cylinders and record the values.

Diagnostic Instructions

Perform the «Diagnostic System Check - Vehicle»(/cadillac/ats/i-2012-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
Review «Strategy Based Diagnosis»(/cadillac/ats/i-2012-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
«Diagnostic Procedure Instructions»(/cadillac/ats/i-2012-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Diagnostic Fault Information

Circuit	Short to Ground	Open/High Resistance
Engine Oil Level Sensor Signal	2	1
Engine Oil Level Sensor Ground		1
1. DIC message Engine Oil Level Low always ON 2. DIC message Engine Oil Level Low always OFF

Typical Scan Tool Data

Circuit	Short to Ground	Open	Short to Voltage
Operating Conditions: Ignition ON Parameter Normal Range: OK
Engine Oil Level Sensor/Switch Signal	OK	Low	OK
Engine Oil Level Sensor/Switch Ground		Low

Engine Oil Level Switch

Circuit/System Description

The engine oil level sensor/switch is normally-closed with proper engine oil level. The switch opens when the engine oil level drops below a calibrated level. The engine control module (ECM) monitors the engine oil level signal circuit when the ignition is ON, and the engine is OFF. With the switch in the closed position, the ECM detects a low voltage on the signal circuit. With the switch in the open position, the ECM detects a high voltage on the signal circuit. When high voltage is detected on the signal circuit, the ECM will send a serial data message to the instrument panel cluster (IPC). The IPC will then display a message on the driver information center (DIC) or illuminate a low engine oil level lamp.

The following information determines the message sent from the ECM to the IPC

The Low Engine Oil Level message lamp is displayed only after the ECM detects a high voltage on the signal circuit for three consecutive ignition cycles, followed by an ignition OFF event from 15 minutes to greater than 50 minutes, depending on engine oil temperatures.
The Low Engine Oil Level message is turned OFF when the ECM detects a low voltage on the signal circuit after an ignition OFF event for greater than 90 seconds, followed by an ignition ON event for less than 1 second.

Reference Information

Schematic Reference

«Engine Mechanical Schematics»(/cadillac/ats/i-2012-2014/remont/mechanical/#engine-mechanical-36l-lfx-schematic-wiring-diagrams)
«Instrument Cluster Schematics»(/cadillac/ats/i-2012-2014/remont/gauges-instrument-panels/#instrument-panel-system-displays-and-gauges)

Connector End View Reference

Component Connector End Views

Description and Operation

«Instrument Cluster Description and Operation»(/cadillac/ats/i-2012-2014/remont/gauges-instrument-panels/#instrument-panel-system-displays-and-gauges)
«Indicator/Warning Message Description and Operation»(/cadillac/ats/i-2012-2014/remont/gauges-instrument-panels/#instrument-panel-system-displays-and-gauges)

Electrical Information Reference

«Circuit Testing»(/cadillac/ats/i-2012-2014/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
«Connector Repairs»(/cadillac/ats/i-2012-2014/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
«Testing for Intermittent Conditions and Poor Connections»(/cadillac/ats/i-2012-2014/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
«Wiring Repairs»(/cadillac/ats/i-2012-2014/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information.

Circuit/System Verification

Verify proper engine oil level. If not at proper level Add oil as necessary. If at proper level
Ignition ON, verify the scan tool Engine Oil Level parameter reads OK. If not OK Refer to Circuit/System Testing. If OK
All OK.

Circuit/System Testing

Note. Verify proper engine oil level before continuing with diagnosis.

Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the B35 Engine Oil Level Switch. It may take up to 2 minutes for all vehicle systems to power down.
Test for less than 5 ohms between the ground circuit terminal 1 and ground. If 5 ohms or greater Ignition OFF, disconnect the harness connector at the K20 Engine Control Module. Test for less than 2 ohms in the ground circuit end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms, repair the open/high resistance in the ground connection. If less than 5 ohms
Ignition ON.
Verify the scan tool Engine Oil Level Switch parameter reads Low. If the Engine Oil Level Switch parameter reads OK Ignition OFF, disconnect the harness connector at the K20 Engine Control Module. Test for infinite resistance between the signal circuit terminal 2 and ground. If less than infinite resistance, repair the short to ground on the circuit. If infinite resistance, replace the K20 Engine Control Module. If the Engine Oil Level Switch parameter reads Low
Install a 3A fused jumper wire between the signal circuit terminal 2 and the ground circuit terminal 1.
Verify the scan tool Engine Oil Level Switch parameter reads OK. If the Engine Oil Level Switch parameter reads Low Ignition OFF, disconnect the harness connector at the K20 Engine Control Module, ignition ON. Test for less than 1 V between the signal circuit and ground. If 1 V or greater, repair the short to voltage on the circuit. If less than 1 V Test for less than 2 ohms in the signal circuit end to end. If 2 ohms or greater, repair the open/high resistance on the circuit. If less than 2 ohms, replace the K20 Engine Control Module. If the Engine Oil Level Switch parameter reads OK
Test or replace the B35 Engine Oil Level Switch.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

«Engine Oil Level Sensor and/or Switch Replacement»(/cadillac/ats/i-2012-2014/remont/mechanical/#engine-mechanical-36l-lfx-repair-instructions-on-vehicle)
«Control Module References»(/cadillac/ats/i-2012-2014/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for the ECM replacement, programming, and setup

Oil Consumption Diagnosis

Checks	Causes
DEFINITION: Excessive oil consumption (not due to leaks) is the use of 0.946 L (1 qt) or more of engine oil within 3 200 km (2,000 mi). The causes of excessive oil consumption may include the following conditions
Preliminary	External oil leaks - Refer to Oil Leak Diagnosis . Incorrect oil level or improper reading of the oil level indicator With the vehicle on a level surface, run the engine for a few minutes, allow adequate drain down time (2-3 minutes) and check for the correct engine oil level. Improper oil viscosity Refer to the vehicle owners manual and use the recommended SAE grade and viscosity for the prevailing temperatures. Continuous high speed driving and/or severe usage Crankcase ventilation system restrictions or malfunctioning components Worn valve guides and/or valve stems Worn, missing or improperly installed valve stem oil seals Piston rings broken, worn, not seated properly Allow adequate time for the rings to seat. Replace worn piston rings as necessary. Piston and rings improperly installed or miss-fitted to the cylinder bore

Checks

Causes

DEFINITION: Excessive oil consumption (not due to leaks) is the use of 0.946 L (1 qt) or more of engine oil within 3 200 km (2,000 mi). The causes of excessive oil consumption may include the following conditions

Preliminary

External oil leaks - Refer to Oil Leak Diagnosis . Incorrect oil level or improper reading of the oil level indicator With the vehicle on a level surface, run the engine for a few minutes, allow adequate drain down time (2-3 minutes) and check for the correct engine oil level. Improper oil viscosity Refer to the vehicle owners manual and use the recommended SAE grade and viscosity for the prevailing temperatures. Continuous high speed driving and/or severe usage Crankcase ventilation system restrictions or malfunctioning components Worn valve guides and/or valve stems Worn, missing or improperly installed valve stem oil seals Piston rings broken, worn, not seated properly Allow adequate time for the rings to seat. Replace worn piston rings as necessary. Piston and rings improperly installed or miss-fitted to the cylinder bore

Oil Consumption Diagnosis

Oil Pressure Diagnosis and Testing

Tools Required

J 21867 Pressure Gauge
J-21867-6 Oil Pressure Adapter Fitting

With the vehicle on a level surface, run the vehicle for a few minutes, allow adequate drain down time, 2-3 minutes, and measure for a low oil level.
If required, add the recommended grade engine oil and fill the crankcase until the oil level measures full on the oil level indicator.
Run the engine briefly, 10-15 seconds, and verify low or no oil pressure on the vehicle gauge or light.
Listen for a noisy valve train or a knocking noise.
Inspect for the following: Foamy oil Slow idle speed Plugged oil filter Oil diluted by the following: Water Engine coolant Unburned fuel mixtures Malfunctioning oil filter bypass valve Incorrect or faulty oil pressure gauge Incorrect or faulty oil pressure gauge sensor Improper engine oil viscosity for the expected temperature
Disconnect the oil pressure sensor wiring harness.
Remove the oil pressure sensor.
Install the J 21867 Pressure Gauge with the J-21867-6 Oil Pressure Adapter Fitting.
Measure the engine oil pressure.
Compare the readings to the «Engine Mechanical Specifications (LFX)»(/cadillac/ats/i-2012-2014/remont/mechanical/#engine-mechanical-36l-lfx-specifications__engine-mechanical-specifications-lfx) .
If the engine oil pressure is below specifications, inspect the engine for one or more of the following: Loose oil filter adapter bolts Missing or damaged oil filter adapter O-ring seal or seals Worn or dirty oil pump Loose oil pump-to-engine block bolts Loose, plugged or damaged oil pump screen Missing or damaged oil pump screen O-ring seal Damage or leak in the oil pump screen suction tube Malfunctioning oil pump pressure regulator valve Missing or incorrectly installed oil gallery plugs Loose camshaft intermediate drive shaft bolts Excessive bearing clearance for the following: Connecting rod or rods Crankshaft Camshaft or camshafts Camshaft intermediate drive shaft sprocket Cracked, porous or restricted oil galleries Broken valve lifters
Repair or replace components as necessary.

Oil Leak Diagnosis

Checks	Action
CAUTION: It is important to correctly identify the source of an oil leak. A power steering fluid leak or spillage can travel across the valley area of the engine and run out the weep hole, which is located at the back of the block. Failure to correctly identify the source of an oil leak can lead to the incorrect or unnecessary replacement of components. You can repair most fluid leaks by first visually locating the leak, repairing or replacing the component, or by resealing the gasket surface. Once the leak is identified, determine the cause of the leak. Repair the cause of the leak as well as the leak itself.
Locating and identifying the leak	To determine if the leaking fluid is engine oil, transmission fluid, power steering fluid, brake fluid, or some other fluid, use the visual inspection method.
Visual Inspection Method	Bring the vehicle to normal operating temperature. Park the vehicle over a large sheet of paper, or other clean surface. Wait several minutes, then check for drippings. Identify the type of fluid, and the approximate location of the leak. Visually inspect the suspected area. Use a small mirror to assist in looking at hard to see areas. Check for leaks at sealing surfaces, fittings, or from cracked or damaged components. If you cannot locate the leak, do the following: Completely clean the entire engine and surrounding components. Operate the vehicle for several miles at normal operation temperature and at varying speeds. Park the vehicle over a large sheet of paper, or other clean surface. Wait several minutes, then check for drippings. Identify the type of fluid, and the approximate location of the leak. Visually inspect the suspected area. Use a small mirror to assist in looking at hard to see areas. See possible causes for leaks. If you still cannot locate the leak, use the powder method or the black light and dye method.
Powder Method	Completely clean the entire engine and surrounding components. Apply an aerosol-type powder (baby powder, foot powder, etc.) to the suspected area. Operate the vehicle for several miles at normal operation temperature and at varying speeds. Identify the type of fluid, and the approximate location of the leak, from the discolorations in the powder surface. Visually inspect the suspected area. Use a small mirror to assist in looking at hard to see areas. See possible causes for leaks.
Black Light and Dye Method	A dye and light kit is available for finding leaks. Use the GE 28428-E High-Intensity Black Light Kit or equivalent. Refer to the manufacturer's instructions when using the tool. Visually inspect the suspected area. Use a small mirror to assist in looking at hard to see areas. See possible causes for leaks.
Possible Causes for Leaks	Check for the following conditions: Higher than recommended fluid levels Higher than recommended fluid pressures Plugged or malfunctioning fluid filters or pressure bypass valves Plugged or malfunctioning engine ventilation system Improperly tightened or damaged fasteners Cracked or porous components Improper sealants or gaskets where required Improper sealant or gasket installation Damaged or worn gaskets or seals Damaged or worn sealing surfaces

CAUTION
It is important to correctly identify the source of an oil leak. A power steering fluid leak or spillage can travel across the valley area of the engine and run out the weep hole, which is located at the back of the block. Failure to correctly identify the source of an oil leak can lead to the incorrect or unnecessary replacement of components.

Oil Leak Diagnosis

Crankcase Ventilation (CV) System Inspection

Test for vacuum at the vacuum hose where it connects to the crankcase ventilation housing. There should be manifold vacuum present at the hose. If there is no vacuum, inspect for a plugged hose, leaking hose or a plugged vent adapter.
Plug the end of the vacuum hose while the engine is running. Inspect the hose for any areas that collapse when the end of the hose is blocked. Replace the hose if it collapses when blocked.
If oil has accumulated in the intake air duct, inspect for the following conditions: Plugged vacuum orifice in the crankcase ventilation housing Plugged or restricted crankcase ventilation housing Excessive crankcase pressure or blow-by, refer to «Oil Consumption Diagnosis»(/cadillac/ats/i-2012-2014/remont/mechanical/#engine-mechanical-36l-lfx-diagnostic-information-and-procedures__oil-consumption-diagnosis) .
Additional items to inspect: Plugged or leaking fresh air vent hose assembly or vent adapter Plugged or restricted passages in the throttle body Missing or damaged O-ring seals on the vent adapter Inspect the cam covers, the oil pan gasket, and other sealing areas for leaks

Results of Incorrect Operation

A plugged crankcase ventilation housing or hose may contribute to the following conditions

A rough idle
Stalling or a slow idle speed
Oil leaks
Oil accumulation in the intake air duct
Sludge in the engine

A leaking housing or hose may contribute to the following conditions

A rough idle
Stalling
Unstable idle speed

Diagnostic Aids

A chirping or squeal noise may be intermittent due to moisture on the drive belts or the pulleys. It may be necessary to spray a small amount of water on the drive belts in order to duplicate the customers concern. If spraying water on the drive belt duplicates the symptom, cleaning the belt pulleys may be the probable solution.
If the noise is intermittent, verify the accessory drive components by varying their loads making sure they are operated to their maximum capacity. An overcharged A/C system, power steering system with a pinched hose or wrong fluid, or a generator failing are suggested items to inspect.
A chirping, squeal or whine noise may be caused by a loose or improper installation of a body or suspension component. Other items of the vehicle may also cause the noise.
The drive belts will not cause a whine noise.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

2 The noise may not be engine related. This step is to verify that the engine is making the noise. If the engine is not making the noise do not proceed further with this table.
3 The noise may be an internal engine noise. Removing the drive belts one at a time and operating the engine for a brief period will verify the noise is related to the drive belt. When removing the drive belt the water pump may not be operating and the engine may overheat. Also DTCs may set when the engine is operating with the drive belts removed.
4 Inspect all drive belt pulleys for pilling. Pilling is the small balls or pills or it can be strings in the drive belt grooves from the accumulation of rubber dust.
6 Misalignment of the pulleys may be caused from improper mounting of the accessory drive component, incorrect installation of the accessory drive component pulley, or the pulley bent inward or outward from a previous repair. Test for a misaligned pulley using a straight edge in the pulley grooves across two or three pulleys. If a misaligned pulley is found refer to that accessory drive component for the proper installation procedure for that pulley.
10 Inspecting of the fasteners can eliminate the possibility that a wrong bolt, nut, spacer, or washer was installed.
12 Inspecting the pulleys for being bent should include inspecting for a dent or other damage to the pulleys that would prevent the drive belt from not seating properly in all of the pulley grooves or on the smooth surface of a pulley when the back side of the belt is used to drive the pulley.
14 This test is to verify that the drive belt tensioner operates properly. If the drive belt tensioner is not operating properly, proper belt tension may not be achieved to keep the drive belt from slipping which could cause a squeal noise.
15 This test is to verify that the drive belt is not too long, which would prevent the drive belt tensioner from working properly. Also if an incorrect length drive belt was installed, it may not be routed properly and may be turning an accessory drive component in the wrong direction.
16 Misalignment of the pulleys may be caused from improper mounting of the accessory drive component, incorrect installation of the accessory drive component pulley, or the pulley bent inward or outward from a previous repair. Test for a misaligned pulley using a straight edge in the pulley grooves across two or three pulleys. If a misaligned pulley is found refer to that accessory drive component for the proper installation procedure for that pulley.
17 This test is to verify that the pulleys are the correct diameter or width. Using a known good vehicle compare the pulley sizes.
19 Replacing the drive belt when it is not damaged or there is not excessive pilling will only be a temporary repair.

Step	Action	Yes	No
CAUTION: Refer to Belt Dressing Caution . DEFINITION: The following items are indications of chirping: A high pitched noise that is heard once per revolution of the drive belt or a pulley. Chirping may occur on cold damp start-ups and will subside once the vehicle reaches normal operating temp. DEFINITION: The following items are indications of drive belt squeal: A loud screeching noise that is caused by a slipping drive belt. This is unusual for a drive belt with multiple ribs. The noise occurs when a heavy load is applied to the drive belt, such as an air conditioning compressor engagement snapping the throttle, or slipping on a seized pulley or a faulty accessory drive component. DEFINITION: The following items are indications of drive belt whine: A high pitched continuous noise. The noise may be caused by an accessory drive component failed bearing.
1	Did you review the Drive Belt Symptom operation and perform the necessary inspections?	Go to Step 2	Go to Symptoms - Engine Mechanical
2	Verify that there is a chirping, squeal or whine noise. Does the engine make the chirping squeal or whine noise?	Go to Step 3	Go to Diagnostic Aids
3	Remove the drive belt. If the engine has multiple drive belts, remove the belts one at a time and perform the test below each time a belt is removed. Operate the engine for no longer than 30-40 seconds. Repeat this test if necessary by removing the remaining belt(s). Does the chirping, squeal or whine noise still exist?	Go to Symptoms - Engine Mechanical	Go to Step 4
4	If diagnosing a chirping noise, inspect for severe pilling exceeding 1/3 of the belt groove depth. If diagnosing a squeal or whine noise, proceed to step 13. Do the belt grooves have pilling?	Go to Step 5	Go to Step 6
5	Clean the drive belt pulleys with a suitable wire brush. Did you complete the repair?	Go to Step 20	Go to Step 6
6	Inspect for misalignment of the pulleys. Are any of the pulleys misaligned?	Go to Step 7	Go to Step 8
7	Replace or repair any misaligned pulleys. Did you complete the repair?	Go to Step 20	Go to Step 8
8	Inspect for bent or cracked brackets. Did you find any bent or cracked brackets?	Go to Step 9	Go to Step 10
9	Replace any bent or cracked brackets. Did you complete the repair?	Go to Step 20	Go to Step 10
10	Inspect for improper, loose or missing fasteners. Did you find the condition?	Go to Step 11	Go to Step 12
11	CAUTION: Refer to Fastener Caution . Tighten any loose fasteners. Refer to Fastener Tightening Specifications . Replace any improper or missing fasteners. Did you complete the repair?	Go to Step 20	Go to Step 12
12	Inspect for a bent pulley. Did you find the condition?	Go to Step 18	Go to Step 19
13	Inspect for an accessory drive component seized bearing or a faulty accessory drive component. Did you find and correct the condition?	Go to Step 20	Go to Step 14
14	If diagnosing a whine noise and the condition still exist, proceed to Diagnostic Aids. Test the drive belt tensioner for proper operation. Refer to Drive Belt Tensioner Diagnosis . Did you find and correct the condition?	Go to Step 20	Go to Step 15
15	Inspect for the correct drive belt length. Did you find and correct the condition?	Go to Step 20	Go to Step 16
16	Inspect for misalignment of a pulley. Did you find and correct the condition?	Go to Step 20	Go to Step 17
17	Inspect for the correct pulley size. Did you find and correct the condition?	Go to Step 20	Go to Diagnostic Aids
18	Replace the bent pulley. Did you complete the repair?	Go to Step 20	Go to Step 19
19	Replace the drive belt. Refer to Drive Belt Replacement . Did you complete the repair?	Go to Step 20	Go to Diagnostic Aids
20	Operate the system in order to verify the repair. Did you correct the condition?	System OK	Go to Step 3

CAUTION
Refer to Belt Dressing Caution .

CAUTION
Refer to Fastener Caution .

Drive Belt Chirping, Squeal, and Whine Diagnosis

The accessory drive components can have an affect on engine vibration. Vibration from the engine operating may cause a body component or another part of the vehicle to make rumbling noise. Vibration can be caused by, but not limited to the A/C system over charged, the power steering system restricted or the incorrect fluid, or an extra load on the generator. To help identify an intermittent or an improper condition, vary the loads on the accessory drive components.

The drive belt may have a rumbling condition that can not be seen or felt. Sometimes replacing the drive belt may be the only repair for the symptom.

If replacing the drive belt, completing the diagnostic table, and the noise is only heard when the drive belts are installed, there might be an accessory drive component with a failure. Varying the load on the different accessory drive components may aid in identifying which component is causing the rumbling noise.

The numbers below refer to the step numbers on the diagnostic table.

2 This test is to verify that the symptom is present during diagnosing. Other vehicle components may cause a similar symptom.
3 This test is to verify that one of the drive belts is causing the rumbling noise or vibration. Rumbling noise may be confused with an internal engine noise due to the similarity in the description. Remove only one drive belt at a time if the vehicle has multiple drive belts. When removing the drive belts the water pump may not be operating and the engine may overheat. Also DTCs may set when the engine is operating with the drive belts removed.
4 Inspecting the drive belts is to ensure that they are not causing the noise. Small cracks across the ribs of the drive belt will not cause the noise. Belt separation is identified by the plys of the belt separating and may be seen at the edge of the belt our felt as a lump in the belt.
5 Small amounts of pilling is normal condition and acceptable. When the pilling is severe the drive belt does not have a smooth surface for proper operation.
9 Inspecting of the fasteners can eliminate the possibility that the wrong bolt, nut, spacer, or washer was installed.
11 This step should only be performed if the water pump is driven by the drive belt. Inspect the water pump shaft for being bent. Also inspect the water pump bearings for smooth operation and excessive play. Compare the water pump with a known good water pump.
12 Accessory drive component brackets that are bent, cracked, or loose may put extra strain on that accessory component causing it to vibrate.

Step	Action	Yes	No
CAUTION: Refer to Belt Dressing Caution . DEFINITION: The following items are indications of drive belt rumbling: A low pitch tapping, knocking, or thumping noise heard at or just above idle. Heard once per revolution of the drive belt or a pulley. Rumbling may be caused from: Pilling, the accumulation of rubber dust that forms small balls (pills) or strings in the drive belt pulley groove The separation of the drive belt A damaged drive belt DEFINITION: The following items are indications of drive belt vibration: The vibration is engine-speed related. The vibration may be sensitive to accessory load.
1	Did you review the Drive Belt Symptom operation and perform the necessary inspections?	Go to Step 2	Go to Symptoms - Engine Mechanical
2	Verify that there is a rumbling noise or that the vibration is engine related. Does the engine make the rumbling noise or vibration?	Go to Step 3	Go to Diagnostic Aids
3	Remove the drive belt. If the engine has multiple drive belts, remove the belts one at a time and perform the test below each time a belt is removed. Operate the engine for no longer than 30-40 seconds. Repeat this test if necessary by removing the remaining belt(s). Does the rumbling or vibration still exist?	Go to Symptoms - Engine Mechanical or Go to Vibration Analysis - Engine	Go to Step 4
4	Inspect the drive belts for wear, damage, separation, sections of missing ribs, and debris build-up. Did you find any of these conditions?	Go to Step 7	Go to Step 5
5	Inspect for severe pilling of more than 1/3 of the drive belt pulley grooves. Did you find severe pilling?	Go to Step 6	Go to Step 7
6	Clean the drive belt pulleys using a suitable wire brush. Reinstall the drive belts. Refer to Drive Belt Replacement . Did you correct the condition?	Go to Step 8	Go to Step 7
7	Install a new drive belt. Refer to Drive Belt Replacement . Did you complete the replacement?	Go to Step 8	Go to Step 9
8	Operate the system in order to verify the repair. Did you correct the condition?	System OK	Go to Step 9
9	Inspect for improper, loose or missing fasteners. Did you find any of these conditions?	Go to Step 10	Go to Step 11
10	Tighten any loose fasteners. Refer to Fastener Tightening Specifications . Replace improper or missing fasteners. Did you complete the repair?	Go to Step 13	Go to Step 11
11	Inspect for a bent water pump shaft. Refer to Water Pump Replacement (LFX) . Did you find and correct the condition?	Go to Step 13	Go to Step 12
12	Inspect for bent or cracked brackets. Did you find and correct the condition?	Go to Step 13	Go to Diagnostic Aids
13	Operate the system in order to verify the repair. Did you correct the condition?	System OK	Go to Step 3

CAUTION
Refer to Belt Dressing Caution .

Drive Belt Rumbling and Vibration Diagnosis

If the drive belt repeatedly falls off the drive belt pulleys, this is because of pulley misalignment.

An extra load that is quickly applied on released by an accessory drive component may cause the drive belt to fall off the pulleys. Verify the accessory drive components operate properly.

If the drive belt is the incorrect length, the drive belt tensioner may not keep the proper tension on the drive belt.

Excessive wear on a drive belt is usually caused by an incorrect installation or the wrong drive belt for the application.

Minor misalignment of the drive belt pulleys will not cause excessive wear, but will probably cause the drive belt to make a noise or to fall off.

Excessive misalignment of the drive belt pulleys will cause excessive wear but may also make the drive belt fall off.

The numbers below refer to the step numbers on the diagnostic table.

2 This inspection is to verify the condition of the drive belt. Damage may of occurred to the drive belt when the drive belt fell off. The drive belt may of been damaged, which caused the drive belt to fall off. Inspect the belt for cuts, tears, sections of ribs missing, or damaged belt plys.
4 Misalignment of the pulleys may be caused from improper mounting of the accessory drive component, incorrect installation of the accessory drive component pulley, or the pulley bent inward or outward from a previous repair. Test for a misaligned pulley using a straight edge in the pulley grooves across two or three pulleys. If a misaligned pulley is found refer to that accessory drive component for the proper installation procedure of that pulley.
5 Inspecting the pulleys for being bent should include inspecting for a dent or other damage to the pulleys that would prevent the drive belt from not seating properly in all of the pulley grooves or on the smooth surface of a pulley when the back side of the belt is used to drive the pulley.
6 Accessory drive component brackets that are bent or cracked will let the drive belt fall off.
7 Inspecting of the fasteners can eliminate the possibility that a wrong bolt, nut , spacer, or washer was installed. Missing. loose, or the wrong fasteners may cause pulley misalignment from the bracket moving under load. Over tightening of the fasteners may cause misalignment of the accessory component bracket.
13 The inspection is to verify the drive belt is correctly installed on all of the drive belt pulleys. Wear on the drive belt may be caused by mis-positioning the drive belt by one groove on a pulley.
14 The installation of a drive belt that is two wide or two narrow will cause wear on the drive belt. The drive belt ribs should match all of the grooves on all of the pulleys.
15 This inspection is to verify the drive belt is not contacting any parts of the engine or body while the engine is operating. There should be sufficient clearance when the drive belt accessory drive components load varies. The drive belt should not come in contact with an engine or a body component when snapping the throttle.

Step	Action	Yes	No
CAUTION: Refer to Belt Dressing Caution . DEFINITION: The drive belt falls off the pulleys or may not ride correctly on the pulleys.DEFINITION: Wear at the outside ribs of the drive belt due to an incorrectly installed drive belt.
1	Did you review the Drive Belt Symptom operation and perform the necessary inspections?	Go to Step 2	Go to Symptoms - Engine Mechanical
2	If diagnosing excessive wear, proceed to step 13. If diagnosing a drive belt that falls off, inspect for a damaged drive belt. Did you find the condition?	Go to Step 3	Go to Step 4
3	Install a new drive belt. Refer to Drive Belt Replacement . Does the drive belt continue to fall off?	Go to Step 4	System OK
4	Inspect for misalignment of the pulleys. Did you find and repair the condition?	Go to Step 12	Go to Step 5
5	Inspect for a bent or dented pulley. Did you find and repair the condition?	Go to Step 12	Go to Step 6
6	Inspect for a bent or a cracked bracket. Did you find and repair the condition?	Go to Step 12	Go to Step 7
7	Inspect for improper, loose or missing fasteners. Did you find loose or missing fasteners?	Go to Step 8	Go to Step 9
8	CAUTION: Refer to Fastener Caution . Tighten any loose fasteners. Refer to Fastener Tightening Specifications . Replace improper or missing fasteners. Does the drive belt continue to fall off?	Go to Step 9	System OK
9	Test the drive belt tensioner for operating correctly. Refer to Drive Belt Tensioner Diagnosis . Does the drive belt tensioner operate correctly?	Go to Step 11	Go to Step 10
10	Replace the drive belt tensioner. Refer to Drive Belt Tensioner Replacement . Does the drive belt continue to fall off?	Go to Step 11	System OK
11	Inspect for failed drive belt idler and drive belt tensioner pulley bearings. Did you find and repair the condition?	Go to Step 12	Go to Diagnostic Aids
12	Operate the system in order to verify the repair. Did you correct the condition?	System OK	Go to Step 2
13	Inspect the drive belt for the proper installation. Refer to Drive Belt Replacement . Did you find this condition?	Go to Step 16	Go to Step 14
14	Inspect for the proper drive belt. Did you find this condition?	Go to Step 16	Go to Step 15
15	Inspect for the drive belt rubbing against a bracket, hose, or wiring harness. Did you find and repair the condition?	Go to Step 17	Go to Diagnostic Aids
16	Replace the drive belt. Refer to Drive Belt Replacement . Did you complete the replacement?	Go to Step 17
17	Operate the system in order to verify the repair. Did you correct the condition?	System OK

CAUTION
Refer to Belt Dressing Caution .

CAUTION
Refer to Fastener Caution .

Drive Belt Falls Off and Excessive Wear Diagnosis

Drive Belt Tensioner Diagnosis

Step	Action	Yes	No
1	Remove the drive belt and inspect the drive belt tensioner pulley. Is the drive belt tensioner pulley loose or misaligned?	Go to Step 4	Go to Step 2
2	Rotate the drive belt tensioner. Does the tensioner rotate without any unusual resistance or binding?	Go to Step 3	Go to Step 4
3	Use a torque wrench in order to measure the torque required to move the tensioner off of the stop. Use a torque wrench on a known good tensioner in order to measure the torque required to move the tensioner off of the stop. Is the first torque reading within 10 percent of the second torque reading?	System OK	Go to Step 4
4	Replace the drive belt tensioner. Is the repair complete?	System OK

Drive Belt Tensioner Diagnosis

Engine Mechanical - 3.6l (Lfx) - Diagnostic Information and Procedures Cadillac ATS I

Strategy Based Diagnostics

Visual/Physical Inspection

Intermittent

Symptom List

Base Engine Misfire without Internal Engine Noises

Base Engine Misfire with Abnormal Internal Lower Engine Noises

Base Engine Misfire with Abnormal Valve Train Noise

Base Engine Misfire with Coolant Consumption

Base Engine Misfire with Excessive Oil Consumption

Engine Noise on Start-Up, but Only Lasting a Few Seconds

Upper Engine Noise, Regardless of Engine Speed

Lower Engine Noise, Regardless of Engine Speed

Engine Noise Under Load

Engine Will Not Crank - Crankshaft Will Not Rotate

Coolant in Combustion Chamber

Coolant in Engine Oil

Engine Compression Test

Cylinder Leakage Test

Diagnostic Instructions

Diagnostic Fault Information

Typical Scan Tool Data

Circuit/System Description

Reference Information

Circuit/System Verification

Circuit/System Testing

Repair Instructions

Oil Consumption Diagnosis

Oil Pressure Diagnosis and Testing

Oil Leak Diagnosis

Crankcase Ventilation (CV) System Inspection

Results of Incorrect Operation

Diagnostic Aids

Test Description

Drive Belt Tensioner Diagnosis

More articles — Engine

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