Inspection and Verification
Since diagnosis and testing actually begins when repairs are taken on, the following procedure is recommended.
- Verify the customer concern by operating the system.
- Visually inspect for obvious signs of mechanical damage or electrical damage. If the concern cannot be reproduced, carry out a road test and/or visual check with the aid of the following table. Visual Inspection Chart Mechanical Coolant leaks Oil leaks Leaks in the fuel system Visibly damaged or worn parts Loose or missing nuts or bolts
- If an obvious cause for an observed or reported concern is found, correct the cause (if possible) before proceeding to the next step.
- If the concern is not visually evident, verify the symptom and refer to «Symptom Chart»(ref-311296-S06927120102009032500000) .
Symptom Chart
| Condition | Possible Source | Action |
|---|---|---|
| Difficult to start during hot or cold start | Piston ring(s) worn, damaged, sticking or worn piston/cylinder. | INSTALL a new engine. |
| Head gasket damaged. | INSPECT the head gasket. | |
| Fuel system damaged or inoperative. | Refer to Fuel Charging and Controls article. | |
| Ignition system inoperative. | Refer to Engine Ignition article. | |
| Poor Idling | Restricted exhaust system. | INSPECT the exhaust system. Refer to Exhaust System article. |
| Vacuum leak. | CARRY out the Intake Manifold Vacuum Test . REPAIR and INSTALL new components as necessary. | |
| Burned valve(s). | INSPECT the valve(s). | |
| Incorrect valve to valve seat contact. | INSPECT the valve and valve seat. | |
| Head gasket damaged. | INSPECT the head gasket. | |
| Fuel system damaged or inoperative. | Refer to Fuel Charging and Controls article. | |
| Insufficient power | Compression leakage from valve seat. | INSPECT the valve or valve seat. |
| Valve sticking. | INSPECT valve stem to valve guide clearance or carbon accumulation. | |
| Valve spring weak or broken. | INSPECT the valve spring. | |
| Head gasket damaged. | INSPECT the head gasket. | |
| Cylinder head cracked or distorted. | INSPECT the cylinder head. | |
| Piston ring(s) worn, damaged or sticking. | INSTALL a new engine. | |
| Fuel system damaged or inoperative. | Refer to Fuel Charging and Controls article. | |
| Brakes dragging. | Refer to Brake System - General Information article. | |
| Restricted exhaust system. | INSPECT the exhaust system. Refer to Exhaust System article. | |
| Excessive or insufficient compression. | Valve(s) burnt or sticking. | INSPECT the valve(s). |
| Valve spring(s) weak or broken. | INSPECT the valve spring(s). | |
| Piston ring(s) worn, damaged, sticking or worn piston/cylinder. | INSTALL a new engine. | |
| Head gasket damaged. | INSPECT the head gasket. | |
| Carbon accumulation in combustion chamber. | ELIMINATE carbon build up. | |
| Fuel system damaged or inoperative. | Refer to Fuel Charging and Controls article. | |
| Excessive oil consumption | Piston ring(s) worn, damaged, sticking or worn piston/cylinder. | INSTALL a new engine. |
| Valve stem seal worn or missing. | INSPECT the valve or valve stem seal. | |
| Oil leakage. | REPAIR oil leakage. | |
| Valve stem or valve guide worn. | INSPECT the valve stem or valve guide. | |
| Incorrect oil viscosity. | DRAIN and FILL with new oil. | |
| Diluted oil. | CHECK oil dilution. DRAIN and FILL as necessary. | |
| Crankcase overfilled. | CHECK and adjust the oil level. | |
| Incorrect oil pressure. | CHECK the oil pressure. REPAIR as necessary. | |
| Engine noise | Excessive crankshaft main bearing clearance. | INSTALL a new engine. |
| Excessive crankshaft end play. | INSTALL a new engine. | |
| Excessive connecting rod bearing oil clearance. | INSTALL a new engine. | |
| Piston/cylinder worn. | INSTALL a new engine. | |
| Piston ring damaged. | INSTALL a new engine. | |
| Connecting rod bent. | INSTALL a new engine. | |
| Valve spring(s) broken. | INSPECT the valve spring(s). | |
| Excessive valve guide clearance. | INSPECT the valve guide or valve. | |
| Cooling system inoperative (water pump, vibration of radiator) | Refer to Refer to Engine Cooling or Supercharger Cooling article. | |
| Fuel system inoperative. | Refer to Fuel Charging and Controls article. | |
| Excessive carbon buildup. | ELIMINATE carbon buildup. | |
| Exhaust gas leakage. | REPAIR leakage. Refer to Exhaust System article. | |
| Incorrect drive belt tension. | INSPECT the drive belt tension. Refer to Accessory Drive article. | |
| Generator front bearing worn. | Refer to Generator and Regulator article. | |
| Tappet noise, engine running | Incorrect tappet clearance. | CHECK and ADJUST the tappet clearance as necessary. |
Symptom Chart
Oil Consumption Test
The following diagnostic procedure is used to determine the source of excessive oil consumption.
Note. Oil use is normally greater during the first 16,100 km (10,000 miles) of service. As mileage increases, oil use decreases. Vehicles in normal service should get a least 16,000 km (10,000 miles) per liter. High speed driving, towing, high ambient temperature and other factors may result in greater oil use.
- Define excessive consumption, such as the number of miles driven per liter of oil used. Also determine customers's driving habits, such as sustained high speed operation, towing, extended idle and other considerations.
- Verify that the engine has no external oil leaks as described under Engine Oil Leaks.
- Verify that the engine has the correct oil level.
- Verify that the engine is not being run in an overfilled condition. Check the oil level at least five minutes after a hot shutdown with the vehicle parked on a level surface. In no case should the level be above the top of the cross-hatched area and the letter "F" in FULL. If significantly overfilled, carry out step 5, sub steps 1 through 4.
- Carry out an oil consumption test: Drain engine oil and fill with one liter less than the recommended amount. Run the engine for three minutes (10 minutes if cold), and allow oil to drain back for at least five minutes with vehicle parked on level surface. Remove the oil level indicator and wipe clean. (Do not wipe with anything contaminated with silicone compounds.) Install the oil level indicator making sure to seat the oil level indicator firmly in the oil level indicator tube. Remove the oil level indicator and draw a mark on the back (unmarked) surface at the indicated oil level. (This level should be about the same as the ADD mark on the face of the oil level indicator.) Add one liter of oil. Start the engine and allow to idle for at least two minutes. Shut off the engine and allow the engine oil to drain back for at least five minutes. Mark the oil level dipstick, using the procedure above. (This level may range from slightly below the top of the cross-hatched area to slightly below the letter "F" in FULL. Record the vehicles mileage. Instruct the customer to drive the vehicle as usual and: Check the oil level regularly at intervals of 160-240 km (100-150 miles). Return to the service point when the oil level drops below the lower (ADD) mark on the oil level indicator. Add only full liters of the same oil in an emergency. Note the mileage at which the oil is added. Check the oil level under the same conditions and at the same location as in steps 3 and 4. Measure the distance from the oil level to the UPPER mark on the oil level indicator and record. Measure the distance between the two scribe marks and record. Divide the first measurement by the second. Divide the distance driven during the oil test by the result. This quantity is the approximate oil consumption rate in kilometers per liter or in mile per quart. If the oil consumption rate is unacceptable go to Step 6.
- Check the positive crankcase ventilation (PCV) system. Make sure the system is not plugged.
- Check for plugged oil drain-back holes in the cylinder head and cylinder block.
- If the condition still exists after carrying out the above tests go to step 9.
- Carry out a cylinder compression test. Refer to «Oil Consumption Test»(ref-311296-S06687857182009032500000) procedure : Compression Test. This can help determine the source of oil consumption such as valves, piston rings or other areas.
- Check valve guides for excessive guide clearance. Install new valve stem seals after verifying valve guide clearance.
- Worn or damaged internal engine components can cause excessive oil consumption. Small deposits of oil on the tips of the spark plugs can be a clue to internal oil consumption.
Intake Manifold Vacuum Test
Bring the engine to normal operating temperature. Connect a vacuum gauge or equivalent to the intake manifold. Run the engine at the specified idle speed.
The vacuum gauge should read between 51-74 kPa (15-22 in-Hg) depending upon the engine condition and the altitude at which the test is performed. Subtract 4.0193 kPa (1 in-Hg) from the specified reading for every 304.8 m (1,000 feet) of elevation above sea level.
The reading should be steady. As necessary, adjust the gauge damper control (where used) if the needle is fluttering rapidly. Adjust damper until needle moves easily without excessive flutter.
- Verify the customer concern. Concerns have been separated into Leaks and noise vibration and harshness (NVH) for ease of use.
- Visually inspect for obvious signs of mechanical or electrical damage. If an obvious cause for an observed or reported concern is found, correct the cause (if possible) before proceeding to the next step.
- If the concern is not visually evident, verify the symptom and refer to «Symptom Chart»(ref-311296-S06927120102009032500000) .
| Mechanical |
|---|
| Coolant level Coolant leaks, Refer to Engine Cooling article. Oil level Oil leaks Visibly damaged or worn parts Loose or missing nuts or bolts |
Visual Inspection Chart
Symptom charts
| Symptom | Possible cause | Action |
|---|---|---|
| External coolant leaks | Damaged hose(s) Damaged expansion tank Damaged radiator Leaking seals/gaskets Cracked/damaged casings | For cooling system checks, Refer to Engine Cooling article. |
| Internal coolant leaks Note: This may be indicated by the production of white smoke from the exhaust. | Leaking seals/gaskets Cracked/damaged casings | For cooling system checks, Refer to Engine Cooling article. |
| Engine overheats | Insufficient coolant Insufficient oil Pressure cap fault Thermostat not opening Coolant pump failure Cooling fan failure | For cooling system checks, Refer to Engine Cooling article. |
| Engine takes too long to reach operating temperature | Thermostat stuck open | For cooling system checks, Refer to Engine Cooling article. |
| External oil leaks | Gaskets Seals Hoses Oil filter Oil cooler Damaged/Cracked casings Crankcase ventilation system Piston ring blow-by | Clean and confirm the area of the leak. Check the visual condition of oil carrying components. Check the crankcase ventilation system, Refer to Engine Emission Control article. Carry out a compression test, Refer to Pinpoint Test A . |
| Internal oil leaks (leaks into coolant or combustion chamber) Note: This may be indicated by the production of blue smoke from the exhaust. | Gaskets Seals Hoses Damaged/Cracked casings Worn valve guides Worn cylinder bores/pistons Broken piston rings | Check for traces of oil in the coolant. Check for evidence of oil in the combustion chambers (deposits on the glow plugs, etc). Confirm oil consumption and vehicle usage with the owner/driver. Carry out an oil consumption test, Refer to Pinpoint Test B . |
Symptom chart, leaks
Note. As the checks suggested here are open to interpretation, they should be used as a guide only. Descriptions of noises, etc, are in general terms, so depend on a degree of experience on the part of the technician.
| Symptom | Possible cause | Action |
|---|---|---|
| Rattle/ticking from top of engine | Valve gear noise Camshaft bearing noise Camshaft chain noise Tensioner noise Vacuum pump noise High pressure fuel pump noise | Check the engine oil pressure, Refer to Pinpoint Test C . Check the function of the hydraulic tappets and the camshaft condition, See Camshaft Lobe Lift . . Check the camshaft bearings, and See Camshaft Bearing Journal Clearance . Check the camshaft chains and tensioners, and Refer to Cylinder Head LH article. Check the vacuum pump, and Refer to Brake Vacuum Pump - 2.7L Diesel article. Check the high pressure fuel pump, and Refer to Fuel Injection Pump article. |
| Growl from top of engine | High pressure fuel pump belt noise High pressure fuel pump belt tensioner noise | Check the high pressure fuel pump belt and tensioner, Refer to Fuel Injection Pump Belt article. |
| Squeaking/Creaking/Squeal from front of engine | Accessory drive belt Accessory drive belt tensioner Driven components on accessory drive belt | Check the accessory drive belt and driven components, Refer to Accessory Drive - 2.7L Diesel article. |
| Whine/Slap/Growl from front of engine | Accessory drive belt Accessory drive belt tensioner Driven components on accessory drive belt Timing belt noise Timing belt tensioner noise | Check the accessory drive belt and driven components, Refer to Accessory Drive - 2.7L Diesel article. Check the timing belt and tensioners, and Refer to Timing Belt article. |
| Knock from lower half of engine (often worse with a cold engine) | Piston slap Piston pin noise Connecting rod bearing noise | Check the engine oil pressure, Refer to Pinpoint Test C . Refer to general procedures for more information, See Piston Inspection , Piston Pin Diameter , and Connecting Rod Large End Bore . . |
| Knock/Rumble from lower half of engine (often worse on overrun) | Main bearing noise | Check the engine oil pressure, Refer to Pinpoint Test C . Refer to general procedures for more information, See Crankshaft Main Bearing Journal Clearance . |
| Misfire/Rough running | Engine management Fuel charging and controls Exhaust gas recirculation (EGR) system Burnt/sticking valves Worn valve guides Worn cylinder bores/pistons Broken piston rings Damaged/Cracked casings | For engine management system tests, Refer to Electronic Engine Controls article. For fuel charging and controls systems tests, and Refer to Fuel Charging and Controls article. For EGR system tests, and Refer to Engine Emission Control article. Carry out a compression test, Refer to Pinpoint Test A and Cylinder Head Distortion . . |
Symptom chart, NVH
Pinpoint Test A: CHECK THE CYLINDER COMPRESSIONS
| WARNING | Only compression testers able to read the higher compression pressures found in diesel engines should be used. Failure to follow this instruction may result in personal injury. |
Note. Where possible, compression testing should be carried out on an engine at operating temperature.
Pinpoint Test A
A1
CARRY OUT A DRY CYLINDER COMPRESSION TEST
- Make sure the parking brake is applied and that the selector lever is in neutral (or park for vehicles with automatic transmission).
- Turn the ignition switch to the OFF position.
- Remove the starter relay.
- Disconnect the starter motor solenoid connector.
- Connect a suitable remote starter device to the starter motor solenoid.
- Remove the glow plugs, Refer to «Glow Plugs»(ref-311318-S31983937132009032500000) article.
- Install adaptor 303-1131 in place of the glow plug in the first cylinder to be tested.
- Connect a suitable compression tester to the adaptor. See warning above.
- Using the remote starter device, crank the engine a minimum of five revolutions.
- Record the compression figure and the number of revolutions taken to reach it.
- Repeat steps 7 - 10 above for the remaining cylinders, cranking the engine for a similar number of revolutions each time.
- Compare the compression figures across all the cylinders.
Are the compression figures within 10% of each other?
YES Unless the compression figures are universally very low (experience will indicate this), check for other causes for the customer complaint.
NO Go to step 2 . → 2
A2
CARRY OUT A WET CYLINDER COMPRESSION TEST
- CAUTION: If engine oil is introduced into the cylinders, run the engine at 2,000 RPM for a minimum of ten minutes after completing testing to prevent damage to the catalytic converters. Failure to follow this instruction may result in damage to the vehicle.
- NOTE: There is a combustion chamber in the top of each piston. Make sure that the oil is not allowed to run into this chamber.
- Using a suitable oil can with a flexible spout, introduce a small amount of clean engine oil into the cylinder just before testing, such that the oil is able to run between the piston and the cylinder bore.
- Repeat steps 7 - 10 from the test above, introducing oil into each cylinder just before testing.
- Compare the compression figures across all the cylinders.
Is the compression figure higher than the dry test?
YES A higher figure following the introduction of oil may indicate a worn or damaged cylinder bore, piston and/or piston rings. Disassembly would be required to confirm this.
NO Clear any DTCs which may have been induced by the test.
Pinpoint Test B: OIL CONSUMPTION TEST
Note. Oil consumption will vary, depending on a number of factors. New engines will normally use more oil than 'run-in' engines, although a guideline would be to expect 16,000 Km (10,000 mls) per liter.
Pinpoint Test B
B1
CHECK FOR EXCESSIVE OIL CONSUMPTION
- Start the engine and allow it to run until it reaches operating temperature.
- Make sure the vehicle is parked on a level surface and switch off.
- Allow to settle for at least five minutes.
- Check the oil level.
- Correct the level, if necessary, and record the reading and mileage in the vehicle history.
- Make sure that the owner/driver is aware that a test is being carried out, and that they should not top-up their oil level for the duration of the test, but should check the level every 160-240 Km (100-150 miles).
- When the oil level reaches the ADD mark, the customer should bring the vehicle in to be checked.
- Top-up the oil to the level at the beginning of the test and record the amount of oil needed to do so, and the mileage covered in the course of the test.
- From this, the consumption can be calculated, and a decision made as to whether or not the consumption is considered excessive.
Is the consumption excessive for the mileage and/or use?
YES Disassembly will be required to check the components indicated in the symptom chart.
NO No further action is necessary.
Pinpoint Test C: CHECK THE ENGINE OIL PRESSURE
Note. Check and, if necessary, top-up the engine oil level before beginning this test.
Note. Where reference is made to 'suitable equipment', this refers to standard workshop equipment. Refer to the operating instructions for your own equipment when performing any tests.
Pinpoint Test C
C1
CHECK FOR LOW ENGINE OIL PRESSURE
- Remove the oil pressure sensor, Refer to «Engine Oil Pressure (EOP) Sensor»(ref-311295-S10041752352009032500000) article.
- Connect a suitable oil pressure gauge in place of the oil pressure sensor.
- Start the engine and check for leaks at the gauge connection.
- Allow the engine to idle and monitor the oil pressure.
- Raise the engine speed to 2,500 RPM and monitor the oil pressure.
Is the oil pressure less than 0.50 bar (7.25 psi) between idle and 2,500 RPM?
C2
CHECK FOR LOW ENGINE OIL PRESSURE AT ENGINE SPEEDS GREATER THAN 2,500 RPM
- Raise the engine speed to above 2,500 RPM and monitor the oil pressure.
Is the oil pressure less than 1.0 bar (14.5 psi) at engine speeds greater than 2,500 RPM?
YES Pressure this low may indicate a problem with: oil pump, filtering, clearances within the engine. Check if there are any other indications of engine faults (noise, etc), refer to «Symptom charts»(ref-311296-S25177585502009032500000) .
NO Go to step 3 . → 3
C3
CHECK FOR HIGH ENGINE OIL PRESSURE
- Monitor the engine oil pressure at varying engine speeds.
Does the oil pressure reach 4.0 bar (58 psi)?
YES Pressure this high may indicate a blockage in the lubrication system. If this is not resolved, high oil pressure will lead to engine oil leaks and other failures.
NO If the oil pressure stays in the band between 0.50 bar (7.25 psi) and 1.0 bar (14.5 psi) this would be considered normal.
Scheme 20
- Inspect bearings for the following defects. Cratering - fatigue failure Spot polishing - incorrect seating. Imbedded dirt engine oil. Scratching - dirty engine oil. Base exposed - poor lubrication. Both edges worn - journal damaged. One edge worn - journal tapered or bearing not seated.
Exhaust Manifold - General Procedures (-Inspection)
- Inspect the cylinder head joining flanges of the exhaust manifold for evidence of exhaust gas leaks.
- Inspect the exhaust manifold for cracks, damaged gasket surfaces, or other damage that would make it unfit for further use.
Scheme 21
- Carry out a visual inspection. Clean the piston skirt, pin bush, ring grooves and crown and check for wear or cracks. If there are signs of wear on the piston skirt, check whether the connecting rod is twisted or bent.