Base Engine Misfire with Abnormal Valve Train Noise
| Cause | Correction |
|---|---|
| Worn, damaged or loose rocker arm | Inspect the valve rocker arms. Repair or replace damaged components as required. |
| Worn, damaged, loose or bent valve push rod | Inspect the valve push rods. Repair or replace damaged components as required. |
| Worn, damaged or stuck valve, carbon on the valve stem or valve seat | Inspect the valves. Inspect the valve guides. Repair or replace damaged components as required. |
| Worn, damaged or dirty valve lifter | Inspect the valve lifters. Inspect the camshaft. Repair or replace damaged components as required. |
| Worn or damaged camshaft lobe | Inspect the camshaft. Inspect the valve lifters. Repair or replace damaged components as required. |
| Worn, damaged or loose timing chain and sprockets | Inspect the timing chain and sprockets. Repair or replace damaged components as required. |
Base Engine Misfire with Abnormal Valve Train Noise
Engine Noise on Start-Up, but Only Lasting a Few Seconds
| Cause | Correction |
|---|---|
| Incorrect engine oil, viscosity | Install the correct engine oil and oil filter. Refer to Engine Oil and Oil Filter Replacement . |
| Incorrect oil filter, without anti-drainback feature | Install the correct engine oil and oil filter. Refer to Engine Oil and Oil Filter Replacement . |
| Worn, damaged, or improperly installed oil filter by-pass valve | Inspect the oil filter by-pass valve. Repair or replace damaged components as required. |
| High valve lifter leak down rate | Inspect the valve lifters. Repair or replace damaged components as required. |
| Worn, damaged, or improperly installed crankshaft thrust bearing | Inspect the crankshaft. Inspect the crankshaft thrust bearing. Repair or replace damaged components 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 | Verify oil pressure. Refer to Oil Pressure Diagnosis and Testing . Repair or replace damaged components as required. |
| Improper lubrication of the valve train components | Verify oil pressure. Refer to Oil Pressure Diagnosis and Testing . Inspect the valve rocker arms. Inspect the valve push rods. Inspect the valve lifters. Inspect the oil filter bypass valve. Inspect the oil pump and pump screen. Inspect the engine block oil galleries. Repair or replace damaged components as required. |
| Worn, damaged or improperly installed valve rocker arm | Inspect the valve rocker arms. Repair or replace damaged components as required. |
| Worn or damaged valve rotator | Inspect the valve rotators. Repair or replace damaged components as required. |
| Broken valve spring | Inspect the valve springs. Repair or replace damaged components as required. |
| Worn, damaged or stuck valves, carbon on the valve stem or valve seat | Inspect the valves. Inspect the valve guides. Repair or replace damaged components as required. |
| Worn or damaged valve guide | Inspect the valve guides. Inspect the valves. Repair or replace damaged components as required. |
| Worn, damaged or bent valve push rod | Inspect the valve rocker arms. Inspect the valve push rods. Inspect the valve lifters. Repair or replace damaged components as required. |
| Worn, damaged or dirty valve lifter | Inspect the valve lifters. Repair or replace damaged components as required. |
| Worn or damaged camshaft lobes | Inspect the engine camshaft lobes. Repair or replace damaged components as required. |
| Worn, damaged, improperly installed or loose timing chain and sprockets | Inspect the timing chain and sprockets. Repair or replace damaged components as required. |
| Worn, damaged or improperly installed timing chain tensioner, if equipped | Inspect the timing chain tensioner. Repair or replace damaged components as required. |
Upper Engine Noise, Regardless of Engine Speed
Lower Engine Noise, Regardless of Engine Speed
| Cause | Correction |
|---|---|
| Low oil pressure | Verify oil pressure. Refer to Oil Pressure Diagnosis and Testing . Repair or replace damaged components as required. |
| Detonation or spark knock | Verify the operation of the ignition controls system. Refer to Diagnostic System Check - Vehicle . Repair or replace damaged components as required. |
| Worn, damaged, or improperly installed accessory drive belt - severe cracking, bumps or missing segments in the accessory drive belt | Inspect the accessory drive system components. Repair or replace damaged components as required. |
| Worn, damaged, or improperly installed accessory drive system components | Inspect the accessory drive system components. Repair or replace damaged components as required. |
| Worn, damaged, or improperly installed crankshaft balancer | Inspect the crankshaft balancer. Inspect the crankshaft. Repair or replace damaged components as required. |
| Worn, damaged, or improperly installed engine flywheel | Inspect the engine flywheel. Inspect the engine flywheel bolts. Inspect the torque converter. Inspect the torque converter bolts. Inspect the crankshaft. Repair or replace damaged components as required. |
| Worn, damaged, or improperly installed torque converter | Inspect the torque converter. Inspect the torque converter bolts. Inspect the engine flywheel. Repair or replace damaged components as required. |
| Damaged oil pan, contacting the oil pump screen-An oil pan that has been damaged may loosen, improperly position, or restrict oil flow at the oil pump screen, preventing proper oil flow to the oil pump | Inspect the oil pan. Inspect the oil pump screen. Repair or replace damaged components as required. |
| Worn, damaged, improperly installed or restricted oil pump screen-An oil pan that has been damaged may loosen, improperly position, or restrict oil flow at the oil pump screen, preventing proper oil flow to the oil pump | Inspect the oil pan. Inspect the oil pump screen. Repair or replace damaged components as required. |
| Worn, damaged, or improperly installed piston-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. | Inspect the spark plugs. Refer to Spark Plug Inspection . Verify engine compression. Refer to Engine Compression Test . Inspect the cylinder bores. Inspect the pistons. Inspect the piston pins. Inspect the connecting rods. Repair or replace damaged components as required. |
| Worn, damaged, or improperly installed connecting rod bearing | Inspect the connecting rods. Inspect the connecting rod bearings. Inspect the crankshaft connecting rod journals. Repair or replace damaged components as required. |
| Worn, damaged, or improperly installed crankshaft bearing | Inspect the crankshaft bearings. Inspect the crankshaft journals. Repair or replace damaged components 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 Diagnostic System Check - Vehicle . Repair or replace damaged components as required. |
| Worn, damaged, or improperly installed engine flywheel | Inspect the engine flywheel. Inspect the engine flywheel bolts. Inspect the torque converter. Inspect the torque converter bolts. Inspect the crankshaft. Repair or replace damaged components as required. |
| Worn, damaged, or improperly installed torque converter | Inspect the torque converter. Inspect the torque converter bolts. Inspect the engine flywheel. Repair or replace damaged components as required. |
| Worn, damaged, or improperly installed pistons-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. | Inspect the cylinder bores. Inspect the pistons. Inspect the piston pins. Inspect the connecting rods. Repair or replace damaged components as required. |
| Worn, damaged, or improperly installed connecting rod bearing | Inspect the connecting rods. Inspect the connecting rod bearings. Inspect the crankshaft connecting rod journals. Repair or replace damaged components as required. |
| Worn, damaged, or improperly installed crankshaft bearing | Inspect the crankshaft bearings. Inspect the crankshaft journals. Repair or replace damaged components as required. |
Engine Noise Under Load