Base Engine Misfire with Abnormal Valve Train Noise
| Condition | Action |
|---|---|
| Loose, worn or damaged rocker arm | Inspect valve rocker arm and rocker arm shaft. Repair or replace all damaged components. |
| Loose valve rocker arm attachments | Inspect valve rocker arm and rocker arm shaft. Repair or replace all damaged components. |
| Worn or damaged pushrods | Inspect the pushrods for excessive wear. Inspect the pushrods for bent condition. Inspect the pushrods for broken tip. Replace pushrod if any damage is found. |
| Broken valve springs | Inspect valve springs. Repair or replace all damaged components. |
| Worn and/or damaged valve rotator | Inspect valve rotators. Repair or replace all damaged components. |
| Sticking valve | Carbon on the valve stem or valve seat may cause the valve to stick. Inspect valves and valve guides. Repair or replace all damaged components. |
| Worn or faulty camshaft lobes | Inspect camshaft lobes. If damaged replace camshaft and all lifters. |
| Excessive valve lash | Check the valve lash adjustment, and correct if above specifications. Repair or replace all damaged components. |
Base Engine Misfire with Abnormal Valve Train Noise
Engine Noise on Start-Up, but Only Lasting a Few Seconds
| Condition | Action |
|---|---|
| Incorrect oil viscosity | Drain the oil. Install the correct viscosity oil. |
| Excessive piston-to-cylinder bore clearance | Inspect the piston and piston skirt, connecting rod, and cylinder bore. Repair or replace all damaged components. |
| Damaged or faulty oil filter by-pass valve | Inspect the oil filter by-pass valve for proper operation. Repair or replace as necessary. |
Engine Noise on Start-Up, but Only Lasting a Few Seconds
Upper Engine Noise, Regardless of Engine Speed
| Condition | Action |
|---|---|
| Low oil pressure | Insufficient or poor oil supply to valve train. Perform oil pressure test. Repair or replace all damaged components. |
| Improper lubrication to the valve rocker arms | Inspect valve rocker arm and shaft, valve pushrod, oil filter bypass valve, oil pump and pump screen, and engine block oil galleries. Repair or replace all damaged components. |
| Excessive valve lash | Check the valve lash adjustment, and correct if above specifications. Repair or replace all damaged components. |
| Worn pushrod upper end ball | Inspect pushrod end ball. Repair or replace all damaged components. |
| Bent valve pushrod | Inspect valve pushrod and valve rocker arm. Repair or replace all damaged components. |
| Loose, worn or damaged valve rocker arm | Inspect valve rocker arm and rocker arm shaft. Repair or replace all damaged components. |
| Loose valve rocker arm attachments | Inspect valve rocker arm and rocker arm shaft. Repair or replace all damaged components. |
| Broken valve springs | Inspect valve springs. Repair or replace all damaged components. |
| Worn and/or damaged valve spring shims, seats, or keys | Inspect valve spring shims, seats, and keys. Repair or replace all damaged components. |
| Sticking valve | Carbon on the valve stem or valve seat may cause the valve to stick. Inspect valves and valve guides. Repair or replace all damaged components. |
| Missing or improperly positioned lifter guides | Inspect lifter guides. Repair or replace all damaged components. |
| Worn or faulty camshaft lobes | Inspect camshaft lobes. If damaged replace camshaft and all lifters. |
| Worn valve guide | Inspect the valves and valve guides. Repair or replace all damaged components. |
| Damaged or misaligned timing gears | Inspect timing gears. Replace all damaged components. |
Upper Engine Noise, Regardless of Engine Speed
Lower Engine Noise, Regardless of Engine Speed
| Condition | Action |
|---|---|
| Worn accessory drive components (abnormalities such as severe cracking, bumps or missing areas in accessory drive belt and/or misalignment of system components.) | Inspect the accessory drive components. Repair or replace all damaged components. |
| Low oil pressure | Insufficient or poor oil supply to crankshaft and connecting rod bearings. Perform oil pressure test. Repair or replace all damaged components. |
| Leaking and/or sticking fuel injection nozzle (A stuck fuel injection nozzle can cause a noise similar to a damaged piston, rod or rod bearing.) | Use the cylinder balance diagnostic procedure to help locate the cylinder that is the source of the noise. If you cannot locate the cylinder that is the source of the noise, diagnose the engine for mechanical damage. If it has been determined that the fuel injection nozzle is causing the noise, replace the fuel injection nozzle. |
| Loose and/or damaged crankshaft balancer | Inspect crankshaft balancer and balancer bolt. Repair or replace all damaged components. |
| Loose torque converter bolts | Inspect torque converter bolts and flywheel. Repair or replace all damaged components. |
| Loose and/or damaged flywheel | Inspect flywheel and flywheel attaching bolts. Repair or replace all damaged components. |
| Excessive piston-to-cylinder bore clearance | Inspect the piston, piston rings and cylinder bore. Repair or replace all damaged components. |
| Excessive piston pin-to-bore clearance | Inspect the piston, piston pin, and the connecting rod. Repair or replace all damaged components. |
| Misaligned or bent connecting rod | Inspect connecting rod and connecting rod bearings. Repair or replace all damaged components. |
| Excessive connecting rod bearing clearance | Inspect the connecting rod bearings, connecting rods, crankshaft and crankshaft journals. Repair or replace all damaged components. |
| Excessive crankshaft bearing clearance | Inspect the crankshaft bearings and crankshaft journals. Repair or replace all damaged components. |
| Oil pump pickup tube or screen bent or loose | Inspect the oil pump pickup tube and/or screen. Repair or replace all damaged components. |
Lower Engine Noise, Regardless of Engine Speed
Engine Noise Under Load
| Cause | Correction |
|---|---|
| Low oil pressure | Insufficient or poor oil supply to components. Perform oil pressure test. Repair or replace all damaged components. |
| Loose torque converter bolts | Inspect the torque converter bolts and flywheel. Repair or replace all damaged components. |
| Loose and/or damaged flywheel | Inspect the flywheel and flywheel attaching bolts. Repair or replace all damaged components. |
| Excessive piston-to-cylinder bore clearance | Inspect the piston rings for low ring tension, broken or worn rings, inspect cylinder bore. Repair or replace all damaged components. |
| Excessive crankshaft thrust bearing clearance | Inspect the crankshaft end play and crankshaft thrust bearings. Repair or replace all damaged components. |
| Excessive crankshaft bearing clearance | Inspect the crankshaft bearings and crankshaft journals. Repair or replace all damaged components. |
Engine Noise Under Load
Turbocharger Whine Noise
| Condition | Action |
|---|---|
| Some whine noise is normal. Compare to a known good vehicle. | |
| Leaking charge air cooler/pipes/hoses | Inspect for leaks in charge air cooler/pipes/hoses using J 46091 . |
| Worn turbocharger bearings | Visually inspect for evidence of compressor wheel to housing contact. If the turbocharger bearings are worn or damaged, inspect for a Turbocharger Lack of Oil Supply . |
| Intake system leaks or obstructions | Inspect for leaks or obstructions in the intake manifolds. |
Turbocharger Whine Noise
Turbocharger Hissing Noise
| Condition | Action |
|---|---|
| Air inlet leaks or obstructions | Inspect for leaks or obstructions in the turbocharger inlet pipes/hoses. |
| Leaking charge air cooler/pipes/hoses | Inspect for leaks or obstructions in the charge air cooler/pipes/hoses using J 46091. |
| Leaking or restricted exhaust system | Inspect for a leak in the exhaust system. Inspect for a restricted exhaust system. |
| Intake system leaks or obstructions | Inspect for leaks in the intake manifolds. Inspect for obstructions in the intake manifolds. |
Turbocharger Hissing Noise