Engine Diagnosis - Mechanical
WARNING: This page is about a different car, the 2005 Jeep Liberty. However, it is still accessible from the selected car via links, so may be relevant.
| CONDITION | POSSIBLE CAUSES | CORRECTION |
|---|---|---|
| LUBRICATING OIL PRESSURE LOW | 1. Low oil level. | 1. (a) Check and fill with clean engine oil. |
| (b) Check for a severe external oil leak that could reduce the pressure. | ||
| 2. Oil viscosity thin, diluted or wrong specification. | 2. (a) Verify the correct engine oil is being used. | |
| - | (b) Look for reduced viscosity from fuel dilution. | |
| - | 3. Improperly operating pressure switch/gauge. | 3. Verify the pressure switch is functioning correctly. If not, replace switch/gauge. |
| - | 4. Relief valve stuck open. | 4. Check/replace valve. |
| - | 5. If cooler was replaced, shipping plugs may have been left in cooler | 5. Check/remove shipping plugs. |
| - | 6. Worn oil pump. | 6. Check and replace oil pump. |
| - | 7. Suction tube loose or seal leaking. | 7. Check and replace seal. |
| - | 8. Loose main bearing cap. | 8. Check and install new bearing. Tighten cap to proper torque. |
| - | 9. Worn bearings or wrong bearings installed. | 9. Inspect and replace connecting rod or main bearings. Check and replace directed piston cooling nozzles. |
| - | 10. Directed piston cooling nozzles under piston, bad fit into main carrier. | 10. Check directed piston cooling nozzles position. |
| - | 11. Loose oil rifle plug with saddle-jet style nozzles | 11. Tighten oil rifle plug. |
| - | 12. Loose directed piston cooling nozzle. | 12. Tighten directed piston cooling nozzle. |
| LUBRICATING OIL PRESSURE TOO HIGH | 1. Pressure switch/gauge not operating properly. | 1. Verify pressure switch is functioning correctly. If not, replace switch/gauge. |
| ENGINE BREATHER RESTRICTED | 2. Engine running too cold. | 2. Coolant Temperature Below Normal |
| - | 3. Oil viscosity too thick. | 3. Make sure the correct oil is being used. |
| - | 4. Oil pressure relief valve stuck closed or binding | 4. Check and replace valve. |
| LUBRICATING OIL LOSS | 1. External leaks. | 1. Visually inspect for oil leaks. Repair as required. |
| - | 2. Crankcase being overfilled. | 2. Verify that the correct dipstick is being used. |
| - | 3. Incorrect oil specification or viscosity. | 3. (a) Make sure the correct oil is being used. |
| - | (b) Look for reduced viscosity from dilution with fuel. | |
| - | (c) Review/reduce oil change intervals. | |
| - | 4. Oil cooler leak | 4. Check and replace the oil cooler. |
| - | 5. High blow-by forcing oil out the breather. | 5. Check the breather tube area for signs of oil loss. Perform the required repairs. |
| - | 6. Turbocharger leaking oil to the air intake. | 6. Inspect the air ducts for evidence of oil transfer. Repair as required (slight oil residue is normal). |
| COMPRESSION KNOCKS | 1. Air in the fuel system. | 1. Identify location of air leak and repair. Do not bleed high pressure fuel system. |
| 2. Poor quality fuel or water/gasoline contaminated fuel. | 2. Verify by operating from a temporary tank with good fuel. Clean and flush the fuel tank. Replace fuel/water separator filter. | |
| 3. Engine overloaded. | 3. Verify the engine load rating is not being exceeded. | |
| 4. Improperly operating injectors. | 4. Check and replace misfiring/inoperative injectors. | |
| EXCESSIVE VIBRATION | 1. Loose or broken engine mounts. | 1. Replace engine mounts. |
| 2. Damaged fan or improperly operating accessories. | 2. Check and replace the vibrating components. | |
| 3. Improperly operating vibration damper | 3. Inspect/replace vibration damper. | |
| - | 4. Improperly operating balance shaft | 4. Inspect/replace balance shaft. |
| 5. Improperly operating electronically controlled viscous fan drive. | 5. Inspect/replace fan drive. | |
| 6. Worn or damaged generator bearing. | 6. Check/replace generator. | |
| 7. Flywheel housing misaligned. | 7. Check/correct flywheel alignment. | |
| 8. Loose or broken power component. | 8. Inspect the crankshaft and rods for damage that causes an unbalance condition. Repair/replace as required. | |
| 9. Worn or unbalanced driveline components. | 9. Check/repair driveline components. | |
| EXCESSIVE ENGINE NOISES | 1. Drive belt squeal, insufficient tension or abnormally high loading. | 1. Check the automatic tensioner and inspect the drive belt. Make sure water pump, tensioner pulley, fan hub, generator and power steering pump turn freely. |
| 2. Intake air or exhaust leaks. | 2. Refer to Excessive Exhaust Smoke. Refer to SMOKE DIAGNOSIS CHARTS . | |
| 3. Excessive valve lash. | 3. Adjust valves. Make sure the rocker arms are not bent. Replace bent or severely worn components. | |
| 4. Turbocharger noise. | 4. Check turbocharger impeller and turbine wheel for housing contact. Repair/replace as required. | |
| 5. Gear train noise. | 5. Visually inspect and measure gear backlash. Replace gears as required. | |
| 6. Power function knock. | 6. Check/replace rod and main bearings. |