Engine Diagnosis - Mechanical
WARNING: This page is about a different car, the 2012 RAM Pickup and 2012 RAM Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.
ENGINE DIAGNOSIS - MECHANICAL
| 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. Refer to CAPACITIES AND RECOMMENDED FLUIDS, DESCRIPTION . | |
| (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. | |
| 6. If cooler was replaced, shipping plugs may have been left in cooler | 6. Check/remove shipping plugs. | |
| 7. Worn oil pump. | 7. Check and replace oil pump. | |
| 8. Suction tube damaged, loose or seal leaking. | 8. Check and replace suction tube and/or seal. | |
| 9. Loose main bearing cap. | 9. Check and install new bearing. Tighten cap to proper torque. | |
| 10. Worn bearings or wrong bearings installed. | 10. Inspect and replace connecting rod or main bearings. Check and replace directed piston cooling nozzles. | |
| 11. Directed piston cooling nozzles under piston, bad fit into main carrier. | 11. Check directed piston cooling nozzles position. | |
| 12. Loose oil rifle plug with saddle-jet style nozzles | 12. Tighten oil rifle plug. | |
| 13. Loose directed piston cooling nozzle. | 13. Tighten directed piston cooling nozzle. | |
| 14. Both J-jet and saddle jet style cooling nozzle installed. | 14. Install correct style jet. | |
| LUBRICATING OIL PRESSURE TOO HIGH | 1. Pressure switch/gauge not operating properly. | 1. Verify pressure switch is functioning correctly. If not, replace switch/gauge. |
| 2. Engine running too cold. | 2. Refer to Coolant Temperature Below Normal. Refer to DIAGNOSIS AND TESTING . | |
| 3. Oil viscosity too thick. | 3. Make sure the correct oil is being used. Refer to CAPACITIES AND RECOMMENDED FLUIDS, DESCRIPTION . | |
| 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. Refer to CAPACITIES AND RECOMMENDED FLUIDS, DESCRIPTION . | |
| (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. | |
| 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 electronically controlled viscous fan drive. | 4. Inspect/replace fan drive. | |
| 5. Worn or damaged generator bearing. | 5. Check/replace generator. | |
| 6. Flywheel housing misaligned. | 6. Check/correct flywheel alignment. | |
| 7. Loose or broken power component. | 7. Inspect the crankshaft and rods for damage that causes an unbalance condition. Repair/replace as required. | |
| 8. Worn or unbalanced driveline components. | 8. 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. Check for proper operation of over running alternator pulley. |
| 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 push rods are not bent and rocker arms, adjusting screws, crossheads, are not severely worn. 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. | |
| 7. High Pitched Squeal. | 7. Using soapy water solution check the EGR cooler to exhaust manifold joint. Check all clamps and hoses on the pressure side of the turbocharger |
OFF-IDLE ENGINE SPEED LOW DURING COLD START
Dependent upon engine coolant temperature, the Engine Control Module (ECM) will temporarily delay (limit) the maximum engine speed when the vehicle is not moving. For automatic transmission equipped vehicles, the maximum engine speed is temporarily delayed when the vehicle speed is less than one mph, and when the transmission selector is in either the neutral or park position. For manual transmission equipped vehicles, the maximum engine speed is temporarily delayed when the vehicle speed is less than one mph. This ECM feature is used to protect the engine turbocharger. By temporarily limiting the engine speed, the shaft speed of the engine turbocharger is controlled to a low speed. This delay in maximum engine and turbocharger shaft speed allows for sufficient oil lubrication to the turbocharger shaft bearings. Satisfactory oil lubrication of the turbocharger shaft bearings is important for long term turbocharger durability. The 6.7L engine speed is temporarily limited to 1, 200 RPM's when the above conditions are met. The length of time that the maximum engine speed is temporarily limited is dependent upon engine coolant temperature. Refer to the table to determine the amount of Time Delay.
NOTE:
The time delay values supplied in ENGINE TEMPERATURE VERSUS TIME DELAY are an approximation and may vary per application.
ENGINE TEMPERATURE VERSUS TIME DELAY
| ENGINE TEMPERATURE | TIME DELAY |
| - 35° F (-37°C) | 45.2 secs. |
| - 20° F (-28°C) | 34.6 secs. |
| - 10° F (-23°C) | 28.8 secs. |
| - 0° F (-17°C) | 24.2 secs. |
| + 10° F (-12°C) | 20.2 secs. |
| + 20° F (-7°C) | 17.0 secs. |
| + 35° F (2°C) | 13.0 secs. |
| + 45° F (7°C) | 10.8 secs. |
| + 55° F (13°C) | 9.0 secs. |
| + 70° F (21°C) | 7.0 secs. |