- Too much oil consumption
- Low oil pressure
- High oil pressure
- Too much bearing wear
- Increased oil temperature
Excessive Oil Consumption
Oil Leakage On Outside Of Engine
Check for leakage at the seals at each end of the crankshaft. Look for leakage at the oil pan gasket and all lubrication system connections. Look for any oil that may be leaking from the crankcase breather.
Excessive oil leakage from the crankcase breather can be caused by combustion gas leakage around the pistons. A dirty crankcase breather will cause high pressure in the crankcase, and a dirty crankcase breather can cause the gaskets and the seals to leak.
Excessive oil leakage from the crankcase breather can also be caused by an oil level in the oil pan that is too high. This condition results in a crankshaft that drips oil. Take extra care to maintain the oil level under these conditions:
- The engine has been stopped.
- The oil has been allowed to settle for about 20 minutes.
See the Operation and Maintenance Manual, "Model View Illustrations" for information on the location of the oil level gauge.
Oil Leakage Into Combustion Area Of Cylinders
Oil leakage into the combustion area of the cylinders can be the cause of both blue smoke and excessive oil consumption. There are four possible ways for oil leakage into the combustion area of the cylinders:
- Oil leakage between worn valve guides (inlet) and valve stems
- Worn piston components or damaged piston components (pistons, piston rings, or dirty oil return holes)
- Incorrect installation of the compression ring and/or the intermediate ring
- Oil leakage past the seal rings in the impeller end of the turbocharger shaft
- Improper ring seating for a new or rebuilt engine
Too much oil consumption can also be the result if oil with the wrong viscosity is used. Oil with a thin viscosity can be caused by fuel leakage into the crankcase or by increased engine temperature.
Note: Excessively worn engine components and damaged engine components can be the result of any one of the following conditions:
- Improper maintenance of the oil
- Incorrect fuel system settings
- Poor maintenance of the air filter
Note: See these following publications:
- Operation and Maintenance Manual, "Engine Oil and Filter - Change"
- "TMI"
- Operation and Maintenance Manual, "Engine Air Service Cleaner Indicator - Inspect"
Measuring Engine Oil Pressure
| Tools Needed | ||
| Part Number | Part Name | Quantity |
| 1U-5470 | EnginePressure Group | 1 |
The engine oil pressure and a restriction in the oil filter can be measured with the electronic service tool.
An oil pressure gauge that has a defect can indicate low oil pressure or high oil pressure.
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| Illustration 1 | g00296486 |
1U-5470 Engine Pressure Group | |
The 1U-5470 Engine Pressure Group measures the oil pressure in the system. This Engine Pressure Group has a gauge that monitors the oil pressure inside the oil manifold.
Note: Refer to Special Instruction, SEHS8907 for more information on using the 1U-5470 Engine Pressure Group.
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| Illustration 2 | g00323033 |
Location of Oil Pressure Switch (1) Oil pressure switch. | |
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Work carefully around an engine that is running. Engine parts that are hot, or parts that are moving, can cause personal injury. |
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Oil pressure to the camshaft and main bearings should be checked on each side of the cylinder block at oil gallery plug (1). With the engine at operating temperature, the minimum oil pressure at full load rpm should be approximately 250 kPa (36 psi). Minimum oil pressure at low idle rpm should be approximately 100 kPa (14 psi).
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| Illustration 3 | g00296494 |
Engine Oil Pressure Graph | |
Low Oil Pressure
Crankcase Oil Level
Check the level of the oil in the crankcase. Add oil if oil is needed. The oil level can possibly be too far below the oil pump supply tube. This will cause the oil pump to NOT have the ability to supply enough lubrication to the engine components.
The Oil Pump Does Not Work Correctly
The inlet screen of the supply tube for the oil pump can have a restriction. This restriction will cause cavitation and a loss of oil pressure. Air leakage in the supply side of the oil pump will also cause cavitation and loss of oil pressure. If the bypass valve for the oil pump is held open, the lubrication system can not reach the maximum pressure. Oil pump gears with too much wear cause a reduction in oil pressure.
Oil Filter Bypass Valve
If the bypass valve for one or more of the oil filters is held open due to a restriction, a reduction in the oil pressure can be the result. Remove each bypass valve and clean each bypass valve. This allows you to correct the problem. You must also clean each bypass valve bore. Install new Caterpillar oil filters. New filters will prevent more debris from causing this problem.
Excessive Clearance At Engine Bearings Or Open Lubrication System
Components that are worn and components that have too much bearing clearance can cause low oil pressure. Low oil pressure can also be caused by an oil line or by an oil passage that is open, broken, or disconnected.
Piston Cooling Jets
When the engine is operating, piston cooling jets direct oil toward the bottom of the piston. This cools the piston. This also provides lubrication for the piston pin. A seizure of the piston will occur quickly if a jet experiences any of the following problems:
- Breakage
- Restriction
- Incorrect installation
Use the 5P-8709 Cooling Jet Alignment Tool to check the alignment of the piston cooling jets.
High Oil Pressure
Oil pressure will be high if the bypass valve for the oil pump can not be opened.
Excessive Bearing Wear
When some components of the engine show bearing wear in a short time, the cause can be a restriction in an oil passage. A broken oil passage can also be the cause.
An indicator for the oil pressure may show that there is enough oil pressure, but a component is worn due to a lack of lubrication. In such a case, look at the passage for the oil supply to the component. A restriction in an oil supply passage will not allow enough lubrication to reach a component. This will result in early wear.
Increased Oil Temperature
When the engine is at operating temperature and you are using SAE 10W30 oil, the maximum oil temperature is 115 °C (239 °F).
Look for a restriction in the oil passages of the oil cooler. The oil temperature may be higher than the normal oil temperature when the engine is operating. In such a case, the oil cooler may have a restriction. The oil pressure of the engine will not get low just because the oil cooler has a restriction.
Determine if the oil cooler bypass valve stays open. This condition will allow the oil through the valve instead of the oil cooler. The oil temperature will increase.
Indicators For Oil Pressure
| Tools Needed | ||
| Par Number | Part Name | Quantity |
| 1U-5470 | Engine Pressure Group | 1 |
An oil pressure indicator that has a defect or a sender that has a defect can give an indication of a low oil pressure or of a high oil pressure.
The 1U-5470 Engine Pressure Group can be used to make a comparison. Compare readings on the instrument panel's indicators with the oil pressure that is displayed on the electronic service tool.
The 1U-5470 Engine Pressure Group measures the oil pressure in the system. This Engine Pressure Group has a gauge that monitors the oil pressure inside the oil manifold.
Note: Refer to Special Instruction, SEHS8907, "Using the 1U-5470 Engine Pressure Group" for more information.