- Too much oil consumption
- Low oil pressure
- High oil pressure
- Too much bearing wear
- Increased oil temperature
Too Much 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. This can be caused by combustion gas leakage around the pistons. A dirty crankcase breather will cause high pressure in the crankcase. A dirty crankcase breather will cause the gaskets and the seals to leak.
Oil Leakage into Combustion Area of Cylinders
Oil leakage into the combustion area of the cylinders can be the cause of blue smoke. There are four possible ways for oil leakage into the combustion area of the cylinders:
- Oil leakage between worn valve guides and valve stems
- Worn components or damaged 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
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.
Measuring Engine Oil Pressure
| Tools Needed | ||
| Part Number | Part Name | Quantity |
| 1U-5470 | Engine Pressure Group | 1 |
An oil pressure gauge that has a defect can give an indication of low oil pressure.
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| Illustration 1 | g00293196 |
1U-5470 Engine Pressure Group | |
The 1U-5470 Engine Pressure Group measures the oil pressure in the system. This tool group has a gauge that monitors the oil pressure inside the oil manifold.
Note: Refer to Special Instruction, SEHS8524 for more information on using the 1U-5470 Engine Pressure Group .
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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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- Be sure that the engine is filled to the correct level with SAE 10W-30 oil. The information in the engine oil pressure graph is invalid for other oil viscosities.
- Connect the 1U-5470 Engine Pressure Group to the main oil manifold at location (1) .
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| Illustration 2 | g00346032 |
Oil manifold on the left side of the engine (1) Pressure test location. | |
- Obtain the normal operating temperature of the engine by operating the engine.
- Keep the oil temperature constant with the engine at the rated rpm, and read the pressure gauge.
Note: The engine oil temperature should not exceed 115°C (239°F).
- Locate the point that intersects the lines for the engine rpm and for the oil pressure on the engine oil pressure graph.
- The results must fall within the "ACCEPTABLE" range on the chart. A problem exists when the results fall within the "NOT ACCEPTABLE" range on the chart. The problem needs to be corrected. Engine failure or a reduction in engine life can be the result if engine operation is continued with oil manifold pressure outside this range.
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| Illustration 3 | g00293198 |
Engine oil pressure graph | |
Note: A record of engine oil pressure can be used as an indication of possible engine problems or damage. A possible problem could exist if the oil pressure suddenly increases or decreases 70 kPa (10 psi) and the oil pressure is in the "ACCEPTABLE" range. The engine should be inspected and the problem should be corrected.
Oil Pressure is Low
Crankcase Oil Level
Check the level of the oil in the crankcase. Add oil if oil is needed. The oil level can 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 Valves
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.
Too Much 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, 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
Oil Pressure High
Oil pressure will be high if the bypass valve for the oil pump can not be opened.
Too Much 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.
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 decrease 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.