Probable Causes
- Dirty oil filter or dirty oil cooler
- Fuel in the engine oil
- Excessive clearance between the rocker arm shaft and the rocker arms
- Oil pressure relief valve that is stuck open
- Faulty oil pump or faulty oil pump suction pipe
- Excessive clearance between the crankshaft and the crankshaft bearings
- Excessive clearance between the camshaft and the camshaft bearings
- Faulty oil pressure gauge or faulty oil pressure sending unit
- Low engine oil supply
Recommended Repairs
Dirty Oil Filter or Dirty Oil Cooler
Check the operation of the bypass valve for the oil filter. Clean the oil cooler or install a new oil cooler core. Remove the dirty oil from the engine. Put clean oil in the engine.
Fuel in the Engine Oil
Check for fuel in the engine oil. Refer to Troubleshooting, "Fuel In The Engine Oil". Make repairs, as required. Remove the engine oil that has been contaminated with fuel. Install new oil filters. Put clean oil in the engine.
Excessive Clearance Between the Rocker Arm Shaft and the Rocker Arms
Check for proper lubrication in valve compartments. Install new parts, as required.
Oil Pressure Relief Valve that is Stuck Open
Clean the valve and the housing. Install new parts, as required. Check the bypass valve in the oil cooler and the bypass valve in the oil filter base.
Faulty Oil Pump or Faulty Oil Pump Suction Pipe
Repair the oil pump or replace the oil pump, if necessary. Check the oil pump suction pipe. Replace the oil pump suction pipe, if necessary.
Excessive Clearance Between the Crankshaft and the Crankshaft Bearings
Inspect the crankshaft bearings. Look for excessive clearance between the bearings and the crankshaft. Install new bearings, if necessary.
Excessive Clearance Between the Camshaft and the Camshaft Bearings
Inspect the camshaft and the camshaft bearings. Look for excessive clearance between the bearings and the camshaft. Replace the camshaft and the camshaft bearings, as required.
Faulty Oil Pressure Gauge or Faulty Oil Pressure Sending Unit
An oil pressure gauge or a sending unit that is faulty can give an indication of low engine oil pressure. Check the oil pressure gauge for proper operation. Use the 1U-5470 Engine Pressure Test Group to verify the accuracy of the oil pressure gauge. Install a new oil pressure gauge or install a new oil pressure sending unit, if necessary.
Low Engine Oil Supply
Ensure that the engine has the correct amount of oil.