| Compression is too low |
Blown cylinder head gasket |
Replace the gasket. |
| Worn or damaged piston rings |
Replace the rings. |
| Worn piston or cylinder |
Repair or replace the piston and/or the cylinder block. |
| Worn or damaged valve seat |
Repair or replace the valve and/or the seat ring |
| Drop in engine oil pressure |
Engine oil level is too low |
Check the engine oil level. |
| Malfunction of engine oil pressure switch |
Replace the engine oil pressure switch. |
| Clogged oil filter |
Install a new filter. |
| Worn oil pump gears or cover |
Replace the gears and/or the cover. |
| Thin or diluted engine oil |
Change the engine oil to the correct viscosity. |
| Stuck (opened) oil relief valve |
Repair the relief valve. |
| Excessive bearing clearance |
Replace the bearings. |
| Engine oil pressure too high |
Stuck (closed) oil relief valve |
Repair the relief valve. |
| Noisy valves |
Incorrect valve clearance |
Adjust valve clearance |
| Thin or diluted engine oil (low engine oil pressure) |
Change the engine oil. |
| Worn or damaged valve stem or valve guide |
Replace the valve and/or the guide. |
| Connecting rod noise/main bearing noise |
Insufficient oil supply |
Check the engine oil level. |
| Thin or diluted engine oil |
Change the engine oil. |
| Excessive bearing clearance |
Replace the bearings. |