ENGINE DIAGNOSIS
| SYMPTOM | PROBABLE CAUSE | REMEDY |
|---|---|---|
| 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 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 |
| Low engine oil pressure | Refer to engine oil pressure drop symptoms above | |
| Thin or diluted engine oil | Change the engine oil | |
| Excessive bearing clearance | Replace the bearings |
ENGINE DIAGNOSIS CHART
INSPECTION
- Check the oil pan for cracks.
- Check the oil pan sealant-coated surface for damage and deformation.
Scheme 8
Required Special Tools
- MB990938: Installer Bar
- MD998285: Crankshaft Front Oil Seal Guide
- MD998375: Crankshaft Front Oil Seal Installer
- MD998776: Crankshaft Rear Oil Seal Installer
- MD998781: Flywheel Stopper
Scheme 9
Required Special Tools
- MB990938: Installer Bar
- MD998285: Crankshaft Front Oil Seal Guide
- MD998375: Crankshaft Front Oil Seal Installer
- MD998776: Crankshaft Rear Oil Seal Installer
- MD998781: Flywheel Stopper