| FAULT |
CAUSE |
CURE |
| Noisy valve gear (with correct clearance) |
1. Worn rocker or rocker shaft. |
1. Replace rockers or shaft. |
| 2. Worn cam follower tappet (OHC engine.) |
2. Fit new follower/tappet & camshaft. |
| Lack of compression |
1. Faulty valve seat, excessive wear in stem or guide. |
1. Recut seat and valve, fit new guide and valve. |
| 2. Faulty head gasket. |
2. Fit new gasket or reface head. |
| 3. Worn pistons, rings and bores. |
3. Either fit new rings, pistons and rings and rebore. If engine badly
worn then recondition engine. |
| Smoke from exhaust. Lack of power |
1. As above. |
1. As above. |
| 2. Blocked crankcase breather. |
2. Check breathing apparatus as above. |
| Piston slap |
1. Worn pistons, rings and bores. |
1. Engine overhaul. |
| Big-end knock |
1. Wear between big-end shell and crankshaft. Wrong torque on bolts. |
1. Depending on wear, fit new shells, regrind crankshaft and check torque. |
| Mains rumble |
1. Wear between main bearing shells and crankshaft. |
1. As above. |
| Cam follower (tappet) noise |
1. Camshaft worn or follower dished. |
1. Examine and replace followers or camshaft. Or both.. |
| Knocking when clutch depressed. Movement at crank pulley |
1. Excessive crankshaft end-float. Wear between crank and thrust washer. |
1. Fit new thrust washers and recheck clearance. |
| Clattering from front of engine |
1. Worn or slack timing chain, worn chain tensioner. |
1. Fit new chain and tensioner. Adjust chain where necessary. |
| Small-end or gudgeon pin knock |
1. Excessive wear between gudgeon pin and con-rod. |
1. Check piston assemblies for wear. |
| Lack of oil pressure |
1. Lack of oil. |
1. Install fresh oil. |
| 2. Faulty oil pump. |
2. Fit new pump. |
| 3. Blocked oil pick-up strainer. |
3. Clean pick-up. |
| 4. Faulty pressure-relief valve. |
4. Fit new relief valve. |
| 5. Blocked oil filter. |
5. Fit new filter. |
| 6. Excessive wear in crankshaft journals. |
6. Overhaul engine. |
| Oil leaks |
1. Sump gaskets or packings. |
1. Fit new gaskets. |
| 2. Front and rear crankshaft oil seal. |
2. Fit new seals. |
| 3. Rocker or camshaft gasket.. |
3. Fit new gasket. |
| 4. Oil filter. |
4. Check filter seal. |
| Lack of power (engine in good condition) |
1. Faulty ignition timing. Faulty sparking plugs, points or condenser.
Wrong valve clearance. |
1. Tune engine. |
