In operation of a 2-stroke marine diesel engine, the following conditions are observed at different occasions:

Reasons:

1. Over-fueling of that cylinder: a faulty injector (dribbling or leaking), a worn fuel pump, or an incorrect fuel rack setting causing too much fuel to be injected, giving a high exhaust temperature.
2. Poor combustion: late injection, poor atomization, or a loss of compression (worn rings, leaking exhaust valve) causing incomplete combustion and a high exhaust temperature.
3. A leaking exhaust valve: hot gas passing through a leaking valve raises the exhaust temperature.
4. A scavenge air problem: reduced air supply to that cylinder (blocked air ports) giving a rich mixture and a high exhaust temperature.
5. A developing scavenge fire: the fire raises the exhaust temperature.

Actions:

1. Reduce the load on that cylinder (reduce the fuel pump index if individually adjustable) to bring the exhaust temperature down.
2. Check the injector (atomization, leak-off) and replace it if faulty.
3. Check the exhaust valve seating and the compression (draw card).
4. Check the scavenge air and the air ports.
5. If a scavenge fire is suspected, take the appropriate action.

Reasons:

1. Water ingress: a leak in the jacket cooling water system (e.g. a leaking cylinder head gasket, a cracked liner, or a leaking oil cooler) allowing water to enter the crankcase and raise the oil level.
2. Fuel ingress: a leaking fuel injector or fuel pump allowing fuel to enter the crankcase.
3. Condensation: water condensing in the crankcase (from blow-by) raising the level.
4. A leaking stuffing box/gland allowing water or oil to enter.

Actions:

1. Investigate the source of the ingress: check the cooling water system, the oil cooler, the fuel system, and the stuffing box.
2. Take an oil sample for analysis (water content, fuel content, metal content).
3. If water is found, locate and rectify the leak (e.g. re-tighten the head gasket, repair the liner, repair the cooler).
4. If fuel is found, rectify the fuel leak (e.g. replace the injector).
5. Drain the excess water/fuel from the sump and top up with clean oil.
6. Monitor the oil level and condition until the problem is resolved.