Posted by David Sherman on Thursday, July 31, 2003 at 11:00PM :
What would cause the crankcase of a diesel engine to fill up with diesel? It's a Allis-Chalmers 3500 in a gen-set. It has only 1000 hrs on it. In the old days the culprit would obviously be a broken diaphragm on the cam-operated fuel pump, but this one has no such pump. It has 2 electric pumps instead. Engine turns over and doesn't sound like anything is seriously broken or flopping around inside. Haven't tried to start it of course. There is a small amount of very fine metal powder in the diesel I drained out of the crankcase, but that may just be "normal" wear from running a while with highly-diluted lube oil.
It has a Stanadyne injector pump. I don't know if something could break in it and leak fuel into the crankcase. Anybody familiar with the innards of those? I suppose if it blew a hole in a piston, the normal fuel injection would end up in the crankcase, but that seems unlikely. If an injector went nuts I would think that if the engine was running at the time it would just put out lots of smoke and keep running (roughly). If it went nuts on start-up it could maybe get into hydrostatic lock but then it wouldn't turn over. Any ideas? Tests to do before tearing it all apart? Thanks.
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