diesel in base

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M

madelinemar

I own a nonsuch 36. It has a westerbeke 52 engine. I noticed lately the oil level climbing up on the dipstick. The engine runs fine and does not smoke. I changed oil and drained off twice as much as I put in. The oil is not milky. Hope someone can help. The engine is 1985. Thanks.
 

Rick D

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Jun 14, 2008
7,204
Hunter Legend 40.5 Shoreline Marina Long Beach CA
Fuel Pump

...is the first place I'd check. Assuming it is a manual pump, there is a diaphragm which, if ruptured, will allow raw fuel into the crankcase.
 
May 11, 2005
3,431
Seidelman S37 Slidell, La.
Oil level rising

If it isn't milky looking, it has to be diesel fuel getting into the crankcase. Unless of course your engine has found some way to manufacture motor oil. Seems to me that most of the Westerbekes use an electric fuel lift pump, but if you have a mechanical pump, that would be the first place to look. If you have an electric pump, about the only other place diesel could get in the oil would be a bad seal somewhere on the high pressure pump.
 
Feb 10, 2004
4,235
Hunter 40.5 Warwick, RI
Re: Oil level rising

I seem to remember hearing that diesel fuel in the crankcase oil could cause a run-away engine condition. If this is correct, the OP madelinemar has a potentially a dangerous situation if the source is diesel fuel. And I agree, if it isn't milky, it must be fuel.

Am I right or wrong?
 
Dec 2, 2003
1,637
Hunter 376 Warsash, England --
Fuel in Engine Oil?

As others have said this is probably fuel diluting the lubricant and is most likely the result of a fractured diaphragm in the fuel lift pump.
This oil will get splashed about in the crankcase due to the raised level and will get past the piston rings and then the engine will run on this 'fuel'. As there is no throttle valve in the inlet manifold (unlike a petrol engine) there is nothing to limit the engine rpm. The faster it revs the more oil gets past so the faster it runs. This is also not helped by the crankcase breather feeding into the inlet manifold - (for environmental reasons!)
A pal who is a boat salesman was waiting for a customer to arrive for a test sail and idly started the engine to let it warm up. It gradually increased speed until it was sounding as if it would throw a rod. He whipped off the engine compartment cover and stuck his hand over the air intake. That stopped it!
The cause was that they had simply overfilled the lube oil and this had frothed.
Moral - It this can even happen to a brand new engine which has excellent ring seals it can happen to anyone.
Suggest finding the cause before any further engine operation.
 
Jun 11, 2004
1,920
Oday 31 Redondo Beach
His hand!

I would suggest another way to block the air intake on a runaway engine. A large rag maybe. I would think th vacuum there could possibly put a hurt on your hand.
 
May 11, 2005
3,431
Seidelman S37 Slidell, La.
Run away engine

Your hand will do for a runaway to kill it. But do not use a rag. The likely hood of a rag getting sucked in is very realistic with a run away engine. If you are afraid of hurting your hand, anything flat will work. A stiff piece of cardboard, a small piece of wood, etc. But I would sure not recommend using a rag.
 
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