gas in oil

[ruffy]

I have a 1996 4.3 volvo drive with holley 2 brl carb electric fuel pump. If i run it for 5 to 8 hours my oil will go up about one litre on the stick. I changed needle and seat and still problem.does not leak when sitting put a shut off vale on.will gas leak by power vale when boat is runnig.

 

[Don S]

Re: gas in oil

I couldn't imagine how bad that engine must run for it to be rich enough to gain that much gas in the oil.
Are you sure it's gas in the oil, and not water?
If it indead is gas, not only do you need a complete carb overhaul to check everything, but I would sure be doing a compression test also. Somehow, you are getting an unreal amount of gas past the cylinders.

And test the fuel pump pressure also

 

[erie_guy]

Re: gas in oil

Ruffy,

I would agree with Don S that you may have a bad fuel pump (diaphragm). A cracked diaphragm can by-pass fuel leakage directly into the crankcase. Best of luck in finding this problem before more major engine issues arise.

As I remember years ago (30+), the mercruiser guys used a double diaphragm and vented the space between the diaphragms to the intake manifold. i.e. a bad fuel pump could be easily diagnosed be looking at the clear tube connecting the pump to the intake manifold. Fluids in the hose - get service ASAP. Not sure current engines have similiar failure modes.

erie_guy
Port Clinton, OH

 

[Don S]

Re: gas in oil

I would agree with Don S that you may have a bad fuel pump (diaphragm).

I never said anything about a bad fuel pump diaphram. He has an electric fuel pump that isn't even connected to the block. Couldn't happen.

 

[87 bayliner]

Re: gas in oil

too much pressure from the pump ? carb need 4- 7 psi from the pump. many electric pumps go over that psi. you may need a pressure regulator.also if you have a back fire out the carb it can rupture the power valve in that holley carb. though im not sure if a quart of gas can pass thru power valve then past the rings and end up in the oil.
j

 

[DreamBoater]

Re: gas in oil

I agree with Don S if it is gas it has to be running rich as hell, if you come to find out it actually is gas you have been seriously washing your cylinder walls down of all the oil and eating at the rings.Do the compression test or even a leak down just to make sure. Sorry to say you may need to open the check book on this deal sooner or later. Good Luck
Scott