366 engine with gas getting into oil

Farmer-dave · January 16, 2005

I've got a 1976 366 chevy engine with gas getting into the oil. My oil level quickly rises after a oil change. We've replaced multiple fuel pumps originally thinking this was the problem. I'm sure it needs a rebuild, haven't done a pressure check yet. I don't know much about engines, If I had the heads redone would that possible solve my problem. I know removing the engine will be a pain, but I think I could remove the heads without taking the engine out

facn8me · January 16, 2005

Thats wierd. The only place it could get that much fuel from and run is the fuel pump. If the carb was puttin out that much it would'nt run or just barely. A suggestion would be put a electric pump on and see if that solves your problem. since you have tried a different mechanical pump already. How long does it take to raise the oil level?

Farmer-dave · January 16, 2005

Thats wierd. The only place it could get that much fuel from and run is the fuel pump. If the carb was puttin out that much it would'nt run or just barely. A suggestion would be put a electric pump on and see if that solves your problem. since you have tried a different mechanical pump already. How long does it take to raise the oil level?

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The truck get's run about 15 minutes each day. It's a cattle feed truck. Within a week it's at least a quart over, by a couple of weeks it's at least 3 quarts over. We've tried 4 or 5 different fuel pumps on it thinking that's what it had to be. And let me tell you putting them in is a pain in the butt. Would Napa or someplace be able to set me up with a electric pump. I really don't know how that would be set up on a carbureted engine

facn8me · January 16, 2005

Yes napa can set you up. you need a low pressure pump and possibly a pressure regulator. The main thing is to keep the pressure at 5-7 psi for best performance. and to keep it from flooding. Thats quite a bit o gas for the carb to be doin it. unless the carbs draining internally every time you shut it off and it never runs long enough to burn the fuel out of the oil. How does it start in the morning? does it crank alot and pumping doesn't seem to help till it's cranked a bit? Quadrajets have a problem with the bowl plugs leaking over tim. You also may have gas vapor come out the carb after it's shut off if the bowls are draining quickly. Just a few more thing I though of.

Farmer-dave · January 16, 2005

Well I may try the electric pump option, I'll have to price it out at Napa. The truck generally starts out pretty good. It obviously starts out better when there's less gas in the oil. I've tried thicker grades of oil and that really hasn't helped so maybe it is in the fuel pump. I just put a new carb on last year and I think it was a holly, if I remember it was cheaper to get the nickel plated version then the traditional one. Can you think of anything that could be physically wrong with the engine causing gas to get into the oil.

facn8me · January 16, 2005

theres only 2 places the engine can get gas the mechanical fuel pump (if the engine has one) or the carb. (fuel injection) I would guss the cost of parts for the elec fuel pump swap should be under $80 (cheap pump)

cantrma · January 17, 2005

You sure it's gas? It could be coolant. Water pump, intake manifold gasket, head gasket, cracked block.

Farmer-dave · January 17, 2005

Trust me it's gas. I've drained the oil enough. The smell is a give away. Antifreeze is clean.

Farmer-dave · January 17, 2005

Alright I went and bought a electric fuel pump. Pump plus 2 feet of 3/8 fuel line cost me $51. It wasn't too hard to get installed. I'll know in a few day's if this fixes the problem. I didn't get a pressure regulater because the napa people didn't think I needed it. If this doesn't work I'll try my old carburetor that I had rebuilt when I put my new one on. If none of this works I'm just going to go with a new longblock for the feedtruck. I'll be sure to post what happens. Thanks for the help!