gas in crankcase....still....

[lasvegaspatriot]

OMC 4.3L, holley 2bbl, electric fuel pump. refresh your memories... rebuilt leaking carb, ran rough and no power (2500 max RPM)on water. after 1 hour oil level went up approx 1 gal(gas). I have since changed the oil and rechecked the carb rebuild. Compression check showed avg. psi of 155-168 (perfect).checked ignition components new plugs cap rotor. putting out good spark. ran tonight at home... 5 MINUTES GAS STILL GETTING INTO OIL... ENOUGH TO LIGHT THE DIPSTICK ON FIRE.. IM GETTING DISGUSTED... please help! thanks

 

[Don S]

Re: gas in crankcase....still....

Have you checked the fuel pump pressure?

 

[lasvegaspatriot]

Re: gas in crankcase....still....

not yet. how would this cause gas to get into the crankcase?

 

[LuckyPenny]

Re: gas in crankcase....still....

if one of the diaphrams is bad the fuel will leak into the crankcase. I had the same problem not too long ago, picked up about a qt an hour into the oil. It will kill the engine if let to run. The gas may not explode, but it will thin the oil. Does your oil turn black really quick? the gas is actually cleaning out everythink and not leaving any oil on the parts. Your bearing will be the first to go. do not run the engine anymore until you change the pump.

 

[tommays]

Re: gas in crankcase....still....

i would say you carb is dumping a LOT of gas in its just a question of why<br /><br />

Have you checked the fuel pump pressure?

i would follow dons advise he is pretty smart <br /><br /><br />tommays

 

[KaGee]

Re: gas in crankcase....still....

Originally posted by Luckypenny:<br /> if one of the diaphrams is bad the fuel will leak into the crankcase.

He has an electric fuel pump!

 

[lasvegaspatriot]

Re: gas in crankcase....still....

I HAVE AN !ELECTRIC! FUEL PUMP. I just went out this morning determined to take something apart. I was looking to pull the intake manifold.off came the carb and when I looked down the hole the manifold had puddled gas in the bottom of it. question is if the carb is dumping too much fuel when running can it get past the rings without burning. also when running Im getting what looks like unburned gas in the water runoff. do I just have to breakdown and buy a new carb?? thanks

 

[lasvegaspatriot]

Re: gas in crankcase....still....

also the old plugs were heavily fouled with dry carbon and the new ones have started, (showing a rich condition)...and no signs of oil getting into the cyliders. should that tell me ( along with the good compression test) that I dont have a crack or blown gasket etc. in the engine but that this is probably just a carberator or other external component issue??

 

[flashback]

Re: gas in crankcase....still....

Im with Tommays on this one, rebuild/replace the carb...sounds like the float is sticking,dirt in the needle, out of adjustment etc...how about the choke is it opening fully?......

 

[lasvegaspatriot]

Re: gas in crankcase....still....

I rebuilt the carb already, havent been able to adjust the choke but when I move it by hand I cant get it to run right either. I think its just gonna have to be a new carb... now I just have to explain thi$ to the wife.

 

[LuckyPenny]

Re: gas in crankcase....still....

Sorry to burst anyones bubble, but it is inconseivable for a gal of gas to get into the oil, past the rings; even with dead cyl, through the carb in an hour or less and still have the engine run.

 

[lasvegaspatriot]

Re: gas in crankcase....still....

Luckypenny, I know its inconceivable, that why its driving me so crazy. All or part of that gallon of gas may have got into engine before I ran it. It had a fresh oil change when I parked it in March. I only noticed the overfill after running it for an hour or so. what I cant figure out now is why its still getting in. I even test floated the float.

 

[wjcheeth]

Re: gas in crankcase....still....

Can I ask a silly question, where are your gas tanks? I had an old boat with the tanks in the sides, when they were full, the gas would siphon through the carb (bad needle valve) and flood the crank. Good luck

 

[rodbolt]

Re: gas in crankcase....still....

also with a holley if the powervalve is bad or the wrong gasket used it will dribble raw fuel into the intake tract. also a leaking needle valve will do it as well. does your carb have externally adjustable needle/seat assy's?

 

[lasvegaspatriot]

Re: gas in crankcase....still....

you guys are right, the only reasonable explanation is a bad needle valve or float. since i replaced the valve during the overhaul the the float must be bad. I hope this is it. thanks all of you for your help, and ill post the results by this weekend. P.S. if anyone comes up with another thought let me know.