pulled my pcv and it dripped gasoline

[scottmitchellrose]

rebuilt a 69 350 3 years ago with help from an expert. it's bored .060 over, so last one... the power was choppy on acceleration yesterday so I went to set timing and pulled pcv to get to that distributor bolt. it dripped of gasoline mixed in with the oil. panic set in... it has a new Holley 550 on it. any ideas? bad pcv? floats set too high from factory? ring blow by (ughh)?

[jumpsoffrock]

What does the oil in the sump look/feel/smell/taste like?

[HotWheelsFan]

Gas in oil can be caused from a leaking fuel pump diaphragm. Check oil level to see if overfull and if enough fuel gets into crankcase it can ignite and blow off valve covers with the force just from cranking the engine over. Use caution.

Bob

[scottmitchellrose]

Thanks for the help. Oil was slightly over filled, and dark/ runny when i changed it. I put in a new pcv and changed oil. The float level on the holley seems to be ok - i can't see anything in the clear window so must be below that. Not sure how to check the diaphragm on the fuel pump. It's a new one put in 3 years ago when the engine was rebuilt. It has less than 1,000 miles on it now.

[scottmitchellrose]

also- a mechanic friend thinks the float on my Holley is stuck. It's less than a year old, BUT I don't use the truck much so perhaps that too. I'll start there.

[LNP]

Did you check the float settings or just go with how it came? If you didnt you may wanna start there. Mechanical fuel pumps can develop issues and pump gas in the oil pan. If theres gas in the oil you'll need to change it a couple times to get all the gas out. As a guy that was a automotive diaognostic tech for over thirty years one thing I know for sure, new parts fail and some fail right out of the box. Even name brand
Forgot to add the power valve in the carb could be bad and leaking fuel into the intake.

[scottmitchellrose]

aha! I can see better today and the float level in the window looks to be 3/4 to the top. My adjustment is too high (nope- I did NOT adjust it when I put it on).
All of the ideas y'all gave were GREAT. I am so appreciative. I would have never thought to change the oil a few times, either.

I'll adjust the float first this pm and go from there/ see how it does and if all is good, change the oil again this week. I'll keep you posted.

Scott

[LNP]

Originally Posted by scottmitchellrose

aha! I can see better today and the float level in the window looks to be 3/4 to the top. My adjustment is too high (nope- I did NOT adjust it when I put it on).
All of the ideas y'all gave were GREAT. I am so appreciative. I would have never thought to change the oil a few times, either.

I'll adjust the float first this pm and go from there/ see how it does and if all is good, change the oil again this week. I'll keep you posted.

Scott

Its best to adjust the float with the sight plug out. All you want is it barely touching the bottom threads. Good luck I hope this solves your issue.

[fdbdw]

Not to thread jack but I've been following this thread I’m im really curious on a couple things, not questioning anyone I just can’t make the connection on a couple things.
The only 2 ways I can see getting fuel in the oil is either it leaks past the piston rings or the bowls overflow and some how makes its way out the PCV line and into the PCV valve ( I don’t know if that’s even possible). The combustion chambers and the PCV port are the only 2 connections between the carb and motor, outside of possibly a bad manifold seal.
Second, how would a fuel pump, pump gas into the oil pan? Only connection I see there is if the pump pushes fuel out the pump arm and into the pump arm rod chamber and making its way to the cam. Sorry to thread jack but I’m curious and I appreciate the knowledge.

[LNP]

You are correct on how a mechanical fuel pump lets gas into the oil. When a injector sticks open or a carburetor leaks gas into the intake for whatever reason it can wash down one or multiple cylinders which inevidently leads to gas in the oil. Remember two things the piston rings dont 100% seal think of blow by, and they actually dont press against the cylinder wall. They move on a oil film coated with ever stroke of the piston rod assembly. This is how a engine last a long time. The excessive gas not ony washes this fim off it mixes with the oil on the cylinder wall and eventually into the oil pan. Gas being thin it can follow the cross hatch on the cylinder wall and work past the rings this way as well. Its weird I know but after 30 plus years in the automotive repair field I have seem some strange things I will never beable to expalin.

[Ironangel]

Originally Posted by fdbdw

Not to thread jack but I've been following this thread I’m im really curious on a couple things, not questioning anyone I just can’t make the connection on a couple things.
The only 2 ways I can see getting fuel in the oil is either it leaks past the piston rings or the bowls overflow and some how makes its way out the PCV line and into the PCV valve ( I don’t know if that’s even possible). The combustion chambers and the PCV port are the only 2 connections between the carb and motor, outside of possibly a bad manifold seal.
Second, how would a fuel pump, pump gas into the oil pan? Only connection I see there is if the pump pushes fuel out the pump arm and into the pump arm rod chamber and making its way to the cam. Sorry to thread jack but I’m curious and I appreciate the knowledge.

The fuel overflows the bowls and runs down the carb throat into the intake manifold and right into the cylinders past the valves. The mechanical pumps have a rubber diaphragm actuated by the pump lever, and the lever actuated by the rod from the cam. When that diaphragm wears out or gets a hole in it, fuel can get pumped directly into the crankcase.

[fdbdw]

Originally Posted by LNP

You are correct on how a mechanical fuel pump lets gas into the oil. When a injector sticks open or a carburetor leaks gas into the intake for whatever reason it can wash down one or multiple cylinders which inevidently leads to gas in the oil. Remember two things the piston rings dont 100% seal think of blow by, and they actually dont press against the cylinder wall. They move on a oil film coated with ever stroke of the piston rod assembly. This is how a engine last a long time. The excessive gas not ony washes this fim off it mixes with the oil on the cylinder wall and eventually into the oil pan. Gas being thin it can follow the cross hatch on the cylinder wall and work past the rings this way as well. Its weird I know but after 30 plus years in the automotive repair field I have seem some strange things I will never beable to expalin.

Awesome, thank you

[scottmitchellrose]

I adjusted both bowls on the Holley. Also added a fuel pressure gauge- it's around 10!!!! Way too high. I don't see any fuel leaks- but haven't pulled the fuel pump off (engine has less than 1k on it post rebuild- all new parts).
Seems i need a fuel regulator as a start.

[scottmitchellrose]

it's a new Holley 550 with a braided dual fuel line feeding both bowls. Any recommendations on a regulator? Thanks

[LNP]

Originally Posted by scottmitchellrose

it's a new Holley 550 with a braided dual fuel line feeding both bowls. Any recommendations on a regulator? Thanks

I always use a Holley regulator