PCV Cause Gas in Oil?

[TalonJohn94]

Can a bad PCV in anyway lead to a smell of gasoline in oil?

I just want to narrow down the "Gas in Oil" problem I have after I do a compression/leak down test this weekend.

Yes I have wideband. 14.5 at idle, 10.5 - 11.2 during WOT.

Recently rebuilt head including valve seals and guides.

Thanks in advance.

 

[YanDsm]

Impossible, the pcv is plugged in the intake manifold before the fuel injectors. The only way gas can mix with oil is by the piston rings.

 

[TSITurbo95]

Piston rings. . .

 

[TalonJohn94]

Impossible, the pcv is plugged in the intake manifold before the fuel injectors. The only way gas can mix with oil is by the piston rings.

Ummm, the PCV is on the valve cover and a hose runs from it to intake manifold. And it draws out excessive crankcase pressure (and whatever doesn't get unburned and sneaks past the piston rings during a rich condition) back into the intake tract.

In a perfect world, air and fuel would stay on top of the pistons, and oil would stay below them. But of course it's not a perfect world. Because of the high cylinder pressures, some of the expanding gases are forced past the piston rings and find their way into the lower crankcase. These gases (commonly referred to as blow-by) consist of fuel vapor, partially burnt hydrocarbons, water vapor, and other nasty by-products of the combustion process. If these gases are not vented from the crankcase, they will eventually be absorbed into the oil and cause damage to bearings and other internal parts of the engine.

So I guess my question was more like ...

"Would an improvement to the PCV system such as a catch can reduce possible gasoline and other contaminants from entering the oiling system when piston rings are not perfect but compression/leakdown is well above service limits?"

I've read all the "Gas in Oil" threads and can't find a case where a PCV change/improvement improved their problem.

 

[Sebba]

I have yet to sniff a DSM's oil and not smell gas ...

 

[TalonJohn94]

Well I'm sure it takes a while to wash down cylinders and do significant harm but I still want to diagnose the problem.

 

[99gst_racer]

How did the compression/leak down test go?

 

[dberry]

alright i have a walbro 255 fuel pump installed on my car evo injectors and a 2g mass and a stock fuel pressure regulator, is it possible my f.p.r. is not working right? if i let my car set for a few days it starts right up, but if i drive it turn it off and try to start it well its pretty much flooded and its a bit difficult to start, plus after awhile my oil smells like gas, i don't drive it much and i change the oil after about 5 times of driving it, what do you guys think? i believe that there is enough pressure in the fuel lines after i cut the car off it seeps past the injectors.

 

[curt-s]

It's possible. You've also got a good chance of overrunning that stock FPR with a Walbro 255, causing a huge rich condition and washing the cylinders. The more and more you crank it without starting, the more fuel is sitting in the cylinders which will end up in the oil.

 

[dberry]

thanks for the advise, im just going to buy an fpr before i drive it again, any suggestions on a model or brand?

 

[DIMONDSTAR77]

aeromotive and fuelab are great brands. if you strapp
ed for cash you might find a deal in the classifieds.

 

[T is for TURBO]

I have yet to sniff a DSM's oil and not smell gas ...

You're more than welcome to come smell my oil, no gas smell



OP: I have had plenty of failed PCV valves in 3 different engines, and have never had oil that smelled like gas.
I have a feeling a compression test will tell you your rings are on their way out. Does your car use any oil?

 

[dberry]

no i definitly know my compression is just fine, my motor has less than 1000 miles on it, and i have yet to be hard on it, i built it myself so i know all of the internals are fine, everything was balanced within 1 gram, i don't burn any oil at all

my problem is my car floods after i shut it off thats why gas keeps getting in my oil

 

[jtmcinder]

No-one has asked if he's venting to atmosphere....

 

[alphamythos]

Venting is not going to matter on start up. Only on throttle release under boost. The fuel pressure regulator diaphragm may be the issue . With the 255 making it more noticeable . Cylinder wash is not a good thing. Before spending so much to replace the fpr . See if a dsm buddy has a stock one to put on and test. Should notice after a warm up and a few on and off attempts .
The Pcv will not be the issue.

 

[TalonJohn94]

Update: Received my US Plastics Check Valve.

So, on Wednesday I will have to to do a compression/leak down test. Then I'm going to check the condition of the PCV valve, install the plastic check valve, do an oil change, and check plugs.

I'll report back and go from there.