vtakk eg

ok I was out for a spin and pulled over to add alittle oil, since i had put about 500 miles on it since my last change. when i took off the oil filler cap i noticed some yellowish foamy goo on the underside of the cap, so i smelled it trying to figure out wtf it was, and it smelled of fuel ,or what it seemen to me.


FYI: my car was flooded and sat for a month wile flooded, but the oil was changed the day after i got it running. maybe somehow fuel got into the oil system, and got trapped in the oil coolers or something durring the service?

so my question is:

is this a sign that something is terribly wrong?

what is the yellow stuff and is it unherd of?

is it common th have a fuel smell there?

Sr20fd3st

the gas smell just means its running rich usually, maybe a little extra blowby from the richness...not too big of an issue.

the yellow stuff is usually a bad deal. coolant in the oil = about to blow or blown coolant seal. Is it thick, and does it reside in the filler neck and under the cap? make sure your PCV system is working. any white smoke coming from exhaust?
If it's a slow leak it'l take a while, but over time it'll signal the loow coolant buzzer. If it's runnign fine for now and not smoking you should be okay. But maybe start putting aside for a rebuild in the near future. Banzai Racing does an awsome job for 1500 bucks

Sgtblue

iTrader: (16)

The yellow goo is usually associated with moisture in the oil. Short drives in cool weather can bring it on. Fuel diliution (to one extent or the other) is also common. Mine is caused by the engine running rich in cool to cold weather until up to operating temp. It could also be sourced to leaking injectors or other sources but I don't think that's as common.

dgeesaman

iTrader: (7)

It smells like fuel because fuel does commonly get into the oil. It's one reason why many FD owners change the oil prior to the normal 3k interval.

Dave

DaveW

1. Absolutely not
2. Normal water condensation (as previous posts mentioned)
3. Normal (as per previous posts) - my oil always slightly smells like gasoline

Dave

Sr20fd3st

I always associated the yellow goo with a blown seal, since i still have the tramatic experience burnt into my memory...

vtakk eg

yeah my car sits out side in snow , and in driven in cold wheather and snow the last month that is pronly where the yellow comes from .

i only noticed the yellow goo under the cap didnt really look down the neck though

thanks alot

Railgun

In my experience, there's a point when it does become excessive. There have definitely been times when I'd change somewhere between 1.5-2k miles and there was enough fuel that it severely thinned out the oil. Perhaps it was just my condition at the time (motor has since let go) and not all that common, but I think it's definitely a concern.

DaveW

My oil has always smelled like gasoline, but it's never gotten diluted to the point that oil pressure was affected, or the oil appeared much thinner than normal. Of course, I still have the stock ECU.

Are you tuned particularly rich? I.e., why has your oil thinned so much?

Dave

Sr20fd3st

this would be so much eaiser if it was a piston motor...extra gas in oil = running rich and breaking the oil seal on the piston ring and going into the pan...or just bad rings and fuel goes down in there anyway. Now as it makes sense to me, the combustion chambers int eh rotary are completely enclosed and get their oil for the rotor surfaces by the oil injectors. i dont know the specifics on how the oil is channels thru the bearings on the stationary (?) gears/bearings that hold the E-shaft. i just dont see how running rich would cause fuel to get into the oil system. never quite understood that

DamonB

You're right; the sump is sealed from the engine in the rotary. On the other hand there is oil pumped through the eccentric and rotor bearings etc. Any gasoline escaping past the side seals and oil control rings etc on the side of the rotors can then intermix with the oil that is also present there.

The goo in the oil cap is merely condensation. It's open to the sump and is the highest point of the system so condensation collects there. If your car is driven hard the oil temp will become high enough to boil the moisture out of the oil and therefore no goo in the cap will be present.

My cap only has goo in it from about Dec-Feb

DaveW

Must be nice to be able to drive your car then...

We have about 2 feet of snow...

Dave