95 blowing oil out around the oil cap

[Green 912]

1995 stock class track car. motor and induction is stock except for headers back. Twice while on track it has belched some oil from the oil cap. Cap and all the plastic tubing to the oil tank has been checked and or replaced. did it again after 3 or so days on track with no issues. No undue ring blow-by and it does not happen all the time.

What to look for with regards the the case breather system? is there something that could limit the gasses from flowing from the case? This is a tough one as I can't reproduce the issue in the shop or on the street.

Any thoughts?

[Stuttgart951]

Bruce?

[Green 912]

Kurt, I am working on his car for him.

No ideas?

[Bill Verburg]

Here's the layout for the 993 oil system

I have over 1500 mi of track use this year alone and have never seen this.

Could the car have been overfilled?

[Green 912]

Have not seen it ether. There is something odd going on here and was hoping someone else might have. I have a 1995 motor in my track car as well but the venting system is not stock.
Thanks for the clip of the venting system.I have it in hard copy but this is good as I can use iot to send it to the owner.

I am picking the car up Sat and will be inspecting the ventiing system. Am hoping to find somthing pinched or the like.

[Jeff Burger]

are you talking about the oil cap that you take off when you fill the oil or are you talking about the "u" breather tube on top of the oil tank ?

jeff

[Arrowhead]

In my opinion I cannot see how oil will blow out the oil cap. The plastic oil cap screws onto the metel oil fill tube. The oil cap has an O-ring that when screwed onto the metal fill tube make a seal. If sealed properly like it comes from the factory it would need alot of pressure to blow by this seal even if you have a clogged oil venting system. I have seen where the O-ring is missing or in need of replacement or the top of the metal fill tube is bent. None the less after checking this I would check the rest of the venting system for proper installation, clogs, kinks, overfill, and the like.

[Bill Verburg]

Some of the 993tt guys have reported blowing oil out the fill when the wrong oil filter is used

[Jeff Burger]

On my 964 cup the metal lip on the filler neck hole that seals to the o-ring on the filler cap was pretty bent up and it would "leak" oil . after carefully straightening the lip to provide a flat and as uniform surface I was able to stop the leak. I am currently adding a breather system to my 964 gt4 race car because it was pushing oil through the pcv valve hidden under the u tube at the top of the tank. I suspect this is a result of the increased rpms since the cup never had this problem.

[Stuttgart951]

Really elementary question - but are the reservoir, pressure and temp gauges behaving abnormally?

[Green 912]

All things normal other than this issue. I have the car in hand and will put it on the lift tomorow afternoon to inspect the oil tank plumbing. I suspect / hope to find something with the PCV valve or othher venting issue.

[Stealth 993]

I had oil come out of my oil cap once, it was on a PCA tour during some spirited driving. Scared the hell out of me.

Turns out, when I added a bit of oil, I didn't seat the cap perfectly, & when I took a sharp right hander oil came out the fill & all over my engine.

[Green 912]

Found the problem. the check valve under the small U tube on the oil tank was jammed shut. thanks the the ideas and the oil flow chart!

[Lil bastard]

Glad you got it sorted.

I was going to suggest replacng the 'O' ring under the cap. The PN# is: 999.701.846.40/17

Cheers!