Another oil overfill question

Maybe somebody can help me with this one. I recently had some work to my 91 C2 done by the dealer, including an oil change. Afterward, the oil level guage was higher than before (just about at the top when warmed up), and the dipstick was reading pretty much at the max line. The next week the weather warmed up more and the engine ran a little hotter. Last saturday morning I noticed oil under the car. Reaching my fingers up, there was a pool of very fresh oil in the forward pan (not the one under the engine, but the plastic one under the transmission). The oil level is also down a little lower, about 3/4 between min and max.

I took the pan off, but couldn't find where it was coming from in the engine or oil lines. I cleaned everything off and ran it hard and found no leaks. I am thinking it "coughed" it up because it was overfilled, but how do I confirm this? The air filter box was totally clean and dry. There has been no smoking or funny smells. I ran autocross on Sunday with no unusual indications. Where might the oil have come from?

Thank you in advance,
Tom

Hi Tom !

This problem just about drove me to drink.

I just got my C2 in Oct last year and when I had the car checked out there were no oil leaks. They did a service on it and apparently over filled with oil. The oil was WAY over the top hash mark when I checked it a week later.

I drained out the excess and didn't think much more about it until I found oil all over the engine pan. I saw it coming out between the #1 & 3 cylinder and I thought I was had by the guy that sold me the car and that it had the leaking head problem.

I looked for the oil leak for weeks. Almost every night I would take the pan off and see if I could find where it was coming from but it just kept dribbling - not a lot but enough to make me think it was the heads.

All this time I was looking UNDER the car ! So one day I got my digital camers and reached around the back by the airbox and snapped a few pix of the area. WOW ! There was oil all over everything ! I cleaned the engine off with cleaner and in a few days it came back. It drove me nuts ! I couldn't see anything leaking AND the oil level was THE SAME !!

Then one day I was at my mechanics place and we were talking about my "new" car. I told him about the weirdness of it all and he showed me the lines going to the oil tank in the engine area.

The LOWEST hose going in the tank is the one that goes to the emissions vapor recovery in the intake. The overflow is a good two inches ABOVE IT ! So, when you overfill the oil tank it goes into the air plenum long before it gets to the overflow hose !!

Now what you have is oil (liquid and vapor) going into the air plenum and it settles to the lowest point - the secondary plenum. (Kinda` like the secondarys on a 4 barrel carb ! It only get used when the vacuum drops low enough to call upon)

It will just sit there - UNTIL - it starts to drip out of the butterfly valve shaft that control the secondary plenum. This is where it was coming from and why the oil level never went down. The oil was sitting on the bottom portion of the air plenum and leaking out of the valve seal. (I have some great pix of all of this !)

There are only two ways to fix this. One is to remove the intake and clean it out (read EXPENSIVE) the other way is to use the secondarys a lot to force it out of the lower tube. I ran an autocross where I was into the secondary all day and since then absolutely NO oil leaks.

Long winded answer I know but some weird stuff happens to these car sometimes and it takes someone who has gone through it to let you know you not alone out there !



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Tom Sharpes
90 C2 Targa
http://members.rennlist.com/myc2

team5150

I think I may have the same problem.

How do you "use the secondarys alot"?



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Daryl 91C2 Targa

anyone?

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Daryl 91C2 Targa

With your right foot.