Mark Hubley

Friday afternoon, after running three sessions at Summit Point during a PCA DE event, I noticed oil spilled on the front, passenger side of my motor, and a bit on the left, rear suspension. I had the car up on jack stands and was rotating the tires when I noticed the oil.

The car has about 90K miles, and about a month ago I had a shop replace the AOS. So the car has a new AOS. Prior to going on track, the engine oil was showing toward the lower mark on the dipstick. I added oil. Though I didn't intend to fill it so high, I ended up with the oil hitting the high mark on the dipstick.

After noticing the leak, I checked the oil and it was still showing on the high mark of the dipstick. Apparently it hadn't spilled much oil.

Given the oil spill, I decided to bail out on the rest of the DE weekend. I did not want to risk dumping oil on the track and causing problems for other drivers. I drove home from the track, about 100 miles. I had no problems on the drive home. After getting home, as best as I can tell the car did not leak any more oil, and the dipstick still reads at the high mark.

So, any ideas what happened? My best guess is that with the crankcase being full, and running on the track, maybe the AOS vomited out some oil somehow? Though I'm not sure how that would happen.

Could this be a one-time thing, and dropping the oil level will avoid such problems? Or do you think my AOS is compromised?

Maybe something other than the AOS?

I have not yet had a chance to put the car on my lift. Maybe I'll be able to see something. I'm not able to tend to things this week, but I guess I'll plan to bring the car back to the shop that installed the new AOS and have them take a look.

In the meantime, any advice will be appreciated.

5CHN3LL

Typically when the AOS ingests oil, the result is a smokescreen, not oil dribbled onto the engine. Search around here to learn about removing the oil filler cap to gauge how much suction is present while the engine is running if you're worried about the AOS.

I'd look elsewhere, like leaking cam covers, as the source of the oil.

Petersa9

It doesn't seem to be the in area, but a cracked filler tube or lose dipstick tube?

PORCAR

I'd be very surprised if it was the AOS, actually stunned. It should be fairly easy to spot once on a lift. Try not to get the undercarriage wet until then. What's the dispstick look like?

DTMiller

Are you sure it was oil and are you sure it was from your car? That's just a really weird combo of places. Too bad your weekend was cut short; I hear that someone won the free deer raffle.

Macster

Expelling oil onto the engine/ground is not a common AOS behavior. In fact I can't recall ever coming across this being reported.

Couple of things. One is a combination of very high oil level -- which is still preferred over a too low an oil level -- resulted in a big build up of oil under a camshaft cover and under positive crankcase pressure some of this oil was pushed out through a camshaft cover "seal".

Another explanation is the oil isn't engine oil but possibly power steering pump oil, rather make that fluid (Pentosin).

Best get the car in the air and give the area above where the oil appeared a good inspection in hopes you can spot where the fluid came from.

Mark Hubley

Got the car on my lift yesterday, and took a look. The picture isn't so great, but it appears that the greatest concentration of oil residue is on parts of the AOS. Also, those parts of the AOS appear to be the highest point of oil residue.




The pic was taken from under the driver's side, rear suspension looking back at the "front" of the engine. The tranny is to the left. You can see the AOS bellows in the center of the picture. The bellows and the part above it have a nice coating of oil, which then flows down over the front of the motor (mainly the front of the left side camshaft cover).

Here is a pic of an AOS:



The dirty bits I've referred to above are the upper left portions of the AOS in this picture--the bellows and the part sticking up to the right of the bellows.

In my car, it looks like all the connections are intact, but I wonder if oil blew out of the connection sticking up to the right of the bellows in the second picture? That's my guess at this point. That connection is just above and to the right of the bellows in the first picture.

The car is at an indy shop today. I'll update when I get word from them.

5CHN3LL

It's definitely not unusual to see oil in the area of the AOS. The unusual part would be having the AOS be responsible for puking out a large gob of oil on one specific occasion and then go back to being a happy AOS.

Looking forward to hearing what the indie discovers...

Mark Hubley

Word is the oil came from a loose crankcase breather line with a failed O-ring.