Horrific oil smoke at the track

[Quadcammer]

Gang,
I'm frustrated on this one.

I went to summit point in April and after mounting the NT01s, I came around a left hander, got on the gas in third, and when I lifted to shift to 4th, loud pop and ton of oil smoke. Ok, bad AOS right, no problem.

So I replace the AOS and head to NJMP this past weekend. Right from the start the car started smoking and in one session when I was really moving, I got black flagged cause it would smoke half way around the track. I'm not sure what else needs to be done here, but its frustrating.

So my plan is this:

New AOS warranty replacement
Replace PCV
Remove and inspect scavenge pumps for damage, improper orientation, etc.

Beyond that I have no clue.

Anyone have any ideas on other things to check? Very frustrating and a big waste of money when I have to come in early due to smoking.

Thanks very much.

[trygve]

A couple of thoughts:

- I've heard that residual oil in the intake from an AOS failure can linger. If the AOS blows, and leaves a lot of oil in the intake, it takes some time to burn off immediately after replacing the AOS. It's worth looking into the intake to see if it's dry or has a little stream of oil in it.

- The symptom of a big cloud of oil smoke during a 3rd-to-4th upshift is exactly what happened to my car. It was worse when exiting a corner just before shifting. You may want to do a compression and leakdown test. My test revealed 2 bad cylinders that turned out to have broken ring lands, which was causing a big shot of blow-by under certain conditions. I hope that's not what is happening with your car....

[Quadcammer]

Originally Posted by trygve

A couple of thoughts:

- I've heard that residual oil in the intake from an AOS failure can linger. If the AOS blows, and leaves a lot of oil in the intake, it takes some time to burn off immediately after replacing the AOS. It's worth looking into the intake to see if it's dry or has a little stream of oil in it.

- The symptom of a big cloud of oil smoke during a 3rd-to-4th upshift is exactly what happened to my car. It was worse when exiting a corner just before shifting. You may want to do a compression and leakdown test. My test revealed 2 bad cylinders that turned out to have broken ring lands, which was causing a big shot of blow-by under certain conditions. I hope that's not what is happening with your car....

Thanks for the info.

I cleaned out the intake plenums to remove any extra oil so I don't believe its residual.

Definitely a consideration. I'll do a compression test when I have a chance.

The weird thing on my car is that straight line I can be hard on the gas no problem, no smoke. On the street, never any smoke, ever.

On the track with hard turns, elevation changes, and banked turns, smoke city.

For reference, I have a 2qt deep sump, horizontal baffle, EBS vertical baffle, 997 return tubes, and a full flow filter adapter.

[thstone]

I'd like to add that my car had similar symptoms (smoking only in corners) and the cause was I had overfilled the oil level. We removed some oil at the track and the problem was solved.

And yes, I'd replace the AOS under warranty. You wouldn't be the first person to get a bad brand new AOS.

[Quadcammer]

I thought of that also. I started off a bit high on oil level but even after a few smoke sessions where the oil level dropped a bunch, it would still smoke.

I really think I may have a bad or upside down scavenge pump.

Btw thanks for your help with the sump parts. That stuff seems to work great on the pressure drop issue.

[Racer Boy]

You are on the right track with suspecting the cylinder head scavenge pumps. My car did almost exactly the same thing in left hand turns. To make a long story short, it did turn out that the passenger-side scavenge pump was not oriented correctly. I just pulled it out, put a new o-ring on it, and re-installed it in the correct spot. Problem solved!

[NewArt]

I had this problem in my previous Boxster. I replaced the sump baffle with an aftermarket one in aluminum and always ran my oil level at least 2 or 3 bars below full. Worked for me!

[Quadcammer]

Thanka was hoping you would chime in.

Scavenge pump on passenger side removed. No smoking gun. Some very minor scoring and a few pits from what looks like a bit of FOD, but no broken key drive and it was installed correctly.

Will post some pics for your input tomorrow, including one on orientation, but to my eye, it looks fine for a 110k mile georotor pump

[Racer Boy]

Hmm, that's disappointing that something simple like the scavenge pump orientation isn't it.

Those pumps are pretty simple, I'm not sure how they could fail if they are turning.

When I was trying to figure out what the problem was with mine, one the first lap of my first session at Pacific Raceways, they black flagged the session because they figured that I had blown my motor and oiled down the track due to the volume of the smoke. Pretty embarrassing. It would burn about two quarts of oil in one 2.25 mile lap if I didn't try to drive around the problem by coasting through left handers (which sucks if you are on a counter-clockwise track).

[Quadcammer]

Agreed, I was hoping for an obvious fix, but doesn't appear that way.

here are the pics of the pump. On the last one, the pointer shows the 1-3 mark for internal orientation, which appears correct to me.









Any ideas on how to test for an obstruction in the head to the crank drains? Compressed air?

Thanks.

[ToSi]

put the 996 swirl pots / return tubes back in..

[Quadcammer]

Interesting advice...which would result in having to cut holes in the baffle.

Can you elaborate as to why you recommend this?

[Quadcammer]

just to close the loop on this, compression in cylinder 2, 190. Compression in cyl 3, 95 when hot, 35 when cold.

hopefully will have a 3.2 on the way in the coming days.

[Racer Boy]

Ugh. That sucks.

[trygve]

Sorry to hear that. Condolences, I've been there.

3.2 sounds like a cool project!

[rastta]

Ugh - that sucks!