Boulder GT3

I'm a huge 911 nut and have a dozen or so with zero major issues. That said, I'm out of practice with the simple diagnostics.
Here's the set up- It's for my neighbors 2008 997 with 60K on it. Original owner who drives it easy. The car ran fine until Monday and oil smoke started pouring out the right rear tailpipe. I mean fog the street level.
I drove the car a couple of months ago and it drove fine. No smoke or early indicators. She put it on a flat bed and sent it to the dealer. The compression and leak down are below. While not optimum, the compression is fairly consistent. The leak down looks bad but it doesn't align with a sudden catastrophic change.
They bore scoped and found slight scoring in the bottom of cylinder 1.

Thoughts? Thankscompression test, we found cylinder #1 @ 250psi, #2 @ 260 psi, #3 @ 260 psi, #4 @ 260 psi, #5 @ 255 psi, #6 @ 250 psi. During a compression test the normal range should be around 300 psi.



Through further diagnoses we performed a cylinder leak down test. We found cylinder #1 @ 40%, #2 @ 30%, #3 @ 26%, #4 @ 30%, #5 @ 31%, #6 @ 31%.

Hella-Buggin'

Are sure it's just the right tail pipe and not both. If both it's possibly as simple as an AOS failure. If just the right I'd suspect something more dire. It might be time for a bore scope to see what's going on in there. If nothing is seen through the top spark plug holes, dig deeper and go in from the bottom of the cylinders through the pan as described by Jake Raby.

rsinghal3

^ Second this. Goodluck but those leak down numbers are a bit worrisome.

Hella-Buggin'

Yeah, I just dug up my leak down numbers and they were between 5-8%.

Quadcammer

with those leakdown numbers you have a major issue. The numbers are interesting, but you need to know where the leakage was going (into crankcase, through the intake or through the exhaust). This will tell you if the issue is rings or valves.

either the leakdown test was flawed or you have some real issues.

Iceter

While those leakdown numbers are worrisome, the sudden onset of the smoke screen makes me think this isn't rings. You said she took it to the dealer and they did the compression and leakdown checks but they stopped there? No diagnosis from them? That seems odd. Even if they don't know what is wrong, I'm surprised they didn't throw out something for her to pay for.

Boulder GT3

The sudden onset and relative consistency across the cylinders is what I can’t figure out. Could be a bad leak down test but I doubt it as that’s pretty basic.

the dealer wanted $7500 to do further diagnosis and another $8k if they had to split the cases to figure it out. That’s when she called me and I suggested to just get the car retrieved as you probably don’t want a rebuild done at the dealer anyways. She’s having to leave the country to get back to Toronto due to covad stuff. Bad timing for her. I’m just helping out as a fellow 911 nut.

BucketList

You won't be able to look at it again with her out of town, but I second HellaBuggin above. Need to ensure it's only one side and not both. Also need to ensure it's not water vapor. Does it smell like oil? If it's one side and oil, then it would tend to be more serious but possibly not catastrophic. A bad valve seal would do it but so would more expensive things like a cracked head or scored bore. Does it backfire at all? That would point to valve. If it's water, then head gaskets or cracked heads are typically the culprit. Ask her if she smelled oil smoke (more than usual) the last time she parked it before the first morning startup where it smoked bad. It could have scored on the way home and she didn't notice the smoke trail while driving. And yes, avoid the dealer. They don't see a lot of high mileage failures because everyone uses indy's. My local dealer had never done a pdk fluid change. That's done at 60k and they still hadn't actually done it. My indy has done hundreds. I wish her good luck.

Petza914

This sounds like textbook AOS failure to me where it starts sucking oil into the engine resulting in a smokescreen.

Best test to do next is a vacuum test with a manometer on the oil fill neck to see if the vacuum is way to high. The poo man's way to do this test is with the car running to try and unscrew and remove the oil fill cap. If it's really hard to do this due to the level of vacuum, the AOS has failed and needs to be replaced.

Start there before doing anything more invasive and expensive.

yelcab

I don't believe those compression and leak down numbers. 300psi compression? Where do you get those numbers? That seems awfully high. And leak down test without telling you where the leak is going? That's half the value of the test. And if you have that much leak down, 40% or more, you are not getting 250 psi compression.

Ryans Rebel

What is AOS?

darrenj

I agree leakage numbers do not make sense. With that much leakage the compression numbers should be lower.

Steph1

Air Oil Separator.

Quadcammer

I think the consensus here is that you need a 2nd opinion. The compression and leakdown numbers don't square and the smoking does sound AOS related.

rsinghal3

Any chance you can try the remove oil filler cap while engine running test to determine if there is excess vacuum?