Hello everyone, after working on my car for a while and not really driving it too much , i finally put it together and runs like it never did before ( i had a lot of issues becouse i had a buch of vacuum leaks thru my intake manifold gasket) so a new problem appeared and a scary one. When i start my car cold and let it run for 2 min its all good but when i rev it up to 4000rpm it starts smoking pretty bad, blue/grey color and smells like oil burning. I did compression test (look at pic)
while doing the comp test i shined some light into the pistons and did see a lot crap on top of pistons unburned ,

I have shark vent installed, recently changed the oil , could too much oil couse that?
https://cimg5.ibsrv.net/gimg/rennlis...e5c9c292e3.jpg


1986 928s3 compression test

Does it still smoke when the engine is up to temp (oil pressure is at 2 bar when at idle) or only when the engine is still cold (2 mins running)?

The comp reading look to be OK, when was the last time you drained the Intake of oil (this is an 86 32v)?
Also these engines run rich when cold (13.4 AFR), so frequent cold starts and not letting them heat up leaves a lot of burnt fuel in the cylinders.

Smokes when hot too

What do you mean " draining the intake out of oil?

on the S3 the Plenums will build up some oil in them over time (it sits in the boxes), I usually see a good thimble or a bit more in each between oil changes.
If this is an S3 and not a ROW.

I do not have any oil in plenums but i did have oil in here
https://cimg3.ibsrv.net/gimg/rennlis...7f2f9ed619.jpg



This hose connects to bottom of filter box.


https://cimg6.ibsrv.net/gimg/rennlis...548ab928b1.jpg

Does it only smoke at speeds over 4K RPM?

I just rebuilt the intake on my 86.5 along with fighting the the sleeves to make sure they fit without leaking ( why did Porsche use such short center connectors)? .
When started it blew smoke for about 5 miles of driving before it went away and has not done it since.

Its smokes at all rpm after its ran for couple minutes.before i did the comp test i drove it for about 20 miles and maybe an hour total and its started smoking after about 30 min of driving . Could the engine oil weight be an issue? Lets say 0w40?

I'm not sure what oil weight is specified for your climate, but I'm betting it's not 0w40. FWIW I run 20w50, but I'm in South Florida, where it's never really cold, ever.

I'd be shocked if that had anything to do with the smoking issue, however...

Go with the heavier oil, 15w50 or 20w50, and see what happens. I'll put 5w40 in if driven during the colder parts of winter. Otherwise, it's the heavier oil including when stored.

The compression numbers look good, from a consistency standpoint. Still, it shouldn't blow that much oil smoke. It suggests a piston ring problem.

Also this happens when engine revs up . Dark oil like substance from that hose pointing up , so maybe thats relaated to the smoking since that hose connected to that valve to is connected to cat? I am changing my oil tomorrow to 15\50 so i let everybody know what happens , but i have added this product for ring issues and smoking, its basically super thick oil, ao i added 2 quarts of it and the smoking is reduced a lot and its aeird sometimes it never smokes , its really weird,
https://cimg4.ibsrv.net/gimg/rennlis...b964e414a0.jpg

That's an odd, and probably intended to be adjustable, fuel pressure regulator- think you might be overfueling?

Edit/Disregard: And it also looks like your 928MS coolant tank is leaking from somewhere when hot. Mine does as well. If that is the source of the fluid, then you may have blown oil collers in the radiator allowing oil to contaminate the coolant. do you get an odor in the cabin when it's smoking?

On second look, I see what you are saying about the hose from the diverter valve, and that there is fluid on the sealing edge of that hose. There was actually fluid inside of it? That seems tough to rectify unless something is connected incorrectly. That is fed by the air pump on the front of the engine, don't see how oil or other fluid could get in there absent some mis-routing. Unless above does hold water and it is spraying right into the air cleaner and the cleaner lid is badly busted up.

Yep that's the CAT Air Pump diverter valve and I for one don't see how that could be an Oil source.

When you first posted a pic of the oil coming out I figured it was in the air box and draining down into that valve.

So what does the Anti-freeze look like, is it clean?

Also you can have good compression and worn or stuck Oil rings, mostly seen on engines that have been run hot and low on oil and the oil can't splash up to lube the lower pistons.

Did you ever post pic's of the spark plugs?