20C_928

I just purchased a moss green '82 5 speed 928 which apparently has the the competition package and she has a 4.5L motor, everything is stock and in great condition except she makes a lot of bluish gray smoke around the 4000 RPM range. The previous owner told me the timing belt broke. Im not exactly sure what is causing her to smoke so badly. I would greatly appreciate any advice anyone has to offer as to what could cause a problem like this and what can be done to remedy it.

Also I appologize if this was asked before as it is late and all I found was info on a smoking 911.

SharkSkin

Oil ingestion? Make sure that the breathers are set up right, and make sure the oil isn't overfilled. You should be able to remove the air cleaner and look at where the oil breather comes in while someone revs the engine. If there's lots of blow-by carrying oil, then that's most likely the problem.

GlenL

That engine is non-interference so no piston-to-valve contact would be expected when the belt breaks. So you may be OK there. A few tests should be run:

Pull the spark plugs and look for black, tarry ones from oil getting into the cylinder.

Do either (or both) of compression test and leak-down test. This will help to find if the problem is blow-by past the rings.

Remove the hose from the oil filler cap and then run the engine. See how much exhaust is being force through the engine when you rev is slightly (maybe 3krpm). Will be some on all engines so hard to judge. Puffing is bad as that indicates individual bad pistons.

Search for "oil igestion" in the forum and email archives. These cars have a problem with that a the crank is too close to the pan so oil doesn't settle out. The problem feeds on itself rapidly as oil mist lowers octane which leads to detonation which leads to broken rings and then there's huge blow-by and smoke everywhere.

Then again, it could be a too rich mixture.

Best of luck.

SilverSFR

What is the procedure to lean out the mixture on an 1982 928

SilverSFR

GlenL

I believe you can't adjust it directly. (However, not my model of hands-on experience.) I would replace the 02 sensor if the blow-by test doesn't show much flow and there's no oil in the lower plenum.

Bill Ball

Shadetree mechanic-ism: Rich mixture smoke is black. Oil smoke is bluish.

Thaddeus

Coolant smoke is white.

heinrich

Vote oil ingestion. Check compression. Check breathers. Make sure it isn't overfilled.

Jim bailey - 928 International

It is also possible that the prior owner never used 4,000 RPM , there may be some accumulation oil old blowby residue in the entire intake system. If it continues to smoke,I would recommend doing compression and leak down tests to check the condition of the rings and bores .

GlenL

Innovative thinking! This would never have occured to me. Then again, I'll hit the rev limiter when commuting...

Barry Johnson

My S4 smoked pretty bad, from everywhere when I popped it on a dyno, and after a few runs, it ran better and stopped smoking.
I'd take the car out, and really crack the whip. See how it is after that. Good point Jim!

Bill Ball

Yes, an Italian tune-up can do wonders.

autochicago

Don't crack that whip too hard yet, as others mentioned, if it is detonating due to burning oil blowby you don't want to precipitate a more severe failure as mentioned by GlenL.

Mark

That would border on being sacreligious!

20C_928

Thank you all for your advice, I forgot to mention that she was rest down for a little more than 4 years, for what reason I can only speculate. Also, the car had only one owner which is an older lady so IMO its possible that she wasnt so hard on the car. I would like to put the engine under heavy load and see if that clears up or lessen the smoke output, but on the other hand I dont want to cause any further damage; Im a little embarassed to admit that I dont know how or how much PSI I should be looking for with the compression test; she wasnt overfilled with oil and the breathers looked alright to me.