Smoking at hot idle?

[turbofiat]

Car : 1987 Yugo GV
Engine: Fiat 1500cc
Turbo : T25 (from a wrecked Saab 9000)

My Yugo has developed this weird oil burning issue which started back in September. When this occurs:

1) After the engine has reached normal operating temperature
2) 30 seconds to 1 minute after stopping
3) Does not seem to smoke while going down the road, or under full boost
4) Does not smoke on a cold start

I finally pulled the T25 off my Yugo yesterday. Unlike the T3 that failed on my Spider, I have found no excess amounts of oil in either the compressor or the exhaust discharge. Nor is there any excessive shaft play.

The carbon buildup does feel different between the exhaust manifold collector and the discharge pipe. What is in the discharge pipe just feels softer. What I am trying to determine is I am feeling burnt oil or simply carbon buildup.

So other than that, I can't tell if the oil burning is from a leaking turbo seal or something related to the engine itself.

So assuming the oil burning is not related to the turbo seal, oil backing up in the drain hose from excessive backpressure in the crankcase, restrictive air cleaner, etc. what else would cause the engine to start smoking at normal operating temperature?

Normally a car will smoke when first cranked (say from leaking valve seals or worn rings) but will stop once it's warmed up and everything expands.

This car does not smoke when cold but after it's reached normal operating temperature. Also if I stop and get out and look at the tailpipe, I don't see smoke initially. It usually takes 30 seconds to a minute before it starts smoking while I am letting the turbo wind down.

That leads me to beleive the delay has something to do with oil puddling in the exhaust from a leaking turbo. Also I did not see any oil deposits on the spark plugs so that leads me to believe oil is being burnt in the exhaust system and not the combustion chamber.

I have a rebuild kit and figure it will be easier to rebuild the turbo before rebuilding the engine or even rebuilding the cylinder head. So I'm going to try this first.

This problem did not start progressively. It just cropped up one day back in September.

I supose another idea might be to let the engine run while the turbo is off the car and see if it smokes that way. Be sure to cap off the oil feed hose.

[Guy Croft]

Compressor end seals


G

[turbofiat]

Compressor end seals


G

I tried rebuilding this turbo last spring but it did not turn out to be a success as my T3 rebuild went on my 124 Spider. My Yugo started smoking again after about 1000 miles. So I purchased a new cartridge. I have not installed it yet. I wished I had done this to begin with.

The Volvo 240 T3 turbo I picked up at a car show for $50 and could have been used (no shaft play) but thought I would rebuild it just to see if I could do it. After rebuilding the T25 which came from a wrecked Saab 9000 I still found some slight shaft play which I was suspicious of.

I suspect sooner or later a cartridge (or shaft) will have to be replaced and can never be rebuilt do to the shaft wearing down. Although it looked good to me. This turbo probably had 150K miles on it when I put it on my Yugo.

Used to finding low mileage Saabs in the United States were hard to come by. Most had well over 200K miles on them. I don't know if they were just good cars or the people who bought them were high mileage drivers.

I know a guy who had a 1979 99 given to him by a lady who swears it had over 800K miles on it. He claims it is the highest reported mileage of any Saab.

She drove the car back and fourth from Tennessee to California several times. Eventually the engine wouldn't hardly run due to low compression. He swears the only major maintence the engine had done was a couple of headgaskets and valve adjustments. I saw the car but can't swear to it it had 800+K miles on it.