Weird oil burning problem

My car has developed a weird condition. I wouldn't call it a problem. Not just yet.

The car is a 1980 Fiat Spider, I've had for 13 years. I turbocharged the engine about eight years ago. Here's some details:

2 liter DOHC, iron block, aluminum head, Garrett T3 turbo. The engine was rebuilt in 1993 but now has 70K miles on it. The rebuilt head has 5K miiles on it and the turbo about 10,000 miles.

Here's what it's doing. This condition only happens when the engine is cold but not all the time. There doesn't seem to be any other pattern.

I crank the engine up and it smokes like I have a leaky valve seal. But the car will continue to smoke then lay a trail of blue smoke for

1/4 of mile then all of a sudden it just stops smoking. By this time the engine is at normal operating temperature.

I've owned cars with leaky valve seals but they usually just smoke for a few seconds then stop.

The weird thing is this doesn't happen all the time. Here's some examples. Gaps betwen these days are days the car has not been driven.

Sunday morning: Smokes when started up and lays a trail for 1/4 mile. Two hours later. No smoke four hours later. Smokes for a couple of minutes after startup but never noticed a trail of smoke once I got going.

Monday morning. No smoke

Thursday afternoon. No smoke

Friday. No smoke, changed oil

Wednesday: Smokes at startup, lays a trail for 1/4 mile then stops. About 1/2 mile up the road, I accelerate and I see a puff of blue smoke. I drive for 30 miles. Never smokes again. Come home check oil. No lose of oil at all.

Thursday: No smoke

Friday morning: No smoke

Friday afternoon: Brief smoke at startup, but does not lay a trail of smoke once I start moving.

A couple of weeks ago I was looking for exhaust leaks. I found most of the leaks were coming from the exhaust flex joint. But one particular bolt on the turbo was really loose. There are about five bolts that hold the exhaust housing to the bearing housing. I had noticed that the turbo was leaking oil externally because everything above the bearing housing had a slight coating of oil. I tightened the bolt up. No more external oil leaks.

I seem to think it's one of three things.

I got a valve seal that is sticking. Perhaps when the camlobe has depressed that particular valve with the leaky seal, that is when the smoke happens. But looks like it would just smoke for a few seconds.

Turbo seal is allowing oil to enter intake pipe and when turbo heats the seal expands and quits leaking. I have found oil inside the intake pipe but I hear this is normal. But how normal? Could the loose bolt have something to do with this? Should I have loosened all five bolts then tightened each gradually? All the other bolts were tight.

Piston rings are rotating around due to normal engine wear and when the engine heats up, the rings expands and seals off.

I know this isn't eviornmentally friendly but I have the crankcase hose pointed directly to the ground. After driving on the highway and I come to a stop I can see some smoke coming from the hose. I would imagine this is normal for an engine with this many miles on it.

I haven't done a compression test. But would that tell me anything? The engine runs great none the less. I'm not having any driveabilty problems. Just an intermittant oil burning situation.

It's more embarrasing than anything to have someone behind you see your car smoking and they think, "There's one of those stinky little Fiats again".

So based on this information is there any way to figure out why the engine is smoking randomly?

Reply to
James
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I have seen those symptoms before on engines with broken rings. A small chunk of ring will vibrate itself up the side of the piston and make a hole. It then will puke out oil until the ring itself moves along and the hole gets closed so no more oil goes past. Drive for a bit and it opens again or closes again.

One MGB I saw had two like that until another chunk came up and actually punched a hole in the piston, then it 'really' smoked. Also an old Rover was like that and a really old Buick straight eight had almost all the pistons with edge bites.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's

James wrote:

Reply to
Mike Romain

Looks to me your turbo has some blowby until it gets good and warm. I don;t know about your vehicle, but straight 30W might solve the trouble or narrow it down , then perhaps go back to regular oil W. Just an idea...

Reply to
ed

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