RBC

The engine in my '78SC is smoking quite a bit at idle, only when the engine is hot. It can sit for 3 days, and when started from cold, I don't get the typical puff of smoke. After it warms up however, it smokes at idle.

Should I concern myself with this in the near term?

Thanks!!

Steve Weiner-Rennsport Systems

RBC:

I would first of all ,check your oil level to ensure that its not overfilled.

Never, ever believe an oil level guage in any 911. Period. I have no clue what their true purpose is,...

Get the engine up to 180 deg on a level surface and check the oil with the dipstick.

Is the smoke blue or black?
How many miles on your car?

Does it run smoothly when its smoking?

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Steve WeinerRennsport Systems

RBC

Thanks for the reply!

The oil level reads about 2/3 between the low and high level marks on the dipstick.

The smoke is blue, the engine has around 80K miles on it, and it seems to be running fine. I looked in the airbox, and don't see oil contamination of any sort.

I hope this information helps.

Thanks!!

Steve Weiner-Rennsport Systems

Thanks, that helps,........

The oil level sounds just fine.

I would perform a hot compression test followed by a leakdown test on your engine.
This will pinpoint any compression losses from leaky valves, broken or worn-out rings and cylinders. The leakdown will show you where any problem lies.

How much oil do you consume per 1 thousand miles?
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Steve Weiner

Rennsport Systems

RBC

I'll have to check the oil consumption, but it takes me a long time to put 1,000 miles on the car!!

The compression checked out fine, but I haven't done a leakdown anaylsis.

For some reason it seems to have worsened when my new mechanic put Castrol 20/50 in the car. Could the brand of oil have anything to do with it?

Leland Pate

warm engine+ Thinner oil+ worn Valve guides= light blue smoke?

You said the compression test came out fine so I wouldn't suspect worn rings.

I'd bet on worn valve guides.

Just a place to look. Best of luck

Steve Weiner-Rennsport Systems

I too, would suggest that your guides & guide seals are worn out. Porsche updated the valve guide seals a few times since your engine was manufactured and the latest Viton ones are very durable and do an excellent job of oil control.

Using the latest phosphorus-bronze guides is also a great upgrade when the heads are done.

I'm no fan of Castrol products and we do not use them.

I would suggest checking your valve guides for wear and perhaps consider a valve job.
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Steve Weiner

Rennsport Systems