Smoking 911, but not in a good way . . .
 

So I am driving my Targa on Mulholland yesterday, minding my own business.
I come to a stop at an intersection and all of a sudden notice clouds of blue smoke
billowing from the rear of the car!!! There was more smoke the next time I came to a stop, but then it cleared up.

It doesn't blow blue when accelerating or decelerating (classic tests for rings and guides respectively) so I am more than a little mystified as to the cause.

Has this happened to any of you before? And if so, what was the cause?

Car has 207K. Uses about a quart/700-800 miles, and pulls strong.

Are you talking thick like a smoke screen out of the exhaust? Or smoke that could be caused by a good leak onto the heat exhangers?

Give Motormeister a call :D

I was driving so couldn't see. But think it was out of the exhaust.
A few weeks ago I was trailing a friend - he in my car, me in his Evo - and my 911 smoked a little from the exhaust. Again, it was as he was idling at an intersection, not under power.

what does the engine look like - top & bottom?

same for heat xchgrs, muffler, etc....

Idling at an intersection is where a drop of oil would fall straight down onto the heat exchanger, rather than being whisked away while driving. To me, this sounds like a typical oil leak - especially since it started suddenly. Take a look underneath and see if there is a new dirty spot or even a few drops of oil. It doesn't take much oil to produce lots of smoke.

I'll check for oil on the HEs and elsewhere, but it hasn't leaked on the garage for a long time, and when I was behind it (see above) the smoke (possibly blue) was from the exhaust.
Is it possible for, say, worn guides, to cause smoke when the engine's not under load?

Happens to my 86 3.2 now and then, especially when I over fill it with oil.

Is it only when cold? COuld be beginnings of guides or seals. Often valve seals will leak only at specific time, but when hot and rpm up they will sork ok. Blue exhaust out of tailpipe like you described is oil, just a question of where from. A compression check and vacuum check could tell you. Do both cold and hot tests.

Yes, when it's warming up. It rarely smokes once up to temp.

Sounds like valve guides/seals. They expand when they warm up and stop leaking.

oil overfill ?
 

check your oil,make sure its not overfilled.

"the smoke (possibly blue) was from the exhaust."

you are certain that all the smoke emerged from the pipe interior?

not from dripping onto the top of something hot and having wind blow it out neat the pipe exit?

I've had leaks where no drips ever happened onto a floor - it just leaked onto the top of my exhaust system, then burned - so get in there with mirror & flashlight

- but you may need a valve job

Check your oil the proper way (search here for the procedure)...often times this happens when your oil is overfilled.

No, it only happens when it's up to temp (in fact it has never smoked on start up).

Again, this is happening intermittently at IDLE and not when accelerating or decelerating. And it's coming from the tail pipe and not the HEs. And I haven't overfilled the oil tank.

So my question is what could be causing this? And have any of you had a similar experience?

And more specifically - can worn guides cause oil smoke at idle? As I mentioned earlier, I have done the Pete Zimmerman-hold-it-at-4k- and-then-engine-break-test
and it doesn't seem to smoke.