Puffs of smoke on closed throttle??

[Rob H]

I have owned my 1989 3.2 Carrera coupe for 7 months now, and what a joy it has been. The bug has truly bitten and although this was not the intention, I am now enjoying hill climbs and track days.
As a consequence I have been told that the car is blowing a big puff of smoke on closing the throttle after peaking out at maximum revs. There are a couple of busy sections on the hill climb, where the Wong chip lets it go to about 7,000 in second gear before I brake, with no time to upshift and downshift. The motor uses little oil and I fill it to just over half way between the marks with Fuchs oil. It pulls smooth and hard and has no other symptoms, but have had no compression testing on it.
The morning start up is clean, no smoke, with just a surging idle for 30 seconds some mornings.
I do not have service records, or an accurate mileage and the car has lived in Germany, Japan and now Australia.
Is this looking like valve guide replacement and is this better done sooner than later?
Over to you, gurus.

[stlrj]

Originally Posted by Rob H

... with just a surging idle for 30 seconds some mornings

Seems like it's running a bit rich which could explain your puff of smoke (oil past the rings) on overrun conditions. I would adjust the AFM to correct the mixture issue before dropping big money on a top end.


Cheers,

Joe

[javadog]

No, that looks like oil smoke. Pull the valve covers and check the play in the guides. The 3.2 motors can be prone to premature valve guide wear and if it gts bad enough, it can cause real problems.

JR

[stlrj]

Originally Posted by GH85Carrera

I noticed the same thing.

I had a lot of smoke with the Steve's chip. I put the OEM chip back in and the smoke is virtually gone.

exhaust smoke 1986 911


Amazing amount of info on "smoke" behind the Search key.

[porschenut]

The smoke is blue, indicating burning oil. That kind of smoke on throttle-off is a classic symptom of worn valve guides. I think a health check of your engine is advisable.

[Joe Bob]

Likely guides but you can try a heavier single grade oil....avoid synthetics.

[stlrj]

Originally Posted by porschenut

That kind of smoke on throttle-off is a classic symptom of worn valve guides. I think a health check of your engine is advisable.

If we are looking at the same pict, he was going up the hill on throttle. Still guides?

Originally Posted by Joe Bob

Likely guides but you can try a heavier single grade oil....avoid synthetics.

Might be better to fix the problem (and it may not be guides) than a cover up Band Aid approach.

[javadog]

Originally Posted by stlrj

According to the pict he was going up the hill on throttle. Still guides?

Yeah, he's going up a hill but he may be on the brakes for an upcoming corner. Can't tell that from a photo. Here's what he said in post #1 - "the car is blowing a big puff of smoke on closing the throttle, after peaking out at maximum revs".

JR

[stlrj]

Originally Posted by javadog

Yeah, he's going up a hill but he may be on the brakes for an upcoming corner. Can't tell that from a photo. Here's what he said in post #1 - "the car is blowing a big puff of smoke on closing the throttle, after peaking out at maximum revs".

JR

Maybe his brake lights aren't working either.

[javadog]

Originally Posted by stlrj

Maybe his brake lights aren't working either.

That's possible. Who cares?

Why not just consider what he said? Reckon he got that wrong, too?

JR

[Flat Six]

Originally Posted by porschenut

The smoke is blue, indicating burning oil. That kind of smoke on throttle-off is a classic symptom of worn valve guides. I think a health check of your engine is advisable.

+1
Closed throttle deceleration is a high-vacuum condition and tends to draw oil past valve guides and seals that wouldn't normally get past under other operating conditions.

Classic early warning signal of guide/seal wear.

HTH

[stlrj]

Originally Posted by javadog

That's possible. Who cares?

Why not just consider what he said? Reckon he got that wrong, too?

JR

But words can be deceptive and I sometimes find it hard to ignore what can be in plain sight.

Please forgive my obsessive compulsive nature.

[RWebb]

yes, classic symptom

the reason it is dangerous is that the valves are cooled (in part) by conduction of heat from the stem to the guides and thence into the head & a gap of air does not transmit heat well

w/o that pathway the valves can heat up too far, damage the metal of the stem, and break, sending the tulip down into the combustion chamber to rattle around and chew up the piston and chamber walls

beside the piston, cylinder and head damage it is even possible to damage the bearings if it all seizes up just right

you can always take the bet and see how long it will run before anything bad happens...

[Rob H]

Thanks for the responses.

Confirming, it only smokes on a closed throttle after an especially hard rev, and the photo with a lot of smoke is more inside front tyre lock up than exhaust (I have just spoken with the photographer). It doesn't smoke on acceleration.

I will be getting some tests and analysis done shortly. Thanks again and if anyone else has any more clues, I'm listening.

[Winter]

Here's a test you can easily do yourself. Drive down a very long hill, with car in gear, but not getting on the gas. As the bottom of the hill, put on the gas while looking in your rear-view mirror. If you get a nice puff of blue smoke, it's likely that everyone (including those with much more experience than I) who has suggested valve guides is correct.

I think think they're correct already, but this is a quick DIY "test" you can do that doesn't take much effort. No puff of smoke doesn't mean your guides are perfect, it just means that they're not far along enough in the wear department to allow the vacuum effect to really do its thing.

Good luck.

[Rob H]

Thanks Tom, will do.

[Jesset100]

Can't help on your problem but that looks like nice hill to climb.

[gregwils]

The best measure of how much smoke is "too much" is oil consumption. Porsche's standard is a minimum of 600 miles per quart, but most here will tell you that is getting pretty low. My car got down to 450 miles per quart before I did my motor.

Since you are new to the car, I would encourage you to keep accurate records, check the oil pretty frequently and add in full quart increments to make it simple. There are lots of very qualified people on this site to give you good information.

If your tracking shows oil consumption is less than a quart/1000 miles, don't worry about it the occasional puff.

[craigyirush]

+2 on gregwills' comment - the best indicator is your average oil consumption. If you are using 1 quart or less/1000 miles you are fine (even a but more is nothing to worry about).

As for those who are suggesting you should check the wear on your valve guides -how is this done? I've been told by two P-car mechanics that there is no way to do this with any degree of accuracy unless the heads come off.

[HarryD]

When I got my car, it was at 600 miles/quart.

FWIW, worn valves guides can be very dramatic. My car at 300 miles/quart, as I lift off the accelerator:



Yes, my valve guides were shot.