87 911 smoking after driving hard

[stl87]

So I went to porshapalooza in Eureka Springs drove 300 miles without incident ( car has always ran great)

After going on a spirited 166 mile drive with a group of other porsches, mainly newer ones, pulled over to fuel up.

Sitting idling for a minute my car started blowing a large cloud of dark smoke for 20 30 seconds, then smoking just a little.

Was revving up and down for a minute or so. After letting it sit for a few minutes, I started it back up and it was smoking a little on start up but then cleared.

I parked it for the night to let it cool down. In the morning it seemed to smoke just a small amount on start up and then cleared.

Oil levels and temp levels all fine. Drove home with a periodic smell of oil that I never had before. Seems to be ok days late, put 1000 miles on the car and oil consumption is down 1 qt.

Any ideas what may have caused this?

I made an appointment with my local shop to check it out, but cant get in till after the holidays, hope I didn't hurt it.

[ganun]

Out the exhaust or not?

[Joe Bob]

Sounds like you sucked a little oil up into the intake. Where do you run you oil level at? Best to run it a little under 1/2 on the dip stick.

If the smoke bothers you, drive it only at night....

[zedsn]

Valve guides?

[Jherriott]

When you say spirited, you mean high G corners?

When you say Dark smoke... not blue? Like over rich smoke?

Jase.

[Trackrash]

Oil leak on exhaust?

[OffCamber00]

You didn't hurt the car by your spirited drive. In fact, most of these old cars do better the more they are driven.

That being said, what is the history of the car? Our Carreras have been known to suffer excessive valve guide wear that causes symptoms similar to what you describe. 20-30 seconds of smoke is not normal. Has a top end been done? If so, how long ago?

A small puff of blue smoke is normal on startup - but only after sitting overnight or for long periods.

My car smokes when i park it but only because it weeps onto my headers

[stl87]

Yes, out the exhaust.

Prior to leaving , I did top my oil level off to half way between the dots on my dipstick.

And spirited is putting it lightly, I was chasing a gt4 for half the day at triple digits on the straightaways, lots of g cornering and lots of shifting.

Beautiful roads in the ozarks, highly recommend to anyone who has not been.

Thanks for the replies

[wayner]

Dark smoke, spirited driving - carbon deposit letting go?

[stl87]

My car is a low mileage ( 60 thousand) 2 owner car.

The original owner hardly drove it over the last 10 years, I recommissioned it last year with fresh rubber, fluids,brakes and fixed lots of small items: gas gauge,wipers, etc.

The original owner kept up to date on all maintenance and fluid changes even when he didn't drive it. No top end work to date. I was fearing valve guides, but the car has not smoked excessively since returning.

[pmax]

Originally Posted by stl87

Yes, out the exhaust.

Prior to leaving , I did top my oil level off to half way between the dots on my dipstick.

The oil level has to be checked when warmed up and with the engine running.

[stl87]

Yes, I always check the oil level after warming up and running, but thanks for the reminder.

[pmax]

Sounds good. I usually check the oil level at the end of a driving session.

If you rev the warmed up engine and it smokes when the rpm drops, then your valve guides probably need work.

[stl87]

Great information, thanks ill check that prior to bringing in for service.

[stl87]

Well looks like one of the plugs was fouled, changed plug its running better, mechanic says looks like 'llI eventually need valve guides, keep driving until it gets worse

Any advice? Should I worry?

[Joe Bob]

Just keep an eye on oil consumption....run an ad for skeeter abatement.

Edit: If oil level is below 1/2 way AFTER A FULL WARM UP that is where it should be. DO NOT TOP off before a drive on a cold engine. Consider going to straight 30 or 40 weight next change if you are burning oil. Use Dino oil, NOT synthetic.

[petrolblue83911]

That sounds like over filled with oil

A long hard run will do more to heat up the oil and make it expand than it would to impact oil blow by, I'd check the oil levels again after driving the car and letting it get fully warm

[prschmn]

Are you sure that smoke you first saw was oil and not fuel? Hunting idle is often caused by a too rich mixture.

[Drisump]

I second the theory that you overfilled it. On most days, unless very hot, it takes at least 20 minutes of normal running to get to the maximum expansion of the oil in the tank. These cars will consume oil if ran above mid point on the stick.....At maximum expansion (ie. >20 minutes of normal running). Cheers

[DanielDudley]

Originally Posted by stl87

Well looks like one of the plugs was fouled, changed plug its running better, mechanic says looks like 'llI eventually need valve guides, keep driving until it gets worse

Any advice? Should I worry?

Figure out what oil you are running, and maybe switch. I'd start with Valvoline VR1 20/50 dino oil. It isn't uncommon for an air cooled engine to need new valve guides between 80 and 120 thousand miles. Often their best running years come after that top end refresh, but a thousand miles to a quart isn't too bad.

I'd want to do a compression test and leak down at some point before the overhaul, and if you have Dilivar lower head studs, you would want to switch to steel when you do the valves.

They say start the car and don't idle in the driveway. Drive and warm up the car before you get on it, and if it is really hot and you have been on it, drive it a mile or two normally to cool it down. The good news is that the replacement guides and studs are better than some of the originals, so it's really worthwhile when the time comes.

Sometimes fouled plugs are associated with bad plug wires or caps and rotors, routine service items. Also, most people here get the valve adjustment out of the way every 15,000 miles, so figure out when the last time that was done, and if you don't know, consider doing it.