What would a puff of smoke mean upon starting a 993?

I see it on a lot of cars and I'm curious. Worn valve guides? Something else?

 

It be meanin you spliff is lit maaaan!

 

New Pope?

Seriously, AFAIK this is not uncommon and not a cause for concern as long as it doesn't last. A little oil pools in the horizontal cylinders while the engine's at rest.

 

It means you've got a nice healthy car.........

Seriously, I've seen it on virtually every air cooled 911 I've come accross. Sometimes it eminates from both tail pipes, sometimes from one and sometimes from the other - go figure....

The best explanation I've ever had is oil collecting in the exchangers. On mine you sometimes get a slight smell of oil for a second when you turn the heater on. I like to think it's character!

Regards

Oliver

 

It means it has been sitting for a few days.

 

After having seen a warbird (a Corsair at Hahnweide) start up, I strongly believe a little puff of smoke is justified for any air cooled engine. The fog created by the Corsair was quite impressive and I believe the tower had to shut down traffic on the runway nearby for a while...

Seriously, I would care to know where the oil for this little puff comes from, no matter how little and common this puff is. On mine I have not observed this, yet, but I may have overlooked it.

Best regards,

Felix

 

 

Let the engine idle for 30 seconds before you turn it off the next time and see if that makes a difference.

 

Shoulda just sold it when you had the chance

 

Chris you need a pair of horns and a tail in your avatar

Seriously, I have not paid attention till a few days ago. After having my appendix removed, I couln't drive for a couple of days. Wtching my GF start the car, I observed the puffs of smoke form the car's tailpipes. Which got me thinking I've seen that on quite a number of air-cooled Porsches.

 

Pistons in the 964 and 993 are called ported pistons.
Each piston has an oil sprayjet inside, that opens and sprays oil in the combustion chamber for cooling purposes.
Each sprayjet activates when oil pressure is at 3 bar and below (hot oil).
When engine is turned off for a 24 + hours, it could happen that one sprayjet let some oil in chamber resulting in a puff, absolutely normal according to porsche.
As of 01/1997, porsche bulletin asks their mechanics to change these sprayjets with bigger ones, see pdf attached.

A big discussion with porsche chief mechanic at zuffenhaussen about this process was essential to convince me I didn't need an engine rehab.
As per porsche technical sheets also, a HEALTHY 993 engine consumes normally 1 litre per 1000 kilometers in normal everyday driving.
Some on this forum think this is not normal, and claim their cars after an engine rebuilt, consume half a quart each 5-7 thousand miles. Do their sprayjets function?

 

To my humble knowledge, the oil is sprayed to the bottom of the piston, but not on the side of the combustion chamber, but opposite: inside of the piston. Imagine the oil being sprayed along/parallel to the connecting rod.

So oil drooles from the spray nozzle and wanders inside of the cylinder around the piston rings into the combustion chamber?

Best regards,

Felix

 

LOL, love ya, mean it.

 

The puff of oil is simply due to a small bit of oil leaking past the piston rings into the combustion chamber. This is a common trait of boxer engines. In all other engines, the oil simply drains down to the sump. But with horizontally opposed cylinders, oil can make its way past the piston rings when allowed to sit for a few days, let alone weeks. The oil is then burned off at startup, and is harmless to the engine (with this miniscule amount of oil, anyway), though does look unsettling and smells bad. The "fix" is to drive yer car daily!
Hope this helps.

Edward

 

Edward, I am actually driving my car daily and have done so for the past couple of years. True daily driver here with 133K miles.

Thanks everyone for assuring me that it's OK. I thought so too