irish guitar

I haven't driven my 2006 Carrera S for about a week or so. When I started it today I got a lot of smoke. I've never seen it do that before - I expect it from the GT3, but not from the S. Happy to say that subsequent start ups produced no smoke at all.

Car has 49,400 miles. I'm the original owner and the oil level is, and has been fine. Last oil change about 1000 miles ago.

Car has sat for much longer than this before. Has frequently been inactive for 6 weeks, plugged into battery maintainer with no prior issues.

Anyone care to speculate?

Vivian.

Tcc1999

I have an idea of why this happens but if I speculate in any detail I'll sound like an idiot. What I'm thinking is that oil will drain into a collection area when you last parked your car, then when you start it up again it will burn off. If you do an advanced search on Macster as the user and use a few keywords like smoke, start up, etc. you'll probably get several hits. His explanations are textbook! Concise, to the point and technical without being incomprehensible. Good luck.

EDIT:
I was curious so I went back and found the post I was thinking of. You should still do the search though as there is lots of other info.

Macster responded to a similar question:

"Probably normal. Techs tell me they see cars on the lot: new cars, used cars, even customer cars; smoke upon startup quite often.

The techs tell me that as long as the engine is not exhibiting any untoward behavior, the check engine light stays dark, and the smoking is short lived, tapering off and stopping almost as soon as it starts, the techs pay it no mind.

So should your friend.

To be thorough the car's vital fluids need to be checked. If the coolant level is dropping and the oil level is rising this can be intermix problem, which is serious. It is also quite rare. But the car is still almost new with just 20K miles. It is miles that bring on the issues, not time.

Couple of things your friend can do. Be sure the engine is not overfilled with oil. Be sure the oil does not have too many short trips on it. This can contaminate the oil with unburned fuel and water (combustion by products) and this dilutes the oil and makes it more prone to foaming which adds oil vapor to the crankcase which the AOS (air/oil separator) is not up to removing and it is this oil vapor that causes the smoking.

The oil vapor passes through the sub-par AOS and the vapor has to make a sharp turn at the intake. The droplets in the vapor continue straight and impact on the intake manifold wall. When the engine is shut down and if there is any oil on the wall -- techs tell me that almost always when the intake is opened up they spot the intake walls are wet with oil -- as the hot engine sits the intake warms up from the heat of the engine and the oil runs down and onto intake valves or past open valves into the combustion chamber where the next time the cold engine is started the oil burns incompletely -- cold engine -- and passes through non-functioning converters -- cold converters -- and the smoke is what results.

So again the smoking is (probably) normal but advise your friend to check vital fluids and if the oil has some miles on it and gets used for short trips -- which it probably does -- consider an oil/filter service now and on a more frequent schedule going forward. "

ADias

If the smoke was white is probably water vapor; normal in wet winter days.

StormRune

I've seen it on occasion, especially if the car is parked or an angle tilted to one side or the other. I have read that it is not unusual for a flat 6 since the cylinders are sitting sideways and when parked it is possible for a little oil to seep past the gaps in the rings on the downhill side if they happen to be oriented so the gap is at the bottom.
I wouldn't worry unless it became a regular thing.

Wayne Smith

+ 1. I've read the same thing.

Comanche_699

I just call it THE DRAGON SMOKE.

I love it. Sadly the little grey frog rarely sits for long enough to get the oil seepage and lusty black plumes on start up, but I quite enjoy seeing them on occasions they present themselves.

I would say absolutely nothing to worry about. Your car is just a beast. Now and again it likes to belch a little smoke; That's understandable considering it also drinks gas, breathes fire, screams through tunnels, and literally flies over the open road.

That's how dragons do.

Wayne Smith

Where's the LIKE button? Well stated!

StormRune

There is one more contributing factor that I just recalled after seeing Comanche's excellent "beast" comments.

Since our engines are designed to withstand prolonged track conditions, the pistons fit more loosely in the cylinders than virtually any other car made. This allows them to fit properly when expanded by very high heat loads under racing conditions. This is also why it is undesirable to over-rev our engines when completely cold... the pistons are still relatively loose in the cylinders. Due to this looseness and the previously mentioned effect of the cylinders laying sideways and gravity-driven pooling of the oil, it is easier for oil to leak past the pistons and rings when sitting idle. I would guess that very cold weather makes this even worse since the pistons would fit even more loosely.

Macster

No these engines are not designed for the track. They are designed with the requirements arising from street use, and all the rules and regulations fully in mind regarding fuel economy and emissions and for driver comfort regarding absence of noise vibration and harshess, everything that goes into making an engine suitable for use on the street and capable of satisfying the overwhelming majority of customers.

Thus the pistons are not fitted with more clearance.

In fact, street engines run with quite often very tight clearances as this makes for a quiet and fuel efficient and clean running engine.

You'd hear a ton of piston slap until the pistons were at the full operating temperature. (Just ask the Corvette owners who back in the early 2000's were fussing about hearing piston slap when Chevy brought out Corvette engines with too much piston/cylinder clearance.)

Piston temperature even at high engine loads and speeds is very well controlled by a each cylinder having an oil jet which directs a substantial amount of oil at the underside of the piston. Word is this oil jet cuts piston temperature by 50C.

Far and away the bulk of the oil that causes the initial start up smoking comes from oil that makes it to the intake past/through an inefficient AOS.

As long as the car is parked on flat ground or at least with the car pointed up or down slope while there is some oil in the cylinders -- courtesy of the oil jets -- it will not flow past the rings/pistons into the combustion chamber. The chambers are hot as is the piston top and this heat actually works to cause the oil to flow the other direction.

Now if the car is parked on a side slope -- I never park my car this way for anything but just a few minutes occasionally when I visit the post office and park on the side of a street that dips quite a bit down on the right side -- gravity could cause the oil once things are cold to possibly seep into the combustion chamber past the rings/piston. However, these clearances are quite small and while I can't say for sure I do not feel even in this case this accounts for any significant amount of oil getting into the combustion chambers.

If you park your car in such a manner and the engine smokes often upon cold start then try to park the car more level and see if that make a difference. If it does then at least you know what to do to avoid smoking at cold start.

StormRune

"Thus the pistons are not fitted with more clearance"

Sorry Macster, but I'm afraid you are a wrong for a change. That claim wasn't my own but was published in a report by the Porsche experts at Hartech.

And yes, these cars are made to be both legally and practically streetable while at the same time they are designed to hold up much better than most common engines on the track. They are designed to be trackable.

Hartech has a set of reports at http://hartech.org/porsche_996_997_B...ers_guide.html. In the one at the last link (a 72 page beauty!) they talk about this. If you aren't up to reading the whole thing, take a look at the Supplement section they start on page 57 where this is specifically discussed.

irish guitar

Thanks for all the replies.

FYI, the car is always parked level in the garage.

Vivian.

irish guitar

Tardy follow up:

Turned out to be the oil separator. Replaced at dealer, no further problems.

Vivian

vern1

Ah ha that will do it.

Mine smokes on occasion (nasty habit that) and I find if I let it idle for 30-45 secs before I shut it off that it doesn't normally smoke upon restart the next day

irish guitar

No, this was way beyond that. We can expect some smoke on start up from these cars - especially during cold weather, but this was about 5 times what my RS puts out at it's worst. Furthermore, it was happening with every cold start.

Water pump. Oil separator. There are just certain components that have a short lifespan on the 997.

Vivian