03996

But I did at least search for this but didn't see anything that talked to my specific problem................

C4S - Car sits unused typically for about a week (yes I know, use the bloody thing!) and so when I start it up I get blue smoke. Not a lot and nothing like some of the video clips I saw during my search on this forum but enough to say hmmmmm.

Typically when I do drive it it's to meet with a bunch of guys at the local coffee shop, about 20 miles away. Sit around for about 2 hrs, start it up, no smoke that I can see from the drivers seat. Uses very little if any oil. Has 0/40 Mobil1 in it.

If this was a "normal" car I'd say I have worn seals and/or valve guides, but this isn't a normal car and I've read that this stuff is kinda "normal" for these cars.

Car has about 97k on it and I've owned it for the last 22k miles. Has been doing this for almost all of that times but it just seems a little worse now.

AOS was replaced by dealer about 15k ago, along with Flat6 RMS bearing, clutch kit, rear main seal,

So, is this "normal" or is this a sign of bad things to come??

Appreciate the insights and advice! Oh, and apologies for boring you folks with this.

AWDGuy

if you Google the problem, you will read threads of guys in their 991's experiencing this issue. that's upsetting considering those are new cars.

people chalk it up to the flat 6 design. some do it, some don't. from what I've read it is more common with cars that sit.

make sure the oil isn't overfilled.

03996

Wow, a search on Google, as you suggested, seems to indicate almost ALL of the flat 6 engines do this at one time or another when starting from cold!!

As far as overfilling the oil goes.......my electronic oil level indicator shows readings all over the place, from over the top to three sections low. Consequently I now only use the dip stick, and that shows full.

Thanks for your reply.

wildbilly32

Full to the top line or full to the dot? I've read the dot is overfull. Some/many suggest keep it at 1/2 stick...and yes mine occasionally smokes on start after sitting in garage for days. I've read let car idle when parking for a short time, especially if you were leaning on the throttle prior. Guess this gives the AOS the opportunity to catch-up with the oil vapors.

AWDGuy

if the dip stick shows full, you might be slightly overfilled. it will smoke on every cold start up in this case.

extanker

sometimes hot
sometimes cold
sometimes alot
sometimes not
they do it but here is a short list on stopping it from the experts [BTW NONE WORK BUT THEY ARE FUNNY] let it idle for 23.7 seconds before shutting off,park on 7 degree angle [i swear i have read here some park it nose up/some nose down] run it a quart low on oil or 231.2 mls. low ,do not use mobile 1 etc

Macster

Normal.

All I can offer is what the techs have told me regarding this smoking (and bolstered by my own experience). If at engine start the engine smokes and if the smoking is short lived, stops or begins to taper off almost as soon as it starts, is *not* accompanied any untoward engine behavior and the CEL remains dark it is nothing.

More than likely the smoking is a bit of oil in the intake courtesy of an inefficient AOS. The techs tell me almost to a car whenever they have to expose the intake the intake is wet with oil which is oil that comes from the oil vapor the AOS lets pass through.

My own experience is the engine is most likely to smoke if used for a short trip or if I come in kind of "hot" and proceed to rev the engine a bit higher than usual just before shutting it off.

For example, after my usual 30 mile drive from work to home the last stop sign is just a hundred or so feet from my driveway. I accelerate from the stop sign in 1st (naturally) and sometimes I let the engine RPMs climb to 4K or so then slow and turn into the drive and park the car. Sometimes I let the engine idile -- if say the radiator fans or engine compartment fan is running -- but at other times I just shut off the engine a moment or two after pulling into the parking space.

In the above case sometimes -- not often but once in a while -- the engine will smoke upon the next cold start (the next morning).

Now if I don't rev the engine as high after leaving the stop sign, say limit the RPMs to 3K, if the rest of the parking operation and engine shut down is the same, and it is, the engine is less likely to smoke up the next cold start.

Regardless though I have found over the years as the oil closes in on accumulating 5K miles the engine is more likely to smoke upon cold start. The smoking is not that much more frequent but I can go a long long time with the engine not smoking and then one morning after starting the engine notice a cloud of smoke wafting over the car and then look down at the dash and note the mileage is closing in on 5K miles since the last oil/filter service.

So relax and follow some common sense things. Don't overfill the engine with oil. I am not a fan of running the oll level purposely low. I run the oil level in both of my car engines at the max line -- when measured hot -- and add oil when the leve drops enough that a quart is required to bring the level back up to the max line again.

Do not run the oil too long. In your usage a 20 mile drive may not get the engine (the engine oil at least) fully up to temperature. The oil needs to get hot and remain hot in order to boil out any water it has accumulated.

In your case I suspect the oil is getting a bit more contaminated due to the "short" trips and this increases its propensity to foam and generate oil vapor which just increases the odds of the engine smoking upon next cold engine start.

As I touched upon above I run the oil 5K miles and at close to 5K miles the smoking at cold start is more likely. Since my usage is pretty consistent day in and day I attribute this to the oil becoming degraded (contaminated).

Balu

Piston ring orientation in a horizontal cylinder
at rest perhaps acerbated by all the above?

ejdoherty911

When you're in 3rd gear and the rpm is up around 4,500 and you slam on the accelerator, does it feel good? If the answer is yes, your car is fine. Mine smokes too on occasion.

03996

Thank you Macster, and thanks to all for replying!

Answer to the question......3rd gear, slam it, does it feel good.......absolutely it does and it's the reason I look for opportunities to do just that........probably makes me look like an a-hole to some drivers.....oh well.

I think my car is fine! Thanks again.

mlee2122

great info... very helpful thread.

03996

Just a quick update......I followed the suggestion of letting the car idle for a short while following a decent drive. I let it idle for around 30+ seconds I guess. Tried this about 5 times so far and.......no smoke or startup, hot or cold, or at least none that I can see out of the mirros which is how I'd been observing it.

So, clearly there's something to this extended idling.......hope I haven't spoken to soon!

Thanks again to all those that provided advice.

Palting

Glad you were reassured.

Here's one more theory on the 996 blue smoke: It's the oil/air separator. Driven hard with oil up to the full mark, then shut the engine down, there is residual oil in there. Start it up, poof, a large blue cloud just appears out of nowhere from the residual oil in the separator. Usually happens to me at the track. Don't drive hard, no smoke. Or, drive gently around the parking area after a hard run at the track. This clears the separator, no smoke on startup. Works for me. Others say only fill oil halfway, or idle the engine for a few minutes, but I am a fan of neither for obvious reasons.

ejdoherty911

Smoke at start up significantly reduced (almost completely gone) after replacing the oil filler tube.

I used to experience white smoke at start up, never lasted too long but it was there. Some days quite a bit of smoke for 30 seconds or so. I just accepted it as part of owning a car with over 100k miles on it.

...and then I replaced my oil filler tube which had cracked in half due to aging brittle plastic. I didn't expect any reduction in tailpipe smoke since I assumed it was due to an aging engine, but apparently replacing the oil filler tube helped significantly. The tailpipe smoke was reduced to just a little bit at start up for just a few seconds. Night and day difference, don't know why. I had not come across any prior reference to cracked or failing oil filler tubes being the culprit of tailpipe smoke, and I'm not certain that is/was the cause, but I do know immediately after replacing the oil filler tube the issue was almost resolved completely.

Jnelso

After a run on the track at a DE event I have a strong odor of burning oil but no sign of oil leak. Normal every day driving I dont get that burning oil smell. I think I read that someone suggested running with slightly lower oil level. I dont have a blue smoke issue. Anyone experince this?