Smoky exhaust - 986 Forum - The Community for Porsche Boxster & Cayman Owners

SherwoodForest · 11-20-2009, 08:31 AM

Greetings from a first-time poster. Just had to come here to make sure I'm doing the right thing. My 00 base Boxster wouldn't start for a couple of weeks while it sat in the garage. Lights, radio, windows all functioned (though the window drop-down function is totally screwed up). The car turned over, but not enough to start (even though I had it on a battery maintainer for the whole two weeks). So I finally got around to calling a Euro car repair shop (40 minute drive) and they advised a jump start attempt before having it flat bedded to the shop. So we jump started it last night. The startup sounded a bit funny for a couple of seconds (like something loose floating around, maybe) but after cranking it for a full minute or so, the car finally started and ran and seemed to settle into a slightly oscillating idle. Unfortunately, grey smoke poured from the exhaust. Too long to be normal, and it was constant, so I shut it off after a minute or so and restarted. Same result. Constant grey smoke. So I let it sit overnight and started it again this morning. Same grey smoke! Hmmm ... could this be the dreaded air oil separater thing I've heard about or something else? And I assume towing (expensive!) is preferable to the risk of driving. Advice? Thoughts? Arrgghhh!!!

mikefocke · 11-20-2009, 09:05 AM

The first thing to do is look inside the air intake tubing for signs of excessive oil. If the tube just short of the throttle body and after the intake from the AOS is covered in oil, you have an AOS diagnosis...and it is a messy Do It Yourself job but not rocket science.

But having sat for weeks, condensation in the exhaust can lead to grey smoke until the exhaust gets hot enough to burn out all that water (ever see a car driving along with water pouring out of the tailpipe?).

Look at the oil? Milky or normal oil look?

Look in the anti-freeze overflow/expansion-tank. Look normal?

So look at the intake and, if that seems ok and the fluids are ok, then warm it up and see if it goes away.

SherwoodForest · 11-20-2009, 10:30 AM

We'll give it a shot and thank you Mike! Do you think it would it be safe to drive the car around the neighborhood a bit or even 25 miles to the shop (assuming the oil looks normal--and I thought it did last night when I pulled the dipstick)?

stateofidleness · 11-20-2009, 01:23 PM

Bout 99% confident that it is the AOS (Air Oil Separator)
I had the exact same symptoms (minus the car sitting for a length of time)

The smoke for me (and there was a lot!) was only on cold starts and after about 4-5 minutes would subside to almost nothing (operating temp)

The AOS is around $150 plus 250-300 for install at indy shop. If you don't DIY, make sure they clean out the intake when they replace it so there is no oil residue left behind. Also, give it some run time at the shop when you pick it up to make sure they did not introduce any vacuum leaks.

Also, I didn't see you mention a CEL, but usually you will get a CEL with two codes (forgot what they are off the top of my head) but don't be surprised if one pops up after running it a bit.

tigrhwk · 11-22-2009, 04:24 PM

Original poster here replying from a different computer. After checking the dipstick again (all looked good) and messing around in the engine bay, I decided to take the car for a short drive. Four times around the neighborhood and the grey smoke disappeared. I also saw a trail of water in the driveway coming from the exhaust pipe when I left the garage. I was elated! No CEL codes so--fingers crossed--this is apparently not a AOS problem. However, I removed the big cold air tube connecting to the throttle body (not the little tube just off the throttle body) and for the life of me I cannot get it back into place. GAAA!!!! The throttle body connection has a ridge over which the plastic piece has to slip before you can tighten the clamp. Try as I might, I can't get the tube

over the ridge. I feel like an idiot! ANY SUGGESTIONS?

SherwoodForest · 11-23-2009, 05:56 AM

Bump: Now that an AOS problem has been ruled out, I'm dealing with a self-inflicted consequence: Does anyone have a suggestion on how to get the cold air intake tube (I ASSUME it's a cold air intake tube--it's the big black hollow plastic piece connecting to the throttle body) back onto the throttle body? I just can't seem to get it to slip into place. Is it a matter of brute force or is there a trick?

rob76turbo · 11-23-2009, 06:55 AM

Some people will cringe.... But I took a small pocket torch (the kind you light candle / grills with) and very gently took the flame around the edge of the intake tube. Maybe one minute total and just enough to get the plastic warm. Then it slid right on the intake. NOTE: be very careful and do NOT expose the flame to any oil, dirt or other residue or other engine component (the results would not be good). Make sure the tube is clean and free of any residue, oil, ETC. Do not attempt this if you feel that you could make a mistake. If done properly, the tube will slide right on the intake and as the plastic cools, will cool to its original shape.

Like I said some will cringe....but it has worked well for me.....

fastorange · 11-23-2009, 07:20 AM

That's a good idea, I recently installed Pedro's techno torque 2 and had the same difficulty reinstalling the intake tube to the t-body. I ended up using some light oil, a very small amount, on the tube and had to push very hard to get it to pop on. I could not believe the amount of force I had to use, and of course it isn't that easy to get your hand and arms in there....I used a large screwdriver as a lever to assist in getting enough force to get it to pop on.... I wish I would have thought of lightly heating it to get it to go on......

SherwoodForest · 11-23-2009, 08:41 AM

Wow. A pocket torch. Interesting idea and thank you! Maybe I'll try a hair dyer first!

SherwoodForest · 12-04-2009, 01:47 PM

OK, good news and something for others to consider if they're having trouble getting the stubborn black plastic cold air intake tube back onto the metal lip of the throttle body. After contemplating the blow torch concept mentioned by another poster, I opted for alternative heat in the form of a hair dryer. Seemed safer than applying an open flame and--wahoo!--the results were amazing. With a couple of minutes of heat applied around the lip of the plastic, the sucker slipped right back into place. This is actually easy to do if you just know this little trick--apply heat (and you can probably do so more safely with a hair dryer)!