iipod

JAGMAN1

iipod

Balr14

Mine spit out quite a lot of watery black soot when I first got it. It has aftermarket headers and exhaust and had not been driven much in 6 months. I had the AOS replaced (just in case) and drove it several days a week. It stopped doing that after about a month, I think. It might have been a lot sooner, but I was never concerned about it so I didn't really pay attention to when it stopped.

cosm3os

I'm guessing by the condition of the tips (unless they are originally matte black), it's sooty water.

Iceter

Most likely dirty water. You most often see this on start up when water has had time to condense in the exhaust. It shouldn't happen after the car warms up.

Its unlikely that it is oil. The exhaust gets too hot for oil to make it all the way back to the tips. It would burn off well before that, and if you had oil spewing out of your exhaust, you'd have other, more obvious signs of disaster.

SweetWater

Watery soot. I get the same from mine.

Dennis R. Cliff

I am sorry but the presence of soot does not sound good. My 997.2 had thick sooty exhaust tips when I purchased it and I found the cause to be overfilling of oil by about eighteen ounces. I did a borescope of all six cylinders and saw an occasional thin streak of oil on the cylinder walls which came from oil being forced between the ring gaps. After removing the 18 ounces from the engine I cleaned the exhaust tips and now after 500 miles there are no deposits on the tips. The engine management functions in these cars keep the air-fuel ratio optimum so if you are getting soot it can only be coming from burned oil. If your oil level (checked on a flat garage surface) is good then you have to wonder about bore scoring. You can get a good borescope on Ebay for about $109.00 and they are pretty easy to use once you remove the spark plugs. If the engine is not properly warmed up per short trips you will get the condensation spitting out of the tips with the carbon. Good luck and let us know what you find.

JAGMAN1

Balr14

In case my oil had been over-filled, I replaced the AOS. A borescope doesn't reach the bottom of the cylinder, so it doesn't do much good in the 997.2 engine.

Tcc1999

iipod

Balr14

That is pretty normal with aftermarket exhaust. DFI engines blow a lot of crap out when you start cold.

Iceter

Do both sides get sooty equally or does the left get black much faster?

Dennis R. Cliff

I think that Porsche states that the DFI engines do burn some oil and that a certain number of miles per quart is to be expected but your soot deposits over short driving time suggest that your car is burning more oil than what would be normal. Have you checked your oil level to rule out over filling? My same model Porsche has 54K miles on it and the rubbing of fingers around inside both exhaust tips results in zero soot in the fingers. It seems that excessive oil burning can come from two sources. A well worn engine with oil making it's way past valve guides and piston rings or the presence scored bores. It would seem unlikely that a 40K engine would be worn enough to produce so much soot. I also disagree with the above statement that you cannot get good info from bore scoping a DFI engine. If the piston skirts do not rise high enough in the cylinders to leave scoring visible at BDC then you would have combustion chamber volumes measured in fluid ounces and not cubic centimeters. One of the posts on the forum states that after market exhausts will cause more soot deposits for some reason. My Porsche has Fister mufflers and Sharkworks cross over pipes. Also, the less restriction that you have in an exhaust system the leaner that an engine will run. If soot is building up on the actual bumper bodywork of the car it could come from exhaust gases leaking from the crossover pipe to muffler joint. If it were my car and the oil level was OK, I would definitely get at least the #2 cylinder bank scoped.