Hi guys I've noticed that recently on cold starts I give get a plume of thick black smoke which can be alarming at times. This does not occur after every start and usually stops after a min or two or when I start driving. When I accelerate hard I see this smoke at times as well. I think it may be oil burning but why is it intermittent? Do I have anything to worry about?
Thanks for any advice.

 

HI,Black smoke is usually a sign of an overly rich fuel mixture..
Usually oil is whitish blue or very ligth blue color..
Look down your tail pipes with a flash light to see what tint/shade of black they are...Oil is a very shinny wet looking black
Good Luck

 

First some info:
White smoke: White smoke is caused by coolant entering the cylinder, and the engine trying to burn it with the fuel. The white smoke is steam. Blue Smoke: Blue smoke is caused by oil entering the cylinder area and being burned along with the fuel air mixture. Black Smoke: Black smoke is caused by fuel that has entered the cylinder area and cannot be burned completely. My guess is your smoke is blue?

Second, what you describe sounds quite normal. It is intermittent as what the oil does when you shut down can vary (it is normal to have some remnant oil sitting in the cylinders) Third, make sure you are cooling the turbos...regardless of how far or how hard you run them (if they engage at all). Realize they are cooled almost entirely by the oil that runs through them. The second you shut your car down...the oil flow stops. Look at the turbos after a short ride...now touch them...they are hot. Just let them cool 90-120 seconds, always (even when you stop for gas).

 

MORE INFO
Blue smoke or whitish blue smoke,oil, can also come from exhaust guides or exhaust seals leaking which will never be burnt in the combustion chamber or show on the spark plugs..

 

So should I be checking the exhaust seals or the cylinder heads?

 

I dont think that would be your problem, I just mentioned that to be informed of another cause of oil smoke also..
I would check your tail pipes out like I said above to determine if you see oil residue..But you say it is black smoke which doesnt sound like oil.
Sometimes many of the 996 Turbos puff whitish blue smoke once in awhile on start ups.

 

So I checked my tail pipes and there is no oilish residue. I paid more attention and the smoke appears more whitish with some blue tinge and a smell of oil. This comes on most times when I start and also at times when I downshift into a corner before acceleration. It also happened when I downshifted to a stop at the red light.
Spoke to a mechanic who thinks it may be turbo seals leaking and that the turbos may need replacement. Another told me it was the engine gaskets. He also suggested that my oil may have been overfilled as I just did a service.
Appreciate any thoughts.

 

Well the smoke at startup is not unusual as I already indicated...most likely due to oil in the cylinders at shut down. The smoke during driving is a concern...Did you check your oil level? What oil did you put in? Could well be a seal.

 

Oil level at full bars. Using mobil 1 0W 40. Not sure why if it's a seal it only happens intermittently.

 

Depending on where your throttle is on the down shift may cause a high vacuum situation which 'could' cause oil to be sucked from some where like a seal..
I would be more worried if it happened under acceleration,thats my opinion..
But also I dont know how bad we are talkng here as far as seeing smoke??
Does it make a difference when the oil is cold,thicker, as compared to when it is hot ,thinner?
I would try 5W40 or maybe 10W40 and keep an eye on your oil consumption also..
Just my info to help here,good luck..