993 Faq Frequently Asked Questions about the Porsche 1994-1997 993

07/22/2003

Smoking exhaust on startup ( TT cars )

Filed under: Engine,Turbo — Jeff 993TT @ 11:07 pm

If your car starts smoking upon startup and DOES NOT go away after a seconds, you make have a different problem.

Usually, smoke starts pouring out of the left side ( driver’s side ) exhaust. White billowly clouds behind your exotic sports car. Not a good sight.

Most owners notice this after an oil change which included changing the oil filters.

Here are the symptoms:

a) Smoking on left side tailpipe ( driver’s side )

b) Small drips of oil under the right turbo ( passenger side )

c) Excessive oil in the turbo intake pipes

d) Excessive oil in the intercooler ( there should just be a very light film of oil in there. )

e) No other driveability problems, ie getting full 0.8 bar boost, etc.

f) Strong oil smell when the car is idleing or turned off after running it.

Usually, smoke in one side of the exhaust points to points to a bad turbo seal. These seals are like piston seals and DO NOT degrade over time. The normal lifespan for turbos ( which have NOT been abused or hot shutdown’d ) is about 75K miles. If you have a low mileage TT, I would not suspect faulty turbos just yet.

Here are the diagnostic procedures:

a) Drain both turbo oil tanks. You should get the same amount of oil in each. If they are drastically different, then you may have a bad turbo seal. If they are pretty much the same, then you should keep looking. Your turbos are probably fine.

b) Do another oil change. But this time, verify, I mean VERIFY that the engine oil filer ( the small one ) part number ends in 03. There was a TSB about older filters not working properly. There is a check valve in the filter which is VERY sensitive to how tightly the filter is screwed on. Follow the service manuals which state to HAND TIGHTEN, then do another full turn with the wrench. If you don’t tighten it sufficiently, then the check valve will not make contact to the engine nipple.

c) Do not overfill the engine. Fill it to the lowest twisted mark on the dipstick.

d) Use 15w50 Mobil1 oil. I can’t confirm that this really does anything, but the two times I’ve used 0w40, my smoking returned.

e) Clean out your turbo intake hoses and intercooler for any residual oil. Even if you fix the problem by using the correct oil filter or tightening it correctly, you will still see smoke if there is oil in these 2 areas.

Following these procedures, I’m smoke free. Even the smoke puff on startup is gone. However, usually, after I do another oil change, I will get smoking/oil drips again. I can never seem to get the oil level just right and habitually overfill it. DOH. The oil level is VERY SENSITIVE, DO NOT OVERFILL!

I’ve helped over 15+ TT owners fix their smoking problems with these procedures. If you’ve done all these and you still have problems and can confirm that your turbo are still good ( via the oil level of the turbo oil tanks ), then there is another solution.

Andial in Santa Ana, CA ( southern California ) sells modified turbo oil lines to prevent the oil from collecting in the turbo. They are specially modified and bent oil lines which replace the current ones.

You may be asking why is the problem happening in the first place? It appears that the turbos are lower than the crankcase. So gravity will pull the oil down and it will pool in the turbos. That is why the system of check valves is so important. That is also why using the Andial solution should work too. It just raises the oil line so that gravity will not automatically drain the oil from the crankcase to the turbo. In the 996 turbos, they have check valves in the oil lines to address this issue. Not sure why they did not design the 993 the same way.

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