Hi guys, I rebuilt my turbo properly this time and all is well but it still smokes bad out the tail pipe only on the first 5 minutes of driving. Once the engine gets cold and I restart it, I have these smoking issues again, but not when its all warmed up.

Crankcase ventilation is perfect, no vaccum leaks because I replaced all that. Oil level is actually lower than usual just to cancel out the overfill theory.

Somehow oil is still hanging up in the turbo Im guessing and I dont understand it because all the lines are clean and it only smokes on initial start up.

Any ideas???

Thank you!!

Is it clouds of smoke or just whiffs?

Did it smoke before the turbo rebuild?

Has it been driven enough to really clean it out? How many miles?

Did the new turbo seal go in OK? My TD05 has 2 grooves.(carbon dam?)

Was the seal bore clean and smooth?

Was all the coked oil cleaned away from the seal area on the inside of the center section. You have work through the drainback hole with a dull tool. Or when the center section is open on the compressor side.

Does the compressor bypass valve (CBV) hold vacuum? If not, the diaphragm inside might be perforated and allowing oil to be drawn into the intake at idle, when manifold vacuum is high. I have had this problem in the past on my '92 945T, and it smoked so badly it was hard to see behind me for a block or two!

The diaphragms are available in aftermarket from some guy in Taiwan on e-bay-- $40USD instead of $165 from US sources.

Good luck!

Do you have contact info for these CBVs? I did a MacGiver on mine (Mitsubishi TD05-13C I believe), and would like to replace it with a proper unit, but couldn't find one for a reasonable price.

--
David Armstrong - '86 240(350k km?), '93 940T(270k km), '89 240(parts source for others) near Toronto

Hi David:

Mine is being held together (more or less) by a thin smear of RTV, so I need to get one too.

Here's the e-bay number:

260074371702

I seem to recall T&D wanting $161 USD for one...

If you decide you want one we could get together and order two to save some shipping and duties. Let me know!

If the compressor bypass valve is shot, would it stop smoking at idle once the car is all warmed up? My car only smokes on initial warm up and driving for the first five minutes. I also don't have any oil in my intercooler.

You can run without the CBV as I did for 300,000+ mi.without problems. It is spring loaded and no boost will be lost if disconnected, just plug off the vacuum supply.

The vacuum hose should connect directly to the intake manifold, I can't imagine there would be that much oil vapor in the manifold?

Was it doing the same thing before the turbo was rebuilt? How many miles on the engine? What's the compression like?

Was it doing the same thing before the turbo was rebuilt? How many miles on the engine? What's the compression like?

HI!

I don`t know what type is it, oil or water cooled, Garret or Mitsubishi or..? How did you rebuild it, how bad was original, what is the engines condition? Does it make smoke when you push the pedal or when you loose it? Only when engine is cold?
What kind of oil do you use? Is there been chances in boost pressure,what is it? Sorry i just ask many questions, I try answer too, when I know all the specs.

YRS:WEBERMAN

That sounds like bad rings.....

-Will
--
1990 740 Turbo, on its way to stock specs, maybe beyond

Can you have bad rings while having good compression with nice clean spark plugs? If you have bad rings, will you have oil in the exhaust manifold? When I took off the turbo it was nice and clean where the exhaust manifold is. The turbo is a TD04H-13c on a 1990 760, it didnt seem too bad when I rebuilt it, just a little coked up, however the last piston ring disintegrated when I pulled the shaft out, it was replaced properly with a new piston ring type seal as everything else was replaced inside and a good thorough cleaning prior.

Bad rings makes for pressure build up in the crankcase, right?

If it were bad rings, wouldnt it smoke non stop? Im using 20w-50 oil as suggested by my Volvo mechanic.

Any other ideas?

You'll find a range of opinions about oil, but I believe most turbo people will recommend a much lighter oil than 20w50. A Volvo indie mechanic I knew liked heavy oil - because it quieted down the piston slap on B230s and made his customers happy. It's not necessarily the best thing for the engine though, particularly the turbo. Not sure if this is contributing to your problem though...
--
Chris, Dartmouth NS Canada 70 M-B 280SE, 83 245DL, 84 244 turbo, 90 780 turbo, 92 VW Golf, 90 740 Rex/Regina