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90 740T smokes

Hi all,

My 90 740 turbo intercooler has begun showing Blue/white smoke when engine is warm. (the needle is in the middle of temp gauge) I looked at the dip stick, after a while, and the level didn't decrease, so the car doesn't consume extra oil, that's my problem. ALso, I Replaced Turbo 1000 km ago . ( 285 000 km total) Have been faithful about changing oil. Compression is excellent all four cylinders ( around 130 psi each). Engine never overheated. Impeller turns freely. No unusual noises when running. Slight amount of oil or prestone in intlet side of piping. There is also some oil that is leaking in my intercooler, i removed the

screw under and it gave me around 2-3 ml of black oil. (old oil because a made a oil change) Also, my fuel tank decrease rapidly.

So, if someone can help me or have any idea of the source of the problem

Any help, ideas anyone could offer would be appreciated. Reply here or

email me at louis snipped-for-privacy@hotmail.com. Thanks

Reply to
Louis
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My first thought is for the crankcase pressure building up. Most often that shows up first at idle, causing billows of blue smoke when idling and for about 30 seconds after taking off. When the crankcase pressure builds up the oil backs up into the turbo and dribbles into the exhaust.

Remove the oil filler cap, then unfasten the hose that crosses over the top of the engine from where it attaches to the side of the turbo intake duct and try blowing through it. The resistance should be a bit more than you would expect of the hose itself but not as much as if you were trying to blow through a soda straw. You should be able to exhale in three seconds or so. If it does not flow freely, check the hose pieces (no fooling!) and the oil/air separator box it attaches to under the intake manifold. That box is held by two bolts and the friction of the two o-rings beneath it. If the box is plugged it can be cleaned, but not well and not easily. Replacement is a better alternative if available.

Mike

Reply to
Michael Pardee

I forgot to mention - that oil pervading the intake system is normal for the

740/760/940 turbos. The crankcase ventilation system sucks the mist out of the crankcase and reintroduces it ahead of the turbo. It collects in the intercooler and coats all the ducts.

Mike

Reply to
Michael Pardee

Interesting, this raises a question for me (please be forgiving I am green)

So if a person switches to synthetic oil is there anything ahead here in the intercooler which might not be synthetic friendly?

Reply to
KLB

I hadn't thought about that when I switched to synthetic

Reply to
Michael Pardee

i looked at the crankcase hose, and they appear to be pretty good, no oil residue or else. I blew some air in it as well and it didn't seem to have much restriction.

Also, I have a small prestone leak, I don't know if it matters. Else, after my engine runs for a while. once stopped I remove the oil filler cap, and some little white smoke out of it. I can't say if it's normal or not.

DO you have any other idea, or should i change oil to synthetic???

Thx Louis

Reply to
Louis

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