1990 blue smoke when cold

J

jpschade

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Mar 7, 2012
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I have a 1990 w250 5 speed, I put new motor in over the summer that supposedly had 115k on it. original motor started knocking at about 500k. I used to get quite a bit of blue smoke with original motor on cold starts but I think newer motor smokes more. Only thing I swapped over from original motor was the ve and I have it rotated all the way to the head. No blow by, turbo is tight, downpipe is dry. It smokes bad on first start up and will start smoking if I let it sit for 5 minutes idling. Just noticed it tonight, if I hold it wot in 5th itll start chugging and doesn't feel like clutch is slipping. I have a high volume piston style lift pump coming for it anyway because current one is leaking, wondering if lift pump could be taking a sh!t . thanks
 
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Have you smelled it? Oil is pretty distinctive.

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Pull your downpipe off and look for oil in the pipe and turbine housing. If there is oil, pull the turbo and look for traces of oil in the manifold. If there is oil, pull the manifold and look to see which cylinders.

I would bank on valve seals or turbo seals. Blue smoke is oil related somewhere.
 
Do you have a spare set of injectors to swap? You're saying blue but the symptoms you listed sound like injectors.
 
I threw in a spare set but didn't make much of a difference. Pulled dp everything was dry
 
Some blue smoke on a cold diesel on start-up is pretty normal and not necessarily a sign of burning motor oil; fuel itself also can make blue smoke with low-enough temperatures, especially with lower compression.
 
Ram12vcummins said:
With bad rings the compression could be low also causing smoke and a raw fuel smell.
Click to expand...

Almost everything you do to hot-rod your engine makes cold start-up blue smoke worse than stock.

Low compression pistons? More blue smoke when it's cold outside.
Nice, big intercooler? More blue smoke when it's cold outside.
Big turbo? More blue smoke when it's cold outside.

Just tell yourself it's an indicator of more horsepower, not worn out piston rings. :nos:
 
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