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Thread: FIXED? Help diagnose my smoking issue... FIXED?

  1. #1
    Join Date
    Mar 2006
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    FIXED? Help diagnose my smoking issue... FIXED?

    OK here's the deal.

    When the turbo was being rebuilt, the builder called and said the oil inlet fitting on the turbo was plugged with debris and that contributed to the bearing failure.

    When I got the turbo back and installed, it started smoking out the exhaust after driving for a while. I called the builder, talked to a couple of guys on here, and was told to put a nitrous jet in-line to restrict the oil flow to the turbo. Did that, still smoked. Went with a smaller jet, still smoked. Put an in-line filter in, still smoked.

    This past weekend I replaced the drivers side head. Reason being is there was oil on my front plug. A couple of weeks ago, we found a bad valve seal and replaced that hoping it was the problem. Still smoked.

    Typically, the best I can tell, it would only smoke at idle. Today on the way home traffic was at a crawl on the freeway and even driving at slow speeds (10-15?) it was smoking bad. We're talking plumes of blue smoke rolling out from under the truck.

    So I get home, and am racking my brain trying to figure out what it could be. I thought maybe the oil drain was plugged. Take it off the turbo side, blow through it, hit resistance, then it clears all the sudden. I think to myself that may have solved my problem. Call the builder, he says it might be. Drive it around, smokes a little, stops but the starts later on just as bad as usual.


    Possible causes:

    1.) My drain comes off the front of the oil pan off a straight nipple. It then dips about 3" or 4" to go under the crank pulley, and then goes back up and to the turbo. The builder today said that dip may be trapping air, forcing the oil back into the turbo and making it blow by somehow and into the exhaust. So at some point, I'm going to put a 90 degree elbow off the oil pan so the hose runs continuously "uphill" with no dips.

    2.) A bad valve stem seal on the passengers side?

    3.) According to the builder, there is a piston and ring (similar to the piston and ring in an engine) in the turbo and is the only likely place for the oil to blow-by. He said the chances of the ring being bad is extremely slim. But I guess it's an option.

    4.) I'm going to pull the downpipe at some point to see if the oil is truly coming out of the turbo. Or I may pull the crosspipe to see if it's coming out either the exhaust or turbo manifold.


    Any other ideas?

  2. #2
    Join Date
    Nov 2003
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    Your oil MUST run downhill. If it runs uphill it will settle in the hose, pooling, and then the oil on top of it has to push its way through. Whatever you do, make sure the oil has a continuous gravity feed to the oil pan.
    See my truck data in the "My Garage" section here... http://www.ls1truck.com/forums/my-ga...tml#post191709

  3. #3
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    ok. That's next on my agenda is to rectify the dip in the line (or maybe I'm the dip that needs help...?)

  4. #4
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    Do not restrict the turbo feed line unless its a ball bearing turbo, a -3 to -4 oil feed is perfect. You'll kill a journal bearing turbo with a restrictor in there. I would say that the drain is causing the issue IMO, I cant see it being a valve seal (it wont generally smoke ALOT i if it is one, mainly on startup). The oil drain must be a -10 (-12 preferred) and run a constant downhill slope from the turbo with as little restrictions as possible. I'm sure you know this all already but just stating it for the heck of it

  5. #5
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    Quote Originally Posted by Justin_Inc View Post
    Do not restrict the turbo feed line unless its a ball bearing turbo, a -3 to -4 oil feed is perfect. You'll kill a journal bearing turbo with a restrictor in there. I would say that the drain is causing the issue IMO, I cant see it being a valve seal (it wont generally smoke ALOT i if it is one, mainly on startup). The oil drain must be a -10 (-12 preferred) and run a constant downhill slope from the turbo with as little restrictions as possible. I'm sure you know this all already but just stating it for the heck of it

    He has a ball bearing turbo and 5/8'' drain line
    2006 silverado SS....Clifford Jr...turbo coming soon
    1970 Chevelle ly6 swap....d1 coming soon

  6. #6
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    Quote Originally Posted by RedHeartbeat View Post
    Your oil MUST run downhill. If it runs uphill it will settle in the hose, pooling, and then the oil on top of it has to push its way through. Whatever you do, make sure the oil has a continuous gravity feed to the oil pan.
    +1 on getting that fixed.

    Wouldn't be an issue if it was pumped, but since it is gravity, it doesn't take much to slow the drain since you only have like what, 2'-3' of head pressure on a 5/8" line? Not much force there.
    Gone, but not forgotten!

  7. #7
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    OK, so I got the drain re-done. Had to remove the intercooler, remove the old drain line (which had a bunch of oil in it), remove the thread-to-barb nipple, and installed a thread x thread 3/8" elbow. Not much room to work, but got it in there. Clamped on some clear line so I can see what it's doing (draining, filling, etc.). Going to take it for a test drive in the morning to see if it smokes at all or if it cured the problem.

    I did start it up just to see what it would do, and it drained fine. The last picture is with the truck running and the oil draining. Not sure how long it will stay clear, but I like being able to see if it's draining or not.








  8. #8
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    The smaller things you knock out like that, the easier this will be to diagnose. But you just gave me an idea to replace all my rubber hoses with see through hoses. How cool would that be?
    1951 3100
    1984 C10

  9. #9
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    Good luck moze...Ive never seen any see through hoses that will hold up to oil/heat....

  10. #10
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    Quote Originally Posted by DBRODS View Post
    Good luck moze...Ive never seen any see through hoses that will hold up to oil/heat....
    Thanks Jon. It's for testing if nothing else. I bought 5' of the clear and 5' of actual heater hose. The clear is good for 300 degrees according to the display at the store. I just wanted to see what was going on with it. If I have to replace it, at least I'll know by then whether the drain was my problem or not.

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