Blown turbo symptoms?

Discussion in 'Technical' started by Cliff, Feb 12, 2019.

  1. Cliff

    Cliff Member

    My car is producing blue smoke from the exhaust under these conditions; either:

    1. Once the accelerator is touched after engine braking (coasting without using the clutch or neutral).

    2. On extreme engine braking (as if preparing to come to a complete stop).

    Here is a video that shows me coasting and then using the throttle. The end of the video shows me hard engine braking (2nd gear) and the effects of such.

    It only happens under vacuum (-12psi or stronger) and not really when boosting.

    Only a small amount of smoke on startup (forged pistons in 30° F weather), but goes away once engine is at temperature.

    No smoke at stop lights (unless engine braking is used). Throwing the car in neutral before slowing down prevents smoking.

    My searching around most point to blown turbo seals or leaky valve stem seals. But I just replaced the valve stem seals 6 months ago.

    So here are my questions:

    In any case (valve seals or turbo seals) how likely is it for both sides to start smoking at the same time (granted the right side is considerably worse)?

    If it were turbo seals, wouldn't I see oil dropping from the turbos? Mine are dry.

    Screenshot_20190211-104116_Gallery.jpg Screenshot_20190211-104132_Gallery.jpg

    If it were turbo seals, wouldn't there be oil in my intercoolers? Mine are dry.

    If it were the valve seals, wouldnt that affect my compression numbers? Mine are the same as they were 6 months ago; cylinder:

    1. 145
    2. 140
    3. 140
    4. 140
    5. 142
    6. 140

    The thing that really throws me off is that this all started happening after I changed and bled my brakes :eek:o_O

    Any insights as the what and where to start looking or diagnosing are greatly appreciated :(
  2. beaver

    beaver southern zeds

    Check the inlet side pipes of the intercoolers, that is where you'll find oil if a turbo seal is leaking oil into the compressor side of things, the other intercoolers pipes usually only have a light film of oil showing. Valve stem seals usually leak oil into the chambers after the car has been shut down over night and smoke at start up next day, then is gone until the cycle is repetted. Is the engine oil level right?
  3. Cliff

    Cliff Member

    The oil level has been dropping lately. I checked the turbo / intercooler / piping thoroughly and there was no oil at all. I'm much more optimistic about the cost of this repair now.

    This article pretty much sums up exactly what my car has been doing. I guess it is the valve seals. I'll replace them and see if that fixes the smoking.
  4. beaver

    beaver southern zeds

    If you know how to use a vaccum gauge as a diagnostic tool/guide, use one before you start dismantling the engine. The reading should be easy to interpret, stem seals are gone after only 6 monthso_O, it also possible the guides are out of spec. On deceleration where does the needle on the factory boost gauge sit?
  5. Fists

    Fists Well-Known Member

    That's actually unusual, what's your cam breather/PCV set up?
  6. Cliff

    Cliff Member

    Well I dont have the factory boost gauge hooked up anymore. Instead I have a Haltech CAN gauge which on deceleration pulls anywhere from -14/15psi to -10psi (car is tuned via VE, no MAF sensor). I'll see if I can find some tools to do a leak down test today.

    My PCV system is setup with two oil catch cans so that the crankcase is sealed other than the intake valve cover breather vents. Both PCV valves on the plenum are plugged. Both PCV vents on the left side exhaust valve cover are plugged. Both PCV vents on intake valve covers vent to oil catch can and then atmosphere (legal where I live). Both intake pipes plugged where PCV joins. I made this change because I was popping the oil dipstick out under higher boost 15-18psi.
    ztothebone likes this.
  7. Cliff

    Cliff Member

    So I had a theory.

    If the intake valve cover vent and hose become clogged, would that nasty stuff get sucked back into the valves under vacuum?

    Well, the tubes to the catch can seem fairly clear so maybe not.

  8. Cliff

    Cliff Member

    Through the spark plug holes I can see shiny (assuming wet) oil on the pistons. Another vote for the valve stem seals.
  9. Cliff

    Cliff Member

    Another thought, I had to replace the intake valves on the right hand side and I lapped them in by hand. Do you think a bad valve seat would still show good compression?

    The most confusing part here is how out of the blue this issue started. Yes I replaced 6 valves and seals on the right hand side of the engine but Ive had zero issues for nearly 5,000 miles. So why would smoke show up like this out of nowhere and from both banks as well?

    Does excessive boost affect the valves in anyway? I only boosted to 21psi a few brief times never holding that pressure for more than a second.
  10. East Coast Z

    East Coast Z Well-Known Member

    Blue smoke indicates burning oil.
    Blue smoke on a trailing throttle (decelerating) indicates leaking valve stem seals.
    Blue smoke on power (accelerating) indicates worn or damaged piston rings.

    Think about it...........
    If the turbo seals are gone, the oil can only enter the combustion chamber via the inlet manifold, as it would be carried over with the air.
    If the throttles & induction hoses aren't contaminated with oil, chances are it isn't the turbo's.

    Leaking valve stem seals won't affect compression figures because the valve stems aren't exposed to the combustion chamber when the valves are closed.
    Martin Williams and Cliff like this.
  11. Martin Williams

    Martin Williams Well-Known Member

    I know this sounds silly, you said you lapped in valves your self. you didn't lap them in with valve seals fitted did you and you did do an ultrasonic head wash afterwards. Any ANY grinding compound residue left on valves, valve guides or valve seals will very quickly damage all of these. Just a thought!
  12. Bob Lloyd-Jones

    Bob Lloyd-Jones Oldreverbob

    A test for youValve guides & valve seals worn cause oil smoke when pulling a vacuum on a down hill run with throttles closed.
  13. Cliff

    Cliff Member

    Martin: I didnt lap the valve with the seals installed lol. But you do worry me with having the head dipped and cleaned afterwards. I cleaned up each valve and port with brake cleaner on a cloth, IIRC.

    I've got a buddy coming over this weekend to hopefully get this fixed in a 24 hour turnaround. I'll take some pics and let everyone know what we find ;)
  14. Cliff

    Cliff Member


    I've torn down the engine this weekend and confirmed that oil was leaking through the valve stem seal's.



    It seems that every single valve stem seal has failed. How is this possible?

    What could cause a new (1,500 miles) set of OEM valve seals to begin leaking all at the same time?

    My best guess would be something like excessive heat compromised the rubber seals, or low oil caused excessive friction and wear on the seals. Something like that would explain why they all failed, but also why they all failed at the same time. But thats just a blind guess.

    I'm just trying to make sure when I install these new seals that the engine will be solid once again.
  15. Shane001

    Shane001 Well-Known Member

    Did the seals look to have visible damage or deterioration?
  16. stumagoo

    stumagoo Active Member

    when my turbos seals went it was not into the pressure side but the exhaust side - I found when I dropped the dump pipe off the turbo it was full of we oil - that oil when the engine is running right burns and creates blue smoke - when it is not burning it impregnates all the exhaust components and can take forever to burn out once the seal is fixed
  17. Cliff

    Cliff Member

    Hard to say regarding the deformation because they get a bit deformed when I pull them off.

    The inside of most, look to have a slight circular scoring. I dont think that is from my removal because the scoring is circular and not up and down.

  18. Cliff

    Cliff Member

    Just thought I'd share some of the fixing here. Almost done with cleaning and restoring everywhere the oil burnt and gunked up. Anxious to get all this back together again.

    I cleaned the pistons with WD-40 and a toothbrush.

    I cleaned the valves with a green scotch pad (sprayed with carb cleaner), and a drill to turn the valves. Use extra extra EXTRA tape on the valve stem to ensure no damage from the drill - extra tape is cheaper than new valves...

    After cleaning the valves I re-seated each valve with permatex lapping compound. And checked the seals would hold water.






  19. pmac

    pmac Z,, IT'S COMPLICATED!!!!!

    Nice clean up.
    How are the valve guides? If they are worn that could cause your valve stem seals to wear prematurely.
  20. Cliff

    Cliff Member

    I was worried about the valve guides too but thankfully they were all within spec when I measured the play.

    I'm hoping to have this wrapped up by tomorrow so she can be back on the road Monday, but still a long ways to the finish line...

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