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Waste gate is binding at times during the sweep test,the round gate sits too loose and bind at the top of ex hole,when lubed w never sieze it s better . Also having SS lockwire around its center holding nub makes the gate holding straighter and no more binding just before closing .914 has 450 hrs,what are your thaughts?
  • Re: 914 waste gate binding

    by » 7 years ago


    I know of a 914 wast gate sticking closed causing an overboost on T/O which caused the crank to warp requiring a total overhaul. The explained cause was a build up of lead around the gate from unsing only avgas and lack of periodic lubrication.

  • Re: 914 waste gate binding

    by » 5 years ago


    This is a constant problem with my older 914 which doesn't have the lubrication cross hole in the wastegate shaft. My standard procedure is to:

    1. In pre-flight turn on power long enough for the wastegate servo to move to full cable slack.

    2. Manually verify that the wastegate is free moving.

    3. If free moving fine, otherwise apply a small amount of MouseMilk and work the mechanism until freely moved and will return with the spring force.

    4. On every pre-flight run up, slowly go to full power while observing the manifold pressure. A sticking wastegate will over boost. If this the case perform steps #1-#3.

    I have found that MouseMilk worke the best as a wastegate lube for me. Other suggestions??

     


    Thank you said by: daniel calderon

  • Re: 914 waste gate binding

    by » 4 years ago


    I just encountered the loose wastegate issue with my 914, 1997 vintage, 1100 hours since new.  The TCU light came on and the Bowden cable was found kinked at the wastegate arm.  With the cable disconnected the arm moved freely (no friction) but the arm would snag intermittently on something internal just short of the wastegate closed position.  With the muffler removed it was seen that the wastegate flapper was so loose on it's pin that it could flop far enough over the edge jams in the exhaust outlet port and halts travel.  One user commented he used safety wire to tighten the flapper, but I'm concerned that wouldn't survive the heat for long.  I'm considering making a clip on shim (like a circlip) out of 2000 deg. F Alloy X sheet stock.


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