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Hi,

Has anyone out there got some tips for getting at and cleaning the turbo check valve without dismantling the engine?

  • Re: 914F Turbo check valve

    by » 5 months ago


    Hi Angus

    The access to the turbo may be an issue depending on your engine installation.  i am going to assume you are talking about the waste gate butterfly that is controlled by the servo motor.  Where the arm attaches to the bottom of the turbo check with a small light and look to see if it has a small bore on the casting that is drilled in to the wastegate shaft.  This is the lubrication port.  

    Once you locate the lubrication port the first step is to clear any buildup of carbon or lead.  I like to use a penetrating oil,  "mouse milk" and work the control arm until it is free of any tendency to stick. This is the standard aviation used to free frozen parts.  Once clean now spray in some nickel anti seize lubricant.  Because of the heat on the shaft it has to be a high temperature lubricant like this to resist sticking again.  This should be a regular thing to do with your turbo. 

    Cheers

    https://www.mousemilk.com/

    37695_2_914 lube port location.jpg (You do not have access to download this file.)

  • Re: 914F Turbo check valve

    by » 5 months ago


    Hi again Angus

    In some offline discussion with other turbo users, it was noted that the early type 914 turbo housings did not have a lube port.  In such a case you will need to rely on the wicking characteristics of penetrating oils. Mouse milk, or other penetrating oils, are very good at wicking into the shaft/bushing of the wastegate. To get the shaft and bushing clear however you will need to open the wastegate to the fully open position.  The shaft must move freely from full open to closed.  Once it is clear then, and only then, apply a very small bit of anti-seize to the bushing.  I want to stress, as I should have the first time, excess anti-seize can bind the shaft after it gets cycled at high heat.  I have heard stories of persons trying to lube the bushing with only anti-seize and the result is not good, it will stick very quickly.  Also to point out that you always use the nickel based and not lower temperature products. Mouse Milk, and most penetrating fluids, actually work very well as a lube as well.  I know of Stemme Motor Gliders that only clean and lube the shaft with penetrating fluid. 

    For anyone who has worked with aviation turbos this is standard practice, it is however not spelled out in the manuals from Rotax.  

    The bottom line.  If you must use leaded fuels then this should be a standard routine for any turbo equipped engine.  Should you see lagging performance be sure that the wastegate shaft is clear and not sticking.  I would do a cleaning of the shaft, as discussed above, on the annual if it was mine. 

    Cheers


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