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Help! Rotax 503 - PTO bearings - how much axial play?

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  • Help! Rotax 503 - PTO bearings - how much axial play?

    Hi engine guys (gals?).

    I just managed to get the small gear off the crankshaft (to change the axial seals). And checking the two PTO side bearings i found they have a lot of axial play - not radial.

    Another pilot told me, he uses a normal puller and a smack with a hammer to break the seal and pull it off.

    I really had a hard time doing it using a homemade threaded puller like the one from Rotax.

    And I did give it some smacks with a hammer (not a BFH) to no avail. In the end, I used an electric impact wrench with the puller.
    That helped so much, that I could break the seal myself with a wrench.

    But now seeing that axial play I wonder, if I have damaged the bearings? They don't feel damaged (rough or notchy), just this axial play.

    I bought the engine in the late 80's and it's still a virgin. It has the steel o-rings to fix the inner bearings, it's a provision 4, but the gearbox has 12 spring washers,
    so it's not the really old model.


    Last edited by rcflier; 06-18-2017, 01:15 PM.

  • #2
    Okay - the FAG bearing has the suffix "C4", which means it'is made with a lot of play. So it's ok as I thought. But now I can see, the engine is the old type with the small pieces of rubber
    to stop the bearings from turning in their seats. And one rubber piece is missing - arrrghh! I have to order some gaskets and other stuff. A fan belt plus both pulleys. So I can ask
    the shop in France if I can buy one rubber thingy also and not the gasket set for the entire engine....I have searched for the small rubber piece a long time and enough is enough.