Power Valve Blade keeps coming loose or off the stud

Joe Ricard · Posted: Thu Sep 20, 2012 6:44 am Post subject:

After further review I found I am missing the smaller of the two springs on the green bellows. And the stud is screwed into the blade but was being held proud of the exhaust chamber by the thick O-ring.

So ordered all new stuff for the exhaust valve. and the Delrin simpler version of the spring tool as recommended above.

Now the question is how much travel should the blade have up and down.
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Arrow AX-8/ Rotax Sr.

Eric Alexander · Joined: 19 Jun 2011 Posts: 121

Slight deviation of the topic, but recently I had a RAVE valve that was a bit bound up in the metal bracket the bellows attaches to. I cleaned it thoroughly and had to use a wire brush to the bracket's guide hole to get the blade moving freely. Now I'm curious if anyone applies any type of grease or lubricant to the blade shaft to cut down on friction at this point?

Keith Buffo · Posted: Sat Sep 22, 2012 2:58 pm Post subject:

Eric, there's usually more than enough oil around the PV. The only time I've seen things get caught up in that area is from a burr on the stem after it was replaced... Caused by grabbing the stem with a vice grip to screw it into the blade.

Joe, as for length/travel... I think there is a measurement in to manual with photos of how to check it. But how I check it is this: once the whole thing is reassembled, right before reinstalling onto the engine, I will compress the bellows and check that the plateau/flange on the stem/shaft aligns with the outer surface of the cork gasket. (Do it and you'll see what I mean.) The resulting measurement is very close to what's in the manual, but not always easy to achieve securely with worn parts.
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Keith Buffo
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Joe Ricard · Posted: Sun Sep 23, 2012 4:27 am Post subject:

73.5 total length.

Pulled the cover put my finger over the bellows and piston. starter the motor and I could see the assembly quickly moving up and down. Then with slight pressure I revved the motor and the piston would move out.

Put is back to gether and everything seemed to work. I thin it was hanging up on the paper gasket. New parts get he Monday.
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Arrow AX-8/ Rotax Sr.