Dear OS,
I have a 46 FX engine . Its about two years old now have made over 50 flights. The problem with my engine was that it use to get over heated in a very short run and use quit in the flight . My instructor told me that their might some sort of gumming maybe in the crank case with which a such a problem is occurring.

I opened the engine and took out the bearing . I found that their was a bearing ball missing in the front Crank shaft bearing. Very Surprising to me. Now I have changed the bearings.

For a few days it worked well but now again a similar problem . The engine has excellent compression when cold but after some time it loses the compression when hot.

What should be the problem?

Thanks

Sharad

Sharad,

It sounds like your engine's piston/cylinder fit has gone bad. There should be compression when the engine's warm, and it should be able to start warm or cold. You'll need to replace the piston/cylinder assembly to recover the engine's performance.

Dear Bax,
Can you tell me what would be the reason of a missing Ball in the bearing.

And should I change the just cylinder or both or just the piston.

Regards

Sharad

With O.S. Max engines, we have never seen an intact ball bearing assembly with a ball missing. If balls were missing, the ball retainer and other internal engine parts have been damaged.

If a ball is destroyed for some reason, usually the rest of the bearing is destroyed, also. It would also be difficult for most front bearings to have a ball "pop" out because of the dirt shield and the drive washer in front of it, and the crankshaft and case behind it.

With non-ringed engines, you must replace the piston and cylinder liner as a set. That's the only way they are sold.