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OS 55 ax problems

Old 10-14-2015, 06:21 AM
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bigbird007
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Default OS 55 ax problems

I have a couple of OS 55AX engines, both have developed the annoying habit of dying in the air for no apparent reason. I've redone the fuel systems, changed the glow plugs (A-8 os plugs) and using the pinch method, checked the needle valve settings. The engines are not overly hot upon landing.
Is there some problem with the new carb? These engines both ran great out of the box.

I've run out of ideas, can anyone help?

Thanks
Bob
Old 10-14-2015, 07:57 AM
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warhwk
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Have you checked the length of the fuel tube length to the clunk. These can stretch after use and impede fuel flow during flight.
Old 10-14-2015, 09:21 AM
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Yes, I've completely redone the fuel system on both.
Old 10-19-2015, 11:42 AM
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Bax
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You may be getting "fuel foaming", which is where air is being agitated into the fuel tank, causing the mixture to go lean. You could have a cracked line in the tank that becomes exposed to air after the fuel is drawn down a bit, the engine could be set a bit lean and is overheating a few minutes into the flight. And so on and on. There can be a lot of reasons.

If the engine's been used a lot, then it could be wear, and you've been leaning it a lot to get power back.

Put the engines on a test stand and see how they run. If they'll go "all day", then the problem is in the airframe/engine/fuel system combination and will need to be investigated.
Old 10-20-2015, 04:48 AM
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I had this problem. I removed the Fuel Inlet and Needle-valve Holder Assembly and found some dirt. The engine runs good now after cleaning out the dirt.
Old 10-20-2015, 05:16 AM
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bigbird007
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Thanks, I've had such good luck with OS over the years, I was wondering if they had introduced a problem with the carb on the AX's. If the responses are any indication, they haven't.

This this seems like the most likely solution, I'll let you know.

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