Ernie Misner

Domnimon, if it is still not shutting off with a different front bearing in it, it has to be leaking air at the carb mount or the backplate. Take a good look at these two areas, and if necessary, try installing them with hi temp silicone sealant.

Ernie

Domnimon

Hi ernie, i was thinking that too. i really don't think its the front bearings either anymore. The bearings seems to be tight and there is no play or any movement at the prop shaft. also there is no fuel or oil leaking there. engine does have good power. this leads me to think the air leak is at the carb or back plate. i will look into these areas, if still doesn't shut down, i might just replace the carb with another from Justengines if i can get one. thanx again

IronCross

I have several Irvine .53's... I have one that will not shut down but runs great... I checked/swapped the carb, checked the back plate and everything else I could think of and nothing helped... Even replaced all the O rings and gaskets... ... Finally out of desperation I attached a length of fuel line to the inlet on the carb covered up the exaust and intake on the carb with my fingers, held the engine underwater and blew like h*ll. It was easy to see the only leak in the engine was out the front of it.. I lloked at the replacement bearings I had from Just Engines and no way are they going to seal the front of the engine... I can see daylight through them... It would seem that for some reason the clearance between the front of the crankshat and the block is a little too large for the oil to make a good enough seal there and thus leaks air... As soon as I have occasion to tear down a "good" .53 I will mic both and see what the differance is...
Like I said I have several of the .53's, 2 .46's, and 2 .25's... They all run great except for this one that doesn't want to shut down....

Domnimon

Hi ironcross, on your engine that leaked air, did you have any play at the crankshaft when you touched it?, mine seems very tight there. Do you think it would be a better idea to just exchange this engine for a new irvine 53 from JustEngines?....thanx

Domnimon

Well i performed a similar test as ironcross by holding the engine underwater and blew into a fuel tube connected to the fuel nipple while sealing the carb opening and exhaust port. i did noticed bubbles coming from the front of the drive hub. i have it pictured below. there is a small gap on the gold ring thats where the air leak appears to be. My question is can something be placed there, like a rubber washer or something else to prevent air from escaping?...thanx