air leak on nitro engine
 

hi guys
guys i have question here, how do you know that your engine have air leak and how to fix it? thanks

symptoms: easy to flame out even with fresh glowplug and proper mix air / fuel setting.

Check your front bearing from excessive fuel leaking
Check your backplate rubber seal.
Check your carburetor neck rubber seal.

Wore piston sleeve and old glowplug also make easy to flame out too.

You can fix it with Permatex Seal Gasket ( look messy ).

I rather buy new seals and new front bearing

also, if you have an irratic idle, thats another sign of an air-leak. There is a sealer that comes in a small white bottle. The sealer is called "stop Leak" and it black and turns to rubber. I use it on all my engines for everything that seals. It is about $6 and very easy to use. It prevents things like running to lean causing the front bearing seal to go.

thanks guys to reply my post,
i think fixing the back plate and the carb is easy, how bout the air leak came from the front bearing, should i take out the front bearing and replace it , and what kind tool of tool to take out the front bearing?thanks

There is no easy way to open front bearing without proper tools.

Go to hobby shop to borrow the tools or be very sweet to a friend who has one.

so which one is better for the front bearing rubber seal or metal seal, just dont know which one is the better,thanks

I'll save you some work. The seal on front bearings are there to keep dirt out of the bearing and are not there to seal the engine. An engine gets it's seal from the air gap between the crank and the case, this area fills up with fuel and seals the engine. You can see light through a brand new bearing and a lot of engine (airplane) don't even have seals.

Take a look on this
http://www.rchobbies.org/engine-tuning.htm

Jeff that was good info, Thanks

You can get gasket sealent from the auto parts store. I forget the name. Its red and rated for high temp. Just tell the guy your looking to seal a gasket.

Dont worry about the bearing for now, seal the back plate and carb and see if your problem is gone.

thanks guys
today i,m gonna take out my engine do some test like jeff said, once again thankssss :) :)