Evolution 40 engine poss air leak help appreciated

[steve b999]

Hi all

I am new to this forum and to model aviation generally. I have bought an alpha 40 trainer by hangar 9 which comes fitted with an evolution 40 engine. I took it to the local club in Maidstone yesterday where the helpful and friendly members helped me to trim the plane out and the chairman of the club took it out for its maiden flight. It flew really well.

There was some air getting sucked through from the tank which was a quick fix with some new fuel line. However we simply could not get the engine to tune.

At full throttle the engine would change from rich to lean with no adjustment meaning that it would start to over rev (I guess where it had leaned out too much)

I have tried a different prop (10x6) and new glow plug. I have now done an air leak test by blowing air into the carb fuel line and blocking the air entry hole. When under pressure air is escaping from around the spindle (where the prop goes)

I am assuming this should be leak free an it must affect the carburation if air is being sucked in through this area.

Is this normal to have air escaping from this area or do i need to go back to the model shop?

Also does anyone know the size of the thread on the fuel nipples/muffler pressure line as I sheared one off yesterday.

Thanks

Steve

[400blade]

that sounds like the front engine bearing is leaking were the crank exits wich is not normal for a new engine or even a old engine to do wich would indicate the probleme you are having also have you run the engine in with it being new

[steve b999]

The engine had been run in previously as it was purchased 2nd hand but unflown. I have taken it back to the model shop and they think the previous owner has left the fuel in it after running without after run oil being used. They are going to replace the front and rear bearings for me.

A good ad for after run oil.

Steve

[400blade]

iv never used after run oil and iv never had rust problemes or bearings fail the only real time you get that happening is when you use cheap rubish fuel

[tulipone]

I have a very similar problem and have previously returned the engine to Horizon for QC. They found no problem and returned it - just for the problem you described to occur immediately.

Did you manage to resolve this?