Hi all,

The engine on the plane runs good and idles smooth. The problem that I have is around the engine head its starting to get blacker everytime I fly, yet I havent had any engine problems. I thought it may be getting to hot but I figured it would cut off if that was the case. So does anyone have any ideas of what could be going on. I have a 10x6 prop and run 15% cool power fuel. I dont have a tach yet so I'm not sure what RPM's its running at.

Thanks for the help.
Nick

I use green 15% heli morgan fuel on mine

Most likely it's oily exhaust seeping out between exhaust manifold and muffler. Not a problem, other than maybe esthetically. If it bothers you, you can cut a gasket from a piece of manilla paper or gasket material from hobby shop or auto parts store. Or you can remove muffler, clean both faces with alcohol, lay in a bit of high temp silicone (get a tube of Permatex Ultrathrust Copper from auto parts store), re-attach and let cure for a day. Most guys just let the engine get a little dirty and clean up at end of season. I hope you fuel-proofed your firewall and engine compartment, and wipe the plane clean after a day flying--if not, oil will soak into balsa over time, pita to get it out.

Nick, Spencer,

You are both using fuels that don't contain any Castor oil in them.

This engine is based upon the now defunct OS.40FP.

Most engine 'gurus' and even OS themselves, say that this type of engine must use fuel that contains some Castor oil. Some meaning at least 5%.

My own experience is a peeled sleeve, in an FP that was run on Cool-Power green.

BTW, without Castor oil in the fuel, there shouldn't be anything that would burn to form varnish on the head, should the engine be run too hot. Strange!

I had a similar Tower 40 problem which was caused by leakage around the glow plug. A little machine work on the head flattened the offending unevenness and the problem is no more.

Jim

Thanks guys for your input. I will seal around the muffler and check on my glow plug to make sure it is making a good seal. Yea it was strange that this was happening but I had never had this problem before, so I will try your tricks and see what happens.

Thanks again

Nick