I have a new (slightly used) os 46. It ran great the first day out. But today, it's giving me fits. I've checked fuel flow from the tank, high end settings, low end settings, prop size, glow plug. It still acts erratic on the high end (tends to bog down or out).

It appears that there is a leak under the head. I removed the head and reseated it (no gasket). It still seems to leak. Would this cause the bogging problem at the high end? How do I get the head fixed?

Thoughts?

Exactly what type of OS engine is it, it should be on one of the sides, I know I was having the same problems with my 46AX, I tryed everything including flushing out the lines, in the end I swapped the number 8 O.S. plug for a A3 O.S. plug, the engine was not hot enough to keep the plug hot and the engine would quit, I changed plug and no problems.

J

I had the same problem with a OS 46 La blue and i changed the head the problem stoped but what engine do you have how did you check to find the leak i used light oil and sprayed around the glow plug and on the head bolts and found nothing.a friend told me to remove the engine and dip the top end of the motor in light oil and turn over the engine and poof leak! the head was warped hope that help.

Did you remove the gasket? O.S. engines all DO have head gaskets. It's made of aluminum, and looks like it's actually part of the cylinder head because it's so close-fitting in the groove where the top of the cylinder liner seats. It's there, though. If you use the point of a #11 blade, you can pry it up...just be careful to not bend it or get a crease in it.

Hi!
If you have tightened all bolts properly and put on a 11x6 APC prop, filled the tank with 5-10% nitro fuel containing 20% oil, put in an OS 8 or an Enya 3 glowplug, opened the high speed needle 2 turns, turned out the idle needle some, so that it doesn't stop fuel coming to the carb and primed the engine by holding the thumb over the carb intake and turn the prop 3-5 turns...then it should start and run just fine.

All,
It's a 46AX Max.
Jaka-did all the above with exception I was using a longer plug with an idle bar (can't remember the brand offhand). I'm going to try just an A3 plug.
Bax-the gasket may have been there as you suggested. I went ahead and ordered one. I might very well have a warped head from overheating...
Thanks all for the thoughts. I'll update once I see if anything changes.

Chivas,
You might check the distance from tank to carb that your fuel line travels, and how low the tank sets in relation to carb. Tank top should be about 1/4" above carb center line (more or less). Line from tank to carb should be as short as you can get it. Either or both of these items can cause a fuel draw problem. This results in engine starving for fuel, heating up, then quitting, unpredictably (20' high with 20' of runway left).

Steve

Epilogue:

Well, here's my final diagosis. The cowling did not have enough exit vents (plenty of in, but not enough out). The engine got hot. The 46AX has a brass AND a rubber head gaskets (from word of mouth, the rubber o-ring is new with the AX series). The rubber o-ring gasket melted and blew out. There is some kind of vent tube that exits between the engine case and the head but outside the brass seal on the cylinder head. This was leaking to the outside of the engine (visible). I replaced the head gaskets (both), increased ventilation around the engine. It seems to be working fine now.

Chivas,
Holy Cow! A rubber gasket? One has to wonder why they did that. Glad you had success. Troubleshooting balky engines can test your patience. Enjoy!
Steve