hi 2day i got my os engine finally working and running but now it has stopped running and when you try to start the prop jams and the engine doesnt start does anyone know what this is??? i have a new glow plug in it and it works fine. thanks

Take the plug out and try to turn the engine by hand (back and forth gently).
Then turn the engine upside down and repeat.

It could be a liquid jam, if too much fuel was primmed into it before starting.

My OS 20 does this all the time. It's just hydro-locked. Remove the glow plug and spin the prop a few times.

hi thanks. I did that but still wont run. Most of the time it locks.sometimes it starts and goes for about 6-7 secs then slowly dies. Any ideas on what it is and how to fix this proplem?? its killing me that i cant get it going.Also when it runs fuel splatters out the carb but none of the mixture needles fix this.

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Do you have previous experience tunning glow engines?

The problem could be many things: the valves should control the mix (if they are clean inside and non-damaged), you should be able to identify lean or rich mix just from observing how the rpm's die, the head temperature, etc.

Could the gaskets be hard due to age, so air leaks are possible?

Is the tank and plumbing new or verified?

no its my 1st model plane but the engine is over 20 years old. i think the valves are in ship shape as i have had them apart. I did notice that there was air bubbles in the fuel lines. could his stop the engine starting??? and why would fuel start coming out the carb???

OK, then, air in the lines seems to be the problem that stops the engine.

Somehow, the pick up line is sucking air.
A little crack or hole is the more frequent cause.
If the bubbles are really small, like making a foam, then they may be created by vibration of the frame being transferred to the tank.

Any type of bubble should be eliminated before you continue on.
Check the silicone tubes and the isolation (with wrapped foam) of the fuel tank.

I really recommend you to find experienced local help to trobleshoot and adjust your engine properly while you learn.

Check these sites for the basics:

http://www.airfieldmodels.com/inform...ines/index.htm

http://www.gettingairborne.com/engines.html

ok i will check for leaks in the tube. thanks.

Bubbles in the line means there is an air leak someplace. If your engine is flooding and locking up your fuel tank may be too high. The center line of the fuel tank should be about even with the spray bar in the carb. If your engine is inverted then the center line of the tank should be a taste below the spray bar. That's pretty general but it will give you something else to look at.

"Bubbles" in the line can be a sign of a problem, or just a little residual fuel foam - it would take someone with experience to see it first-hand to tell the difference, however, the fact that fuel is spurting out of the carb AND you're getting a hydrolic lock tells me that the bubbles have little to do with it.

It sounds like you are running very rich (Too much fuel in the mixture)

Close the needle valve completely and open it about 1 1/2 turns. Prime the engine by adding a few drops of fuel directly into the carb and start it. If it runs and dies (with no fuel spurting out of the carb), open the needle valve another 1/4 turn and repeat as necessary

The problem could be the rubber "O" rings in the needle valve assembly have dried out and cracked.

I have the same problem with my OS 20 R/C. If it's spitting fuel from the carb that usaully means to much fuel is getting in. One thing I found was that if the tank is a little to high or even with the carb, fuel will just trickle in and fill the crank. I gad to take the plug out and spin the prop. The other thing iis mmake sure your idle screw is set right. close all the way then back off 2 to 2 1/2 turn and check that the whole is half open, or closed depending how you look at it. I also found the needle valve set at 2 turns out is a little heavy. Start at 1 1/2 turns and work from there. Good Luck.