TT130 4 stroke
 

Outside of problems with fuel leaking around the glow plug, any other problems encountered with this engine?
After about 30 flights mine TT130 lost power and started making a grinding noise. I sent it in for repair and it required a new cylinder, and piston. Since then I have not had any problems, but I have not put a lot of flights on it. A flying friend of mine purchased his TT130 at the same time, he has about 40 flights and it had been running fine. A few days ago his started to lose power and he has had to send it in for repairs. Curious of any other users have had the same problem.

RE: TT130 4 stroke
 

If you search the threads for this engine with posts started by me you will see the reason why it leaked around the plug and why you needed a new piston and liner.

The threads were not tapped deep enough and the head alloy was soft so it didn't take much effort to strip the glow plug threads and send chunks of alloy into the combustion chamber.

IMO they went too far in the weight saving of the piston as i've heard a half dozen accounts of the pistons disintegrating in this engine.

RE: TT130 4 stroke
 

Thanks for the reply, I was aware of the glow plug problem. I didn't know that this was also the cause of the piston failure. I will research the threads.

RE: TT130 4 stroke
 

I suspect the glow plug problem is that TT may have done the same thing that OS did with their engines. They machined the glow plug hole and threaded it partially for a special 4 stroke glow plug that is made. The OS F and the Fox Miracle glow plugs for example. The special glow plugs have the bottom tip machined smaller in diameter to fit into the recess at the bottom of the glow plug hole. Thus if you use a regular glow plug, it bottoms out on the inside shoulder of the hole and doesn't seat all the way down, causing it to leak of course. Stripping it out is easy then as you think it hasn't gone all the way in and you try to tighten it up more. Obviously if the metal should break off into the combustion chamber it will cause deleterious effects.

I beleive that OS did this to improve the inside combustion chamber shape for better engine running. But of course they could have done it just to aggravate everyone too.

Here you can just see the inside machined shoulder in the glowplug hole on the OS four stroke engine.
http://i248.photobucket.com/albums/g...ug_hole_02.jpg

The typical OS F glow plug with the machined tip on it to fit into the special glow plug hole.
http://pics.towerhobbies.com/image/o/osmg2692.jpg

Fox Miracle glow plug
http://pics.towerhobbies.com/image/f/foxg1515.jpg