TT39 killing glowplugs

[deanwesterburg]

I was having problems with my engine being to lean at high speed and to rich at low speed. I decided to reset the needle valves to the initial 3 turns out and start over.

Now I feel like it's running well, but every few flights u go to start the engine and as soon as I pull the glow ignitor of it quits. When I pull the plug out and it looks like someone smashed the coil in and it looks white.

I'm lost on what to try next. A $7 glow plug every 2 flights is getting expensive!

Anyone else had this issue? Any ideas what is wrong?

[Don S]

It's leaning out if the plug is white. Air leak somewhere?

[Rob43]

If the TT39 carb is anything like the TT53 carb, it's not a sure bet to be easily resolved. I am speaking from ignorance of the TT39 carb though, so don't flame me. Might want to double check the rear bearing condition anyway to be sure it's not shedding particles.

[deanwesterburg]

I think I may have it fixed. I still never found what the default low end setting was, but I found another post about how to tune your engine on another forum. I went through this tonight and ran it through half a tank, but it was mostly hovering. I had a good strong stream of white smoke, good idle (A little rich still, but I would prefer that right now!) and no lack of power to jump into the air. Couldnt run it much over hover in my yard.

A summary of what I did was:

1. Open the main needle up to about 3 or 4 turns
2. Close the Idle Needle valve completely
3. Open the carb to 1/5 (TIP, use the Pitch curve screen on your radio and line up throttle with position 2)
4. Blow in the fuel line going to the carb and open the Idle Needle slowwly till the pressure is reduced and you can hear a little air going through the carb.
5. Turn your Main needle valve back to the recommended starting position (about 3 turns for me)

I still had to richen up the Idle needle about 1/2 - 2/3 turn from there to get it to run well, but it was a good staring point. If the weather is good tomorrow, I'm going to try to go fly it tomorrow night and see if my glowplug blues are over.

Hope it's not frowned upon to quote another forum as the source!
SOURCE = http://www.rcgroups.com/forums/showthread.php?t=205602

[deanwesterburg]

Well I tried the changes tonight. Heli flew great, thick white smoke, a I thought it was a bit rich. When I landed I waited for it to cool, pulled the glow plug, and it's smashed in and a bit white.

I measured the head temp as soon as the blades slowed down and it was 244 degrees Fahrenheit.

I don't find anything telling what temps to expect. Anyone have any idea what temps I should expect?

[deanwesterburg]

Here is an image of 2 of the glowplugs that have gone dead after 1 flight.


Any help or ideas would be greatly appreciated! I love the nitro, but at $7 per glowplug, this heli is quickly becoming cost prohibitive!

[Reid Williams]

Rob43 made tsuggestion to check your bearing. I bet that's it.

[deanwesterburg]

It's been a while since I posted this and I finally got around to taking this engine apart. It was Definatly the bearings!!!

I was shocked at how well it ran with so little of the bearing race left! Unbelievable! It's missing half the race (it was. Sitting, smashed up in the bottom of the crank case) and about 5 of the balls( all missing) !!