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View Full Version : Discussion Few semi-noob questions...

RedStarArmy
Feb 20, 2009, 04:46 PM
Hey, I've been flying for a year and still using original engine and plane. It's the pts mustang with the .455 evo engine. Got a few questions that i hope you guys can help me out with...

1. Been having engine problems and tried replacing my glow plugs with new ones. After I put in the new glow plug, engine sounded the same so I replaced it with original. Now having only run the engine for a min or two on the new plug..should it be covered in black soot..probably oil..when i take it out? is that normal? And can I just throw it back into my field box, or having run the new plug with all the crap on it and leaving it exposed in a box will ruin it?

2. I have used my engine for right around one year now. I have started to notice slight play in the crankshaft and the prop. I am able to move the prop slightly (back and forth, in the horizontal plane) just a bit, maybe a few millimeters(by holding one of the prop tips..i can pull and push in the same plan that the plane is in and it moves a bit). I'm not sure if this was always present. The prop itself is tightly attached so its the actual crankshaft thats moving..is this normal? when i asked a few club members they said its probably just normal wear and tare and not to worry about it, but since my engine is not performing as it used to..im now wondering. What does this mean if its a problem..ie what component is damaged and can it be fixed? I've always heard about bearing problems..can this be it?

3. I've never taken an engine apart. I always read that people are checking their pistons, walls, and bearings in their engines. How hard is it to take apart an engine and than put it together (so itll work again :D ). Anyone have some good links with info on that specifically, with pictures and all..


Thanks a lot in advance.
blademaker22
Feb 21, 2009, 12:00 AM
As for question #3: If you feel so inclined, you might as well disassemble it. With two stroke engines, if all the parts fit back in, then its assembled correctly :) . They are ridiculously simple. You will just need to make sure that the holes in the sleeve are aligned with the ports in the cylinder. I believe most engines have a tiny notch at the top of the sleeve that corresponds with a tiny pin at the top of the cylinder to ensure proper alignment.
RedStarArmy
Feb 21, 2009, 08:48 AM
do I have to worry about making sure the bolts are properly tightend when i put it back together..as in is there a special torque to use..or is tight..tight? Also, anyhting else special I need to know if I would take it apart, ie..reoil parts before i put it back together?


Anyone else on the other questions? :)
Chip01
Feb 21, 2009, 09:48 AM
You have said nothing about engine adjustment. Sooty glow plug sorta indicates running rich.

I have a TT Pro 46, that is so slick inside, the prop will rotate on its own weight until it reachs Top Dead Center where the pinch point is. It runs great. So an easy to rotate prop is not a real problem. If you are having push pull issues, and it sounds like you are, it could be the main bearing breaking down (wearing loose so to speak). Remember when the prop is turning it is pulling forward and putting a load on the main bearing inside the engine. That's one reason why it is a ball bearing. Could be a bad bearing and needs replacement - not hard to do. Bearing dealers have instructions on their web pages on how to do the job.

If there is nothing wrong with your engine except adjustment of the fuel flow (e.g. tuning the engine), then there is no reason to tear it down.

As for torque, using allen wrenchs, just make sure things are really up tight. And check after first run to make sure they are still tight. Do remember you are using steel bolts into aluminum threads - over do it and you will strip out the threads.

Cheers,

Chip
qb40h
Feb 21, 2009, 11:20 AM
As for question #3: If you feel so inclined, you might as well disassemble it. With two stroke engines, if all the parts fit back in, then its assembled correctly :) . They are ridiculously simple. You will just need to make sure that the holes in the sleeve are aligned with the ports in the cylinder. I believe most engines have a tiny notch at the top of the sleeve that corresponds with a tiny pin at the top of the cylinder to ensure proper alignment.


It is easy to put them together wrong. You can get the sleeve in backwards or misaligned. You can also get the conrod on backwards. The sleeve and cylinder are the same thing. Just what how you took it apart.
RedStarArmy
Feb 23, 2009, 10:30 AM
alright thanks..anyone else can help me out with the first 2 questions?
MrGreenSpeed
Feb 25, 2009, 09:43 PM
Q#1 sounds like Your running too rich, put the plug in some thing to keep dirt from getting on the glow coil.
Could be bad fuel..?// hard to say with out more detail on how bad it's running.


If there is nothing wrong with your engine except adjustment of the fuel flow (e.g. tuning the engine), then there is no reason to tear it down.
I agree with this 100%

Q#3
You can find video clips on youtube showing how to replace bearings in R/C engines.
It's not hard You just have to be careful.

Jeff