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3.3 piston hangs up on sleeve

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asimons07

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red creek ny
RC Driving Style
  1. Racing
i recently took apart my (2) 3.3's and my 2.5r engines and did a little maintenance on them. i didnt replace anything just made sure everything was in working order and clean. i did remove the piston, sleeve and crank from the block. when i reassembled them, all 3 motors have the same issue. the piston seems to get stuck at the top of the sleeve now. i just catches a little bit. still easily turns over but these have never done this before. I'm assuming this is my fault seeing how all of them do it. i was also thinking that since they came apart maybe they didnt go back together exactly the same, maybe the shifting of parts "thousands of an inch" has something to do with it? a motor is broke in and gets used to running with all the parts in the exact location. maybe just simple taking it apart allowed things to go back together off just a liitle bit and running a few tanks may make it go away? please any suggestions would be greatful... Adam
 
Are you 100 % positive that you didnt stick the pistons in backward. I mean it isnt hard to do. I done a 2.5 r motor that way once and it felt as if it would stick a lil at the stop. So i took it a apart again and swiched the direction of the piston and it worked perfect. So i would check that first before mounting them and firing them up so that way it doesn't cause the motor to blow.
Goood luck hope this may have help you.



asimons07 said:
i recently took apart my (2) 3.3's and my 2.5r engines and did a little maintenance on them. i didnt replace anything just made sure everything was in working order and clean. i did remove the piston, sleeve and crank from the block. when i reassembled them, all 3 motors have the same issue. the piston seems to get stuck at the top of the sleeve now. i just catches a little bit. still easily turns over but these have never done this before. I'm assuming this is my fault seeing how all of them do it. i was also thinking that since they came apart maybe they didnt go back together exactly the same, maybe the shifting of parts "thousands of an inch" has something to do with it? a motor is broke in and gets used to running with all the parts in the exact location. maybe just simple taking it apart allowed things to go back together off just a liitle bit and running a few tanks may make it go away? please any suggestions would be greatful... Adam
Click to expand...
 
well if I'm not mistaken I'm pretty sure i put the piston in so the notches on it face towards the flywheel and cluch assembly??? this is the correct way isnt it???
 
i say take it apart and look at the engine drawing very carefully and double check everything..should be ok..:) it happens dont worry its part of the hobby..
just remember if something dont move smoothly dont force it too..take it out and look at it..
 
an easy way to tell what direction the piston was facing is by the color of the surface. If it always had a decent tune the darkest portion in the middle will be slightly off center toward the exhaust port. At least that's what I've seen.
 
Lessen said:
an easy way to tell what direction the piston was facing is by the color of the surface. If it always had a decent tune the darkest portion in the middle will be slightly off center toward the exhaust port. At least that's what I've seen.
Click to expand...

+1 lessen is right on... there is a chance that all three happen to be in the wrong way and that is how you would tell the difference. If thats not it then you are going to want to make SURE that you have the engines togeather the correct way, as long as they are have no worries my friend CUS,

If you pulled matinence on them and didn't lubircate them before or after you put them togeather this is your engine's way of telling you that you still have good compression just give em some ARO or WD 40 and you may well find yourself with the same engines that you took apart.
 
i just checked the pistons, everything looks good. the part that i dont understand is that I've done this before with no problems? its not that I'm unfamiliar with nitro engines its that i can't see how this is happening? all the engines have great compression, all properly broke in and all run great. I've actaully tried one of the 3.3's and it runs just as good as before. pulls strong, doesn't over heat. I just dont know. i appreciate all the suggestions. Adam
 
I agree with GusMax86.
Are they still dry? ARO or fuel might be the only thing they need to make the mating surfaces move smoothly.
 
I added some fuel started it up and monitored it very closely. it ran perfect, no overheating and had plenty of power. after the run it was back to normal. Thanks for all the advise.
 
sounds like if the piston was binding at the halfway point in the cylinder you were at what they call the pinch point which is a good thing ,,,just means your motor is still sealing ,,if you could easely push the piston through the cylinder out the top without binding ..it would mean your engine is wore out
 

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