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  1. #1
    RC Competitor
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    Traxxas 3.3 engine compression

    I have a traxxas 3.3 motor on a tmaxx and I was wondering is it easy for you to turn over the engine by pushing the flywheel with your finger because on my engine it is fairly easy to turn it over even when the piston is a the top.Also when its running and gets to around 220-240 it just shuts off and it keeps doing it.Thank you for your incites.

  2. #2
    Marshal Double G's Avatar
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    When the engine shuts off when warm only to restart when cold: lost compression. When you can spin the flywheel with little resistance on a cold engine: lost compression. When you can push the piston up to the top and through the top of the sleeve...
    The Super Derecho

  3. #3
    RC Turnbuckle Jr. fallonguy's Avatar
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    Yes sounds like the engine has lost compression. You can replace the piston and sleeve but some times it's just better to replace to whole engine.
    I wanted to put a really cool signature but I ran

  4. #4
    RC Racer
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    Yea that is the way a worn out motor feels. I always think it is better to just get a whole new motor. Rather then rebuilding a motor that has had problems before. You may spend that money only to find out the motor has bad bearings, or conrod. How many gallons did you get through it before now?

  5. #5
    RC Turnbuckle Jr. Nitronaught's Avatar
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    Quote Originally Posted by JustynKace View Post
    Yea that is the way a worn out motor feels. I always think it is better to just get a whole new motor. Rather then rebuilding a motor that has had problems before. You may spend that money only to find out the motor has bad bearings, or conrod. How many gallons did you get through it before now?
    If the conrod hasn't snapped and there isn't a broken piston or damaged engine bearings,,, I find you can get 1 rebuild out of a 3.3 without having to replace bearings OR the conrod.

    Trick is to inspect the conrod for wear bu putting 1 drop of 3 in 1 oil onto the conrod where it connects to the crankshaft, turn the flywheel back and forth. if the oil squeezes out all the way,,, time to just get a new engine.

    Me, I like rebuilding mine. $35.00 for a new piston and sleeve, break it in,,, go..... Then if I have one that has a bad bearing and a bad conrod,,, I go with a new motor.

    Lately I've been buying a new Piston sleeve and conrod for like $60.00, pick up some new engine bearings and for $90.00 I've got a new engine with upgraded internal bearings... I've also been porting my sleeves and polishing the tar out of my crankshafts.... SO I don't just have a rebuilt 3.3, I have a modd'd 3.3 that really moves for $90.00...

    Then again,,, I enjoy working on my RC's as much as I like to race and bash them....
    Founder of H.U.A.
    Hop Ups Anonymous

  6. #6
    RC Champion
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    You could lean the low needle to keep it running for a while longer.
    erbe emaxx 26maxx s27revo 18tmrevo XXL platinum

  7. #7
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    I've been wondering the same thing about my TRX 2.5 so today I went into the local hobby shop where they have a new Revo 3.3 sitting on the counter. I reached under the chassis and gave the flywheel a spin with my finger so I could compare how my 2.5 feels. I got it to move a little bit and then that sucker WOULD not budge! I'm by no means an expert, but something tells me if you (and me) can turn our flywheels over kind of easily with our finger, then there might be a problem. I'm guessing my engine is probably about shot. . . time for a new one.

  8. #8
    RC Turnbuckle Jr. Nitronaught's Avatar
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    Quote Originally Posted by Vvajk View Post
    I've been wondering the same thing about my TRX 2.5 so today I went into the local hobby shop where they have a new Revo 3.3 sitting on the counter. I reached under the chassis and gave the flywheel a spin with my finger so I could compare how my 2.5 feels. I got it to move a little bit and then that sucker WOULD not budge! I'm by no means an expert, but something tells me if you (and me) can turn our flywheels over kind of easily with our finger, then there might be a problem. I'm guessing my engine is probably about shot. . . time for a new one.
    You can't compare en engine that's been ran to an engine that's never been fired up or broken in when it comes to compression... Many new RC engines are so tight brand new they get stuck at TDC....
    Founder of H.U.A.
    Hop Ups Anonymous

  9. #9
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    That's right, if you want to check your old engine take the head off, then rinse the cylinder with a little wd-40. If there's no tightness at the top of the stroke then the "pinch" is gone. That doesn't mean it's shot though, I would try to lean the lsn so it will idle.
    erbe emaxx 26maxx s27revo 18tmrevo XXL platinum

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