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  1. #1
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    Question Revo 2.5 dieing once warmed up

    I have a Revo with the 2.5R engine that sat in my garage with some busted parts for about three years. I finally got the motivation to fix it up and have got it running pretty easily. My issue is with the engine though.

    The car starts fine and runs pretty good initially. Once it warms up though it dies when I let off the throttle. The temp peaks at about 240 and the car won't restart until the temp drops to about 150.

    I bought the car brand new about 5 years ago (right before the 3.3 came out) and it has a little less than a gallon of fuel through it.

    Does anyone have any ideas as to what could be causing this? It is driving me nuts.

  2. #2
    Marshal Double G's Avatar
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    The engine is warming up where the sleeve expands enough so that there is blow-by thus you are losing compression. This is a classic sign of a worn piston and sleeve. You could get it repinched by Ray A Racing or buy a new piston and sleeve.
    The Super Derecho

  3. #3
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    I initially thought that, but the fact it only dies when idling down made me wonder. If it was losing compression, wouldn't it die whenever instead of only at throttle down?

  4. #4
    RC Champion Redsawacs's Avatar
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    keep workin' on the tune. Check the idle needle and make sure the throttle rod isn't holding it at an idle. I think you just need to reset the slide, idle needle, HSN, LSN and try again.
    "RED"

  5. #5
    RC Champion
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    I'd check compression, before I say anymore.

  6. #6
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    Short of tearing the whole engine apart, what is a good way to check compression?

  7. #7
    Marshal Double G's Avatar
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    With the glow plug installed and the engine cold, turn the flywheel and if you feel it tough to turn over then there is still some left. Otherwise a complete tear-down of the engine is the best choice and once you get the hang of it going from fully assembled to bare block (with bearings) would take at most five minutes.
    With the piston and sleeve out, push the piston up through the sleeve. If it stops even with the top of the sleeve or passes through, time for a rebuild.
    The Super Derecho

  8. #8
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    There is resistance, but not enough that I can't turn the flywheel by hand.

  9. #9
    RC Racer
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    chech the o ring

  10. #10
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    Well, after a complete engine tear down, I am sad to say it is the compression. Once cleaned, the piston top came up almost flush with the top lip of the sleeve. I guess I overheated years ago before I broke it and parked it. Now I guess it is either time to order a new piston and sleeve or go ahead and upgrade to a bigger engine.

  11. #11
    RC Turnbuckle Jr. fallonguy's Avatar
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    You can find Traxxas engines on ebay all the time I would get a new engine not a used one the 3.3 is around 100.00 to 120.00and most of the time cheaper then a new 2.5R and is a detect replacement to the 2.5.
    I wanted to put a really cool signature but I ran

  12. #12
    RC Racer
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    had the same prob my issue was a little piece of metal in the pipe blocking off the exaust when warmed up just check i was looking for answer for 3 weeks and got a new engine and fuel tanke to fnd out that little peice of metal was the problum lol

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