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  1. #1
    RC poster
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    Nov 2011
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    Exclamation Compression is very high in cylinder and seems to lock.

    Hey guys, i have a Revo 3.3 and i'm going to junk it if i cant figure out what to do or have to buy a whole new motor.

    So i was out a few days ago doing some high speed runs and tuning it for the 90 degree weather. I had a good time and i went through a few tanks like normal. Then, one tank, i forgot to fill it up when it got low so it ran dry out of gas. I filled it up, then tried starting it. I put the glow plug heater in (its a pull start), but the glow plug didn't respond on the indicator. I took out the glow plug and saw that it looked normal, but it just wouldn't light up when i applied the glow plug heater. I went out and picked up another glow plug. I put it in and forgot to fill it up so it ran dry out of gas again. I filled it up and applied the glow plug heater to try starting it. The glow plug didn't respond. I toook it out, and instead of it looking normal, the filament inside the plug was completely gone . So i put another plug in and tried starting it the glow plug responded (why wouldn't it it's brand new) and I pulled the rip cord, but the engine wouldn't turn. I took the head off to see the cylinder and found that there was a bunch of metal in the cylinder and on the piston (pieces of the glow plug filament melted). It was pretty attached to the piston sleeve and the piston. I cleaned it off and put the head back on. I then tried starting it. The glow plug heated like normal, and i could turn the engine. I started it, then got a few feet down the street, and it cut off again. The glow plug didn't respond when I checked again. I took out the plug and noticed that thew filament was still there, but the engine wouldn't turn. I took the head off again and saw that there was more melted glow plug fragments in the cylinder. I cleaned it, put in a new plug, and tried cranking. It did turn, but it was very hard to because the compression in the cylinder was unusually high. The piston slid up and down in the sleeve very smoothly. The only think i did notice was that after the piston gets to the TDC, it would normally want to go down, but as I turned the flywheel just a bit more, it kind of locked there as if there was a physical object preventing the piston from going down. I tried pulling harder. It then came out of the lock and went down. This happens every time the piston goes up. I have to pull pretty hard to give the piston enough momentum to get past the lock and go back down. The lock isn't very hard, but there are also no more pieced of melted glow plug in the cylinder. My current thought is that when the engine siezed because of there being melted metal in the cylinder, it might have damaged the crank or the rod or something.

    For now, I really don't have the time to disassemble the whole engine to see what's wrong. If you guys could give me an idea of whats wrong and what needs replacing, that would be great. I don't have the money to buy a whole new motor or a new car.

    Thank you for your help.
    Last edited by Squerl101; 07-22-2012 at 01:34 PM. Reason: Misspellings

  2. #2
    Marshal Double G's Avatar
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    May 2008
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    You should have stopped when you first noted metal in the engine.
    Need to tear it apart and see what happened. My guess is the skirt became brittle from high temps and broke off.
    The Super Derecho

  3. #3
    RC poster
    Join Date
    Nov 2011
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    You are right. I just took off the sleeve, the bottom of the piston cracked off and the other half is sitting at the bottom of the crank case. Looks like I need a new piston and sleeve

  4. #4
    RC Champion
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    If u decide u want to sell it let me know (;

  5. #5
    RC Turnbuckle Jr.
    Join Date
    Jun 2009
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    Quote Originally Posted by Squerl101 View Post
    You are right. I just took off the sleeve, the bottom of the piston cracked off and the other half is sitting at the bottom of the crank case. Looks like I need a new piston and sleeve
    And new bearings too, as the ones in the block are trashed now!
    Look out for the tree/crunch!

    LiPo? Naw NITRO!!

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