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  1. #1
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    3.3 Motor Rebuild

    So I finally gave up on this motor and decided to rebuild it. It was running great for almost a year and then just decided to start acting up. I noticed a busted motor mount and that I could turn the flywheel by hand all the way around without a lot of resistance. So I am thinking I just didn't have the compression I needed to keep it running right any longer. With that being said... I have the motor tore all apart and wondering if I need to replace the bearings on the inside of the motor. I plan on replacing the piston/sleeve and o-rings. The carbertor looks pretty beat up, but I think I can clean it up pretty good. Do you guys recommend replacing anything else while I have this thing tore all apart? Here are some photo's of the motor, it actually looked pretty good I thought on the inside. Not sure why it started acting all wonky. Any advice/comments are appreciated.

    Thanks,



    [IMG]https://picasaweb.google.com/lh/photo/gpXdIDH-ALd8lPU***eV7NMTjNZETYmyPJy0liipFm0?feat=directlin k[/IMG]




  2. #2
    Marshal Double G's Avatar
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    Pics are not showing up for me. For the price of a new piston, sleeve, rod and bearings, you could get a new complete engine off of eBay. But if you want the experience and the bragging rights of rebuilding then you could go that route. I would replace what I have mentioned along with the o-rings in the carb and backplate.
    The Super Derecho

  3. #3
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    Thanks for the information. Yeah for some reason the image link is not working. I will try a different way when I figure that out. I will try rebuilding the motor once. I just wanted something to learn. It does look like a lot of precision work though. Might not be the smartest thing I have ever attempted. If all else fails, I know where to buy a new motor. :-)

    Thanks again,

  4. #4
    Marshal Double G's Avatar
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    Go to the Support button up top and under the engine section there's a write-up w/pics on how to do it.
    The Super Derecho

  5. #5
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    Yes, thank you. I found those earlier today.

  6. #6
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    This will bring costs up for you, but you're committed now......get bearings!
    If the bearings feel good you can try breaking in the engine first, but after that you should swap them out. One toasted bearing = one toasted engine.
    erbe emaxx 26maxx s27revo 18tmrevo XXL platinum

  7. #7
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    I can't seem to locate a part number for them... And how to I get them out without destroying them or the motor housing?

  8. #8
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    Put the block in the oven at 250-300f, and tap the block on a piece of wood, the back one should fall out.
    erbe emaxx 26maxx s27revo 18tmrevo XXL platinum

  9. #9
    Marshal Double G's Avatar
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    ....in the oven for about 15 min. For the front take a socket small enough to fit through the rear bearing but big enough to push against the front and tap it out.
    The Super Derecho

  10. #10
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    Here are the images:








  11. #11
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    Doesn't look too bad.
    erbe emaxx 26maxx s27revo 18tmrevo XXL platinum

  12. #12
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    I didn't think it looked all the bad either. It has a nice honey color to it. The inside of the lower end looks black on the inside but I am thinking that is normal. Just odd the way it started acting up and resetting the needles to factory and it wouldn't even run. I tried 4, 4.25, 4.5 on the HSN and 2, 2.25, 2.5 and smaller units plus visible flush on the LSN and all it would do was stall and sputter and was just plain grumpy. It was 70 degrees outside too. I have reset to factory before with success. Also put in 2 new glow plugs and all new fuel tubing.
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  13. #13
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    For the price of the bearings I would just buy a short block with bearings in it allready for $15 shipped on eBay.

  14. #14
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  15. #15
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    Yes, definitely seeing that rebuilding the motor is cost prohibitive. By the time you add up all the stuff you are looking at about $100 or more. :-(

  16. #16
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    New motor is about $115. Your better off buying it new. If you have the money your better off buying an OS engine more power less problems.


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  17. #17
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    I might buy a new one and rebuild this one as a backup with just a new piston and sleeve. Honestly, everything looks really good on this thing as side from the low compression I mentioned earlier on the thread.

    Which OS motor would you recommend for the Revo 3.3 as a direct drop-in replacement?

  18. #18
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    I've rebuilt well over 20 TRX engines, for myself and others. Here's the rule I follow.

    1. If there was an internal part failure, bearing, piston skirt, conrod. I would at least replace the conrod, P/S and bearings after a very close visual inspection of the crankshaft and the cooling head (look for pitting in the head). If it's more than the Piston and sleeve and conrod to be replaced it's cheaper to buy a new one from a chop shop on Ebay.

    2. If it's just a worn P/S I check the conrod at the crankshaft by putting a drop of household oil or 3 in 1 oil onto the part of the conrod that connects to the crank. Then turn the flywheel back and forth. If the oil squeezes out completely when moving the flywheel it's time for a new conrod. If not a new P/S should do the trick.

    3. I find usually the first rebuild of a worn P/S just requires a P/S (piston and sleeve), but always check your conrod...... You can get a new, pulled piston, sleeve and conrod off one of the Ebay shops for $60.00 or less......

    4. A New pulled motor is about $105.00 shipped (3.3 pulled off an RC) so yeah, cost is a factor.....

    5. If you are in it for just the experience and the fun, rebuilding your engine is great, for some added performance (not very much) drop some ceramic bearings in it, you will get a few more functional RPMs out of the deal.
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  19. #19
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    Cool, thanks for the advice.

  20. #20
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    Got all the bearings out. The oven trick is great. Not sure why it worked, since I would have thought a steel bearing inside an aluminum block would have gotten tighter...

    Does anyone have the proper part numbers for the bearings and seals? I see a 2.5 bearing kit but don't know if that will fit. I also can't seem to locate the TRX 3.3 parts list on the Traxxas website. I have all the other ones + TRX 3.3 manual. Just missing that list bit.

    Thanks again for everyone's help.

  21. #21
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    Scratch the part list for the TRX 3.3. I found it. Sigh...

  22. #22
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    Quote Originally Posted by jarod_rodriguez View Post
    I might buy a new one and rebuild this one as a backup with just a new piston and sleeve. Honestly, everything looks really good on this thing as side from the low compression I mentioned earlier on the thread.

    Which OS motor would you recommend for the Revo 3.3 as a direct drop-in replacement?
    OS 21TM this engine is a beast and drops right in like stock.


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  23. #23
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    Which way does the internal bearing go back into the block? It appears to have 1 side with a small cover on it. Is that facing the bearing socket or away? The engineering document, doesn't reflect very well.

    Thanks.

  24. #24
    Marshal Double G's Avatar
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    I run rear bearing without the shields and the keeper towards the rear.
    The Super Derecho

  25. #25
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    Thx, that is what I did. I still had the old bearing on the bench and you could see the discoloration on the part of the bearing that was exposed to the elements. The motor is back together now and is extremely tight again. So this should do the trick. Now let's just hope the carburator is not shot.

  26. #26
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    3.3 Motor Rebuild [Update]

    Hi Everyone, just wanted to post an update and let you all know my project is coming to an end. I finally had a nice day to fire up the rebuilt Revo 3.3. Once I started on this "Motor Rebuild" it ended up being a complete truck tear down and rebuild. I took it down to bare metal and completely removed everything. Had a pile parts but cleaned everything up, all screws, diffs, servo's, shocks etc... I had to completely rebuild the diffs and shocks as they had little to no fluid or were completely black... I filled it up with Traxxas 33% and it fired right up. Stalled once and smoked a bit. Probably all the oil and lub stuff from the rebuild. Hit it again and it purred like and angry tiger... (nice deep growl). I will finish breaking it in it today, but feel great about my rebuild, all though it cost me 1/2 of a new truck. LOL. Here are some pics of the process. Have new lid on order, but it should look like a brand new truck when completed.















    All done... Time from break in.

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