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  1. #1
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    my flywheel is loose on trx 3.3

    Does it mean I need a new engine or is there a way to fix it?

  2. #2
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    Take off your Clutchbell and try to tighten your flywheel nut

  3. #3
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    im talking about the engine silver flywheel- the person at my LHS said i need a new engine, but i am wondering if there is an alternative. They said that when the aluminum heated up, the engine lost too much compression and cuts off.(that is why i took it in, b/c it shut off)

    So now i have an almost worthless car, but I can still drag race for 2-3 minutes at a time

  4. #4
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    If your engine flywheel is loose try taking out your engine take off the cb and take off the clutch. There should be a small nut
    I between the clutch posts. Try tightening it

  5. #5
    Marshal Double G's Avatar
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    The flywheel has nothing to do with the compression of the engine. What the LHS is talking about is the cylinder and piston. The cylinder is tapered so that as the piston drives up it compression is built. After abuse or a bit of wear that sleeve will lose its taper and not be able to hold compression. So when it warms up the engine will shut off only to restart when cool.
    The Super Derecho

  6. #6
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    So is there any way to fix it without a new engine?

  7. #7
    Marshal Double G's Avatar
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    You could get it repinched through Ray A Racing (Google search) or buy a new piston and sleeve.
    The Super Derecho

  8. #8
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    Would that for sure fix it permanently (as in as long as a new engine would last)?

  9. #9
    RC Turnbuckle Jr. Snook Man's Avatar
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    That would depend on the condition of the rest of the engine internals (bearings, connecting rod, crank shaft).
    If you’re not experienced with nitro engines and know what to look for as far as if a rebuild is cost effective, I would recommend a new mill.
    No slipper/tall gearing/power = broken parts.

  10. #10
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    What is a mill?

  11. #11
    RC Turnbuckle Jr. Snook Man's Avatar
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    Mill = engine.
    No slipper/tall gearing/power = broken parts.

  12. #12
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    oh- so a resize or new pistion/sleeve should fix it so the compression is back to normal. The person at my LHS said the whole engine was messed up so the compression is bad.

  13. #13
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    Its good to listen to information from a hobby shop & other places but don't believe everything your told, in saying that though, some hobby shops & other people are really good and honest & know what their talking about. Shops do have to make money though & some will tell you that you need new stuff just to make money & sell stuff. I just had this experience myself with nitro fuel, I just don't believe everything I hear though & like to do a bit of research before spending the dollars. Has saved me a bit of money & shown me where not to shop.
    REVO 21tm grunt & JQ Products "The Car" GO NITRO

  14. #14
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    i am still debating- If i get a new engone, im going to tune the old one for max performance and drag race it for a few days. first

  15. #15
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    what should i look for inside to tell if it makes sense to sent it in for resizing?

  16. #16
    RC Turnbuckle Jr. mike-susieq1's Avatar
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    make sure its not broken or chipped or pitted in any area of the piston or sleeve. any small chips in the piston will not be able to resize it or even cracks.
    DEU 8:18 ESV

  17. #17
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    i just took apart my engine. piston and sleeve look fine, but the crankshaft and one-way bearing are rusty. I need to go look at the piston and rod again though. is it worth getting a new shaft and bearing?

  18. #18
    RC Turnbuckle Jr. Nitronaught's Avatar
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    Quote Originally Posted by Icero1 View Post
    i just took apart my engine. piston and sleeve look fine, but the crankshaft and one-way bearing are rusty. I need to go look at the piston and rod again though. is it worth getting a new shaft and bearing?
    If you can push the piston past the point of the sleeve with you hands then the piston and sleeve need replacing.

    To check the conrod, put it onto the crankshaft and put 1 drop of light oil (3 in 1 household oil is fine). Byt working the crnka back and forth with resistance on the conrod the oil should not push out of the connecting point to the conrod from the crank. If it does, your conrod needs replacing as well.

    Piston + sleeve + conrod on Ebay goes for about $60.00
    Engine bearings about $35.00 for good ones..
    Head shims $10.00 if necessary (see any leaks from the seam of the cooling head replace the head shim if not use the old one).

    Now for around $105.00 you can get a new 3.3 pulled from a new truck on Ebay. So there are options...


    That's $95.00 plus any shipping and then there's your labor
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  19. #19
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    Piston and sleeve are fine then b/c I can't push them out (in fact i got them stuck). I think conrod is good, but will check that out more later. Could it be that I lost compression when the engine heated b/c of the rusty bearings/ crankshaft? If I decide to fix it, id get new shims too...

  20. #20
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    what size are the bearings, i just started looking?

  21. #21
    RC Turnbuckle Jr. Wildman4910's Avatar
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    7x17x5mm Front
    http://avidrc.com/product/16/engine-...-bearings.html
    http://avidrc.com/product/16/engine-...-bearings.html
    12x21x5mm Rear
    http://avidrc.com/product/16/engine-...-bearings.html
    http://avidrc.com/product/16/engine-...-bearings.html

    Nothing against your LHS but they are there to try to sell you parts, and I've seen enough that will say 90 times out of 100 tell you its trashed you need a new one, like the one in the glass case here!

    If your engine parts are in good shape rebuild/repinch it, if they are cracked, chipped, deeply scratched/gouged, badly pitted then save yourself the trouble & get a new one.
    Look out for the tree/crunch!

    LiPo? Naw NITRO!!

  22. #22
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    I can tell now by looking at piston that the previous owner ran way to lean- the piston is halfway blackish, gray color.

    Im going to post a picture later to see what you guys think about the rest of the parts.

  23. #23
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    now that i look at bearings- not bad enough to replace- getting new backplate and crankshaft if you guys think everything else looks ok.

  24. #24
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    oh, can't post pic without account- Im going to order the parts- one more thing i'm adding is new teflon washers- I'll let you
    guys know how it goes.

  25. #25
    RC Turnbuckle Jr. Nitronaught's Avatar
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    Quote Originally Posted by Icero1 View Post
    I can tell now by looking at piston that the previous owner ran way to lean- the piston is halfway blackish, gray color.

    Im going to post a picture later to see what you guys think about the rest of the parts.
    Here's something to keep in mind. I don't want to put any 'Scare" tactics on this... But, often, when an engine is ran lean, it may not be failing just yet, but the materials of the piston, the sleeve and conrod could already have been damaged by the extreme temperatures that were happening at the time that was causing the black coloring...

    That black, dark brown coloring is called carbonizing. This happens when oil is exposed to such a high temp it burns and leaves carbon deposits in the pores of the metal... At these temps the strength of the metal parts, especially the piston skirt area, become brittle. Only to fail down the road...

    So you may have some damage, you may not. There will be no real way without special equipment to see if the metal internals have lost their temper/strength.... It's a gamble...

    Me, i'd soak it in WD-40, use no abrasives, clean with WD-40 and use light machine oil as your assembly lube or Marvel Mystery Oil (my preference).... Tune it and let her run....

    Worst case is you get your tuning skills down on an engine that may be on the way out anyways... Most people, their first nitro does not last as long as their 2nd or their rebuild due to having to learn how to tune.
    Last edited by Nitronaught; 10-16-2012 at 10:18 AM. Reason: added info.
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  26. #26
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    So, is your flywheel coming loose? Is it possible the aluminum flywheel is worn out from coming loose? Replace it and all should be fine....right?? When my 3.3 flywheel nut came loose, the engine shut off - as expected. I just retorqued the flywheel nut and I still run that engine

    I see several conversations going on but I dont know if his/her issue has been addressed - just saying. Its worth a try...its free to tighten a nut (unless you have to buy the wrench)

  27. #27
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    No, the loose flywheel was a symptom of bad compression. I have ordered parts to attempt fix.

  28. #28
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    Oh, and I also have a used Rustler in the mail, which Im sure will be the next thing I will have questions on...

  29. #29
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    local hobby shop says i need new piston/sleeve- should I resize or replace? They pushed the piston till it was, maybe, .75mm past the sleeve.

  30. #30
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    Yepp it's bad it depends on what u want and are u still learning how to tune or do u think u have it figured out? If your still leaning how t tune IMO you shood just get it resized (ray racing) you can get prolly 2 more gallons out of it but if u know how to tune now u might as well get a new p/s since it will last much longer if kept in its temp range...

  31. #31
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    I would for sure keep it in its temp range- id be extremely happy to get 2 more gallons through it. I also just got a rustler so I will have to split the time, as soon as I figure out there are air bubbles in my new fuel line. One more thing, Im
    not all that great at tuning, b/c I don't have access to a surface heat therm. Im trying right now to keep .18 cvr on rustle
    temp down...

  32. #32
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    piston is in, will rebuild soon, anyone know how to get the bearings back in without damaging them?

  33. #33
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    and what should i use to oil the bearings and other parts- i think light oil?

  34. #34
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    I have finished putting the engine back together. I have a question for thoses of you that have rebuilt an engine before. Is it nessecary to use a new glowplug for break-in, and should i use the heat break-in method or the regular? Either way, Im getting a infared thermometer...

  35. #35
    Marshal Double G's Avatar
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    Best practice is to put a new glow plug in and use the Traxxas method to break-in. It would help to preheat the engine prior to starting too.
    The Super Derecho

  36. #36
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    ok, ill order some glow plugs and a thermometer

  37. #37
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    I got everything together, went to fire up the engine and the ez-start couldn't turn it over. So I had to go charge the battery
    up. Now when I try to start it, it starts but the idle is erratic and very high even after adjustment. So I start to put around
    doing the 1/4 throttle thing for break in. Every minute I would check the temps. For a while they stayed under 200, but then the engine stalled. I checked the temps and it was at 250 F. I put the car up and let it cool. Later in the day, I tested the compression and I couldn't even turn the flywheel with a screwdriver. I was just stripping the metal ridges off of it. So I
    concluded that the compression was still good.

    So here is the question I have. Why is my engine stalling and overheating even when the compression is good and hw do I fix it?

  38. #38
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    anyone have any input?

  39. #39
    RC Turnbuckle Jr. Nitronaught's Avatar
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    Quote Originally Posted by Icero1 View Post
    anyone have any input?
    Break in settings/factory settings normally will have the high speed needle a bit rich,,, BUT the LSN a tad lean... What this does is give you lots of lube and high temps.... 250 is fine... higher than 270 is not....

    COntinue on.... After break in,,, follow this tuning sticky for tuning for performance,,, tune that LSN, use no more than 1/2 a tank and try to tune with the lid on since that's the way it's ran....
    http://traxxas.com/forums/showthread....&goto=newpost
    Founder of H.U.A.
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  40. #40
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    i'll pull it out tomorrow and try, but how do I keep it running?

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