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Thread: 3.3 went kaboom

  1. #1
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    3.3 went kaboom

    only 1gallon of fuel through my 3.3 on my revo and the engine broke the connecting rod. Called traxxas about the engine replacement plan,They said to send it to them and I could get a replacement at 1/2 the price.I asked how much it would be and he said 125.00 dollars. I asked about the half price of the motor would be about 65.00,and he told me the engines retail for 250.00 and the 125.00 is half price. Well I figure it this way, why should I box that up and send it back to them and still pay the hobby store price of 125.00 when I can keep the old engine for all the good parts left on it and of course and just pay the 125.00 for the new one. I think there pulling the wool over peoples eyes,They should put that info in their policy so people know not even to bother with calling or going to them. my engine temp about 20 seconds after the motor blew up was 218 degrees.I have never had this happen before and have owned manny traxxas products and been in this hobby for a long time! I am actually quite dissapointed in them! Buyer beware!

  2. #2
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    Could be a problem ...here's what I did with the exchange program ..I had run about 15 gallons through my 3.3 when the con rod broke..but it cracked the block and broke the crank. I didn't feel like I had much good stuff left in it..so I used the exchange program but it was $110.00...had it running in 30 minutes ..could be wrong but felt as if I came out ok that way...but I can see why you would be better to keep your motor for reasons you stated...good pick with the new motor . Hope it holds up good for you...
    Speed cost money!
    How fast do you want to go ?

  3. #3
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    Con rods seem to be problematic on these. I just snapped mine over the weekend. No sure how much fuel put though it I bought the revo used and it was cheap so can't complain. Just ordered new motor on eBay no carb or flywheel for 98.00 shipped. I just hope it's here by Sat.

  4. #4
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    If the motor only has a gallon on it then why not just buy the Piston,Rod, and sleeve combo off ebay for 65 bucks and only use the con rod for now. Then you'll have a new piston and sleeve sitting in case and its still cheaper than the 125 at your LHS. If it was me that's the route that I'd go.

  5. #5
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    Has there been more reported incidents of the 3.3 rod letting go vs the 2.5 engine? Yes. If you are here on the boards long enough you will see; though the amount of complaints has diminished greatly the past couple years. This "issue" has been brought up many times and the same violin gets played every time with the responses to the point that the threads get shut down. Most of the time it is the issue with the person holding the screwdriver and in the past it has been reported by other members that Traxxas has taken the engine and after inspection has sent a new 3.3 out without charge. Given the amount of 3.3 engines out there, the incidence of this happening is pretty remote and many of us have gallons upon gallons on our engines without rod failures.
    Traxxas' [suggested] retail price of the engine is $250, and that is different than the actual selling price--one place being Tower selling them for $140. You could pick up a new piston/sleeve/rod and rebuild the engine yourself or buy a new engine of eBay and keep the old one for parts.
    There is nothing about buyer beware here. Traxxas is in the business of making profits and apparently a bit of that profit goes right back into customer service. I've been on the good end of CS and do hear that many of the representatives bend over backwards to help out customers. It's all in how you approach them with the matter.
    The Super Derecho

  6. #6
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    It's good to hear that someone else run 15 gallons threw there 3.3. Good tuning revo stevo. I broke a rod about three gallons before it lost compression, but it was my fault for running it too rich. It was helping with control at the track, the Jato is to fast for most tracks. That taught me to just tune it right and lay off the throttle.

  7. #7
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    Quote Originally Posted by Mark Ball View Post
    It's good to hear that someone else run 15 gallons threw there 3.3. Good tuning revo stevo. I broke a rod about three gallons before it lost compression, but it was my fault for running it too rich. It was helping with control at the track, the Jato is to fast for most tracks. That taught me to just tune it right and lay off the throttle.
    I'm not trying to hi jack this thread but, I am confused on why running your 3.3 rich would lead to rod failure. Mark can you elaborate on this a little more for me.
    Thanks
    REVO ROOKIE

  8. #8
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    I think the excess duel builds up pressure in the crank case

    Sent from my SPH-L710 using Tapatalk 2

  9. #9
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    When the combustion chamber gets overloaded it will cause to much compression (pressure). At idle it will vapor lock and just quit running and make you have to unflood it. But at high rpm's it can break parts. On the 3.3 the rod is the weakest link.

  10. #10
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    Basically, ou2mame is correct. Excess air/fuel mixture causes combustion to occur earlier than it should. Our engines are similar to diesel engines in that high compression is required for combustion. If there is excess air/fuel mixture in the combustion chamber, while the piston is on it's way up, combustion occurs too early, and this pressure is trying to push the piston back down. Basically, the pressure is so forcefull, that it wants to reverse the rotation of the engine on every stroke. Even at an idle, it is damaging to the rod.

    We dance a fine line, in this regard. With a perfect tune, combustion occurs just before the piston reaches the top of it's stroke. But, it happens late enough in the upstroke, that momentum allows it to overcome the forces of the piston wanting to be pushed back down.
    Believe 1/2 of what you see,and 0 of what you hear

  11. #11
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    Oomp, Mark Ball, and ou2mame You guys could not have made it any more clear as to how and why this happens and it makes a ton of sense now.
    Thanks for the responses.

  12. #12
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    Glad to be of help.
    Believe 1/2 of what you see,and 0 of what you hear

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