Traxxas 3.3 problems

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Got Nitro?

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A couple of weeks ago I bought a used 3.3 T-maxx,since then I have never managed to get the engine to run right, I replaced the carb body due to idle jet hole was stripped out thinking that would be the reason that I have had the following issues, idle up/down on its own, WOT without the car opening,etc. I have pulled the engine apart and RTV everything that fixes a normal air leak situation. But I've got no change, once after every so starting cycles it hits a sweet spot and revs up and down like a champ a few seconds later the hope fades away. I checked the piston and sleeve and its been 10 years since I've played with a nitro so I'm unsure if it could be a compression problem. Any input suggestions, engine temp stays between 180-200.
 
A couple of weeks ago I bought a used 3.3 T-maxx,since then I have never managed to get the engine to run right, I replaced the carb body due to idle jet hole was stripped out thinking that would be the reason that I have had the following issues, idle up/down on its own, WOT without the car opening,etc. I have pulled the engine apart and RTV everything that fixes a normal air leak situation. But I've got no change, once after every so starting cycles it hits a sweet spot and revs up and down like a champ a few seconds later the hope fades away. I checked the piston and sleeve and its been 10 years since I've played with a nitro so I'm unsure if it could be a compression problem. Any input suggestions, engine temp stays between 180-200.


Did you check your fuel lines and tank to make sure they have no leaks.
 
I checked the fuel lines and I didn't see a problem, the o ring on the gas tank lid seems fine.

I forgot to mention, when I did get the engine run on its own, it acted like it didn't have enough power to even move itself,engine would reveal to maybe 1/3 and just bog really bad,. I started from factory settings.
 
I had a similar problem with my T Maxx 3.3 a while back. Turned out to be the screw in the fuel tank lid backed off and the O-Ring wasn't sealing right. I just tightened the screw and it ran like new.
 
I checked the fuel lines and I didn't see a problem, the o ring on the gas tank lid seems fine.

I forgot to mention, when I did get the engine run on its own, it acted like it didn't have enough power to even move itself,engine would reveal to maybe 1/3 and just bog really bad,. I started from factory settings.


Your engine temps sound good. My 3.3 runs about 240. I would check to make sure your linkage and servos are acting the way they should. Make sure there's no bidding and battery is fully charged. I would set the engine back to factory settings and see if that helps.
 
Your engine temps sound good. My 3.3 runs about 240. I would check to make sure your linkage and servos are acting the way they should. Make sure there's no bidding and battery is fully charged. I would set the engine back to factory settings and see if that helps.
Checked all that when I had the engine out, it's just weird,I've never had a engine do these kinds of things after all normal steps have been taken to check for running issues and air leaks, the engine at factory settings runs at about 1/4 throttle amount of rev3
 
Checked all that when I had the engine out, it's just weird,I've never had a engine do these kinds of things after all normal steps have been taken to check for running issues and air leaks, the engine at factory settings runs at about 1/4 throttle amount of rev3


Since the truck is used. Would you happen to have a spare engine laying around? If you do I would swap motors to see if the motor acts the same on the truck.
 
I do not have a spare engine yet, I'm gonna quadruple check everything that has been checked, sealed, replaced, including the fuel tank lid, I've had fuel tank lids lose seal but never cause this problem. I'll update tomorrow. Thanks for the suggestions and tips guys.
 
Hi Got Nitro. It may still be the carb. I may have a spare Traxxas carb laying around. I'll have to double check. If I have it still and if you're interested I'll send it to you if you pay for shipping. Of course I'll have to test it first as well so we don't end up with another bad carb. Also I would check the front bearings on the motor. An air leak is not easy to detect on those things. Buku has a cap for the front bearings that's supposed to seal air leaks. They may have one for the TRX 3.3. I wanted to get one for my OS 21TM but apparently they don't fit. I would check that out.
 
It does sound like an air leak issue. You may want to pull the needles out of the carb and just have a quick look at the orings. They aren't hard to mess up. Be sure to use a lube in reassembly as well. Associate's green slime is what everyone likes to use in there but even some vasoline is better than nothing. Just be sure what you use won't eat up the orings when you put it back together. Another common and easily overlooked leak spot is the carbs pinch bolt. Make sure it is right but not overly so. You can seal the carb neck as well.
 
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My first experience with AE green slime was when I had my Team Associated NTC3 and TC4. Really great stuff and you can use it with a vareity of stuff it was not originally intended for. I've had it since and still keep one in my tool box.
It does sound like an air leak issue. You may want to pull the needles out of the carb and just have a quick look at the orings. They aren't hard to mess up. Be sure to use a line in reassembly as well. Associate's green slime is what everyone likes to use in there but even some vasoline is better than nothing. Just be sure what you use won't eat up the orings when you put it back together. Another common and easily overlooked leak spot is the carbs pinch bolt. Make sure it is right but not overly so. You can seal the carb neck as well.
 
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It does sound like an air leak issue. You may want to pull the needles out of the carb and just have a quick look at the orings. They aren't hard to mess up. Be sure to use a lube in reassembly as well. Associate's green slime is what everyone likes to use in there but even some vasoline is better than nothing. Just be sure what you use won't eat up the orings when you put it back together. Another common and easily overlooked leak spot is the carbs pinch bolt. Make sure it is right but not overly so. You can seal the carb neck as well.


When i assembled the new carb I replaced all the o-rings,however it never crossed my mind to lube the carb up during assembly, I've tore many carbs down but I have never lubed one, I did check the gas tank, the owner prior just replaced the lid and it seals perfectly, for some reason the owner prior ran almost a foot of fuel line coming from the tank to the inlet on the carb, I've never done that but I'm assuming theirs a point that it's just too long,I'm gonna shorten the fuel line tomorrow and get a can of break clean and check for external air leaks, I did not seal the pinch bolt or carb neck with RTV, so if theirs a leak I've only got 3 more places to check.

Hi Got Nitro. It may still be the carb. I may have a spare Traxxas carb laying around. I'll have to double check. If I have it still and if you're interested I'll send it to you if you pay for shipping. Of course I'll have to test it first as well so we don't end up with another bad carb. Also I would check the front bearings on the motor. An air leak is not easy to detect on those things. Buku has a cap for the front bearings that's supposed to seal air leaks. They may have one for the TRX 3.3. I wanted to get one for my OS 21TM but apparently they don't fit. I would check that out.


Right now I'm going to try and make this card work since its brand new,i do appreciate the offer thank you.
 
IMG_0539.JPG
The offer still stands should you need the carb. I'm always up to helping any member any way I can. Also you can choose to upgrade to the Losi carb. I heard the TRX 3.3 is a screamer with this carb and it's way easier to tune and holds the tune very well. You can probably find one on EBay or RB Mods sells em as well and is in stock.
 
I just tried then controversial submerg engine in water test and it has a very minor front seal leak, the front seal never seals 100%. I'm gonna guess that the problem has nothing to do with an air leak, more that it probably needs a piston/sleeve,ots pretty easy to rotate over that a toddler could cycle this engine,.
 
The 3.3 piston sleeve set is not too expensive. RB Mods sells the HD conrods. They also carry a turbo head conversion and a cnc milled aftermarket cooling head. If u want to sink in some serious $ you can get the whole 3.7 conversion done or the full motor.
 
I think I'm gonna step up to a big block, I have found several big block options for the price of a new 3.3. Just not sure what route I want to go. I have never had great luck with Traxxas engines.
 
Funny thing is I've had numerous issues with the 3.3 motor I got that came from my 3.3 Tmaxx from EBay. Must be the reason why the original owner had the OS 22TM mill installed in it. My 2.5 had been a champ though. It's been very reliable and can lift the front tires when u get on it. It's not enough to make it wheelie but I haven't messed with the gearing on the other TMaxx. I know a lot of big block guys out there uses .26 and even .28s but I really prefer a really good .21. It's very smooth through a broad powerband and has more than enough torque. I would start with a .21 since with the bigger blocks you will have to upgrade the tranny and upgrade to 1/8 scale diffs.
 
If it's that easy to turn, I'd say that the compression is your issue. If you don't want to do the work or spend a lot for a .21 you can always use the traxxas engine exchange program that they offer. It may be your cheapest route.
I have heard lots of different stories. In my case, both of my 3.3's have served me well and continue to.
 
I haven't really bothered doing any investigating on the 3.3 mill I got since I still have a spare is 21tm for my sons truck. I also noticed there's an extra Traxxas carb in the packaging when I got the 3.3 TMaxx. I think the previous owners were already having an issue with it already. I'm thinking I'm going to go ahead and buy the Losi Carb and see how it does. If that doesn't solve the issue I'll just get a brand new 3.3 and use the Losi Carb on it. I have plans for my spare OS 21TM. I'm gonna tear down the whole motor, soak it to free up any gummed up bearings and soak the carb as well. Once dry I'll layer some after run oil on the whole thing, dry it out and put the motor away for storage without rebuilding it. This way I'll be sure it won't gum up and rust. The mill will end up on another project later.
 
I'd like to know how the Lodi carb works out.
I mentioned the traxxas engine exchange because lots of ppl don't know about it or have forgotten it. It seems like a realistic option for you and for @Got Nitro?
 

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