25jon25

hey guys i have a tmaxx with a trx 2.5 and when I'm driving it everything is normal for about 5 minutes then it wont idle it just dies i know its not a tunning problem because i tune it and it doesn't help so i just had it tunned by the Lhs [he really knows what hes doing] and it still happens i don't think its a compression issue because it still has enough power to do wheelies
i think i might just buy a new motor because i just finished my 5th gallon of fuel lol
or buy a revo when the come in

sorry if it seems like a rookie Q I'm quite new to the hobby


thanks jon

Troublesome2g4

It only does it when you let it idle down? If so I would say get some new clutch shoes and springs. As the springs wear out they make it easier for the shoes to engage the bell at a lower RPM, where the motor might not have enough torque to keep itself running while loaded...Start with that...

25jon25

ok thanks any other suggestions

R/C Madman

My Feedback: (1)

With 5 gallons through it I would say it is close to it's useful life span. I am not saying you can't get more out of one but, most are done by then unless you took exceptional care of it.

rdmonster

I hate to say it but ...glow plug? I'm sure you thought of it but you never know.

Razoo

My Feedback: (2)

I had the same problem with mine with over 7 gallons thru it. Its all packaged and ready to be sent back to Traxxas with my $105.00 for a new one. Anytime you get 5 or more gallons thru an engine you've got your moneys worth out of it. While your waiting for the new one do what Troublesome suggests and replace the clutch shoes, spring, clutch bell and the 2 clutch bell bearings and you should be good to go for another 5 gallons.

strtsmt18

My Feedback: (-1)

yea all good, mine was cared for excepinally and at about 5 gallons it was time for a new one (engine) i think comes down to how much and how hard you drive it

BIG BOYZ TOYZ

DON'T WASTE YOUR TIME !!!!!!
TRX 2.5 IS A VERY FAST ENGINE BUT IT WILL NOT HOLD IDLE EVEN AFTER THE RUN IN .
I OWN A T-MAXX AND I'VE CHANGED 3 ENGINES ALL OF THEM HAVE THE SAME PROBLEM.
FORGET IT !!!!
DO NOT WASTE YOUR TIME TUNING .
SWITCH TO A SIRIO 18 OR PICCO 21 MEDIUM BLOCK. OR IF YOU CAN PAY MORE SWITCH TO A XTM CONV. WITH 24.7.

SORRY TO UPSET YOU BUT THIS IS THE FACT

BIG BOYZ TOYZ

DON'T WASTE YOUR TIME !!!!!!
TRX 2.5 IS A VERY FAST ENGINE BUT IT WILL NOT HOLD IDLE EVEN AFTER THE RUN IN .
I OWN A T-MAXX AND I'VE CHANGED 3 ENGINES ALL OF THEM HAVE THE SAME PROBLEM.
FORGET IT !!!!
DO NOT WASTE YOUR TIME TUNING .
SWITCH TO A SIRIO 18 OR PICCO 21 MEDIUM BLOCK. OR IF YOU CAN PAY MORE SWITCH TO A XTM CONV. WITH 24.7.

SORRY TO UPSET YOU BUT THIS IS THE FACT

nitroman99

i have the trx 2.5 engine and cannot keep a idle nomatter what, when i get it running right and not overheating it just dies, is this a common problem with this motor.

lstman

my old maxx did the same stuff your all talkung about. i bought a aftermarket cooling head and it ran alot better. the idling thing was the backplate screws loose. that and it is a traxxas engine. there picky little buggers. probebly why i sold it. oh, make sure the carb is in the engine tight. mine would sometimes loosen that bolt that clamped the carb to the engine.

Stevecut

Yep listen to what they are saying I totally agree the TRX2.5 never gave me a chance to refuel with the engine idling it always cut out, Geez it frustrated me. Now I have the OS cvr .18 and I have time to take a wee, a coffee and refuel and what's more it cools down while idling unlike the TRX.

lstman

lmao. aint it the truth. couldnt even get a swig of the beer before it stalled.

oatmealman

My Feedback: (1)

lol,lmao,i lovemy duratrax torq 16 8 gallons thru here and still running storng granted in the next 2-3 gallons it probably gonna need a rebuild and some other stuff

Frost_

My Feedback: (1)

relevance?

lstman

[&:] lol

fhm101

If the 2.5 in question is in a T Maxx, the good news is the problem is the fuel tank. The bad news is, it's not a fixable problem as long as you run the stock tank and stock 2.5 carb. The combination of tank shape and pressure demands from the stock carb will never allow it to work right once the fuel level falls below the narrow top portion of the tank. You can run a different pipe that delivers more tank pressure, but your 2.5 will still run hot when the fuel level falls even if it does idle. The two most effective fixes are either an OS carb or a shorter, wider fuel tank. The carb fix is simplest and is nothing more than a quick swap and retuning, but it's also expensive unless you can find a low cost used OS carb. The tank fix is much cheaper, but involves moving things around on your chassis to make room for the new tank.

ThermalRD

Well there you have it, those are the FACTS! lol. Go easy on the caps man. Both 2.5 engines i have run and idle exceptionally well. I'll admit the 2.5 is picky to tune. Once you get it, its gold. The 2.5R is alot nicer, and never gives me any problems. Just be patient tuning, and you'll get it. Sounds like big boy has 3 engines he doesnt know how to tune.

Stevecut

C'mon ThermalRD (is that really you in the picture?) you know that the TRX2.5 is a pain. You're just one of the lucky ones that has one that can idle for more than a few seconds. Why of all the engines it's just the TRX2.5 that has so many tuning issues. Yes, the tank contributes to the problems, does it mean I'm a tuning genius when I started the OS CVR .18 the first time and it idled for ever? Guess not, it's just a better engine to keep a tune and coincidentally I am no more a genius because the OS doesn't overheat with the standard T-maxx tank.

ZondaC12

gotta add in my .02, i also have an o.s. .18 cv-rx(s) in my sportmaxx, first 2.5 was beatiful, second one was an absloute pain so i got this o.s. is has not stalled once (well during break in it did a couple times because it has to be so friggin rich). but other than that the thing will idle forever if you want it to. great power, havent changed either mixture screw in weeks, only thing is since i got it it leaks all over the crankcase with fuel, kinda lived with it but dirt got on the fuel and mudpies were all over my chassis near the engine. so ive cleaned it all up and spent 1/2 and hour examining everything throroughly and its gotta be the o-ring that goes under the carb, between it and the intake port on the crankcase, so i sent o.s. a LONG and DESCRIPTIVE email lol and they replied in less than a friggin day and asked for my address to send me a new gasket cuz they believed it was the gasket. so no biggie, i can understand if stuffs defective, its a very new engine, just came out, so my vote: kick-ass engine!

lstman

i heard of that tank prob being what was causing the engine idle failure. i tried at least 4 different tanks from friends buggies. just sitting on the frame while running. savage,mammoth, and 2 1/8 buggies. made no difference for me. what did was the cooling head keeping the temps way down. ran great. but still a traxxas engine. and a small block. had to go. i could have gone with the big block drop in option, but the running gear on it wasnt even strong enough for me with the 2.5. damn plastic gears!

Kemo

I cant wait for the Rossi 2.5 engine sleeve/piston upgrade... hopefully that attracts customers for me because right now... there is a bonus i get for this month and saves that person money too .

motionmachine

So you cant tune it, then its gotta be a POS?
If you cant tune and/or troubleshoot the trx 2.5, TRY AGAIN.
Its one of the EASIEST motors I've ever had the pleasure of tuning, what makes people think that by buying another engine, all the tuning PROBLEMS will simply go away?
HELLO, your still stuck with the same inexperienced mechanic thats likely to scrap (burn't up, blown up) yet another perfectly good engine before aquiring the neccessary tuning/troubleshooting skills.

Stevecut

You must be one of about three in the real world.

Head-n-1/2

I solved all the problems listed here on my 2.5. 1st remove engine from truck, 2nd lay it on concrete, 3rd smash engine with largest hammer available, then go buy sirio .18. Problems solved