why does my tmaxx overheat and shut down all the time????

cdooley · Post by **cdooley** » Mon Nov 10, 2003 12:39 pm

this is very frustrating. after running for about 5 minnutes it shuts down and wont restart untill it cools off. The engine is a 2.5 stock except for a sirio pipe. it does this no matter what the fuel mixture, lean or rich. I even cut out the windshield but no help. even with the body off it does it. i am running traxxas top fuel 20%. please help. i dont even use it that much any more because of this!

Post by **Winston Cup** » Tue Nov 11, 2003 12:41 am

Well this is always a tough one without hearing the car run. You say it's over heating, but you seem pretty sure the settings, lean or rich aren't making any difference, so that makes it tough because if it's a heat problem, without the body on, then that pretty much just leaves your settings to look at. Fill me in the best you can on the conditions in which you are running it, sand, rock crawling, open and fast etc, and when was the last time you totally cleaned out the carb, including the fuel lines and made sure everything is nice and tight, including the fuel and pressure line. How did it run before you put on that exhaust? What else did you change? I'm not familiar with that brand of exhaust, but you may want to make sure your pressure line off the exhaust is tight and the proper type, in case you changed that as well, and also not too long of lines on either. The fuel line needs to be kept isolated or insulated from any heat source like the head, exhaust etc or the fuel will boil and vaporize causing the same problems. How does it sound when it dies? Give me as much info as possible and we'll figure it out. A pic would be nice too if you have it.

Post by **Winston Cup** » Tue Nov 11, 2003 12:53 am

One more thing. What size motor is that sirio pipe for?

sandman4free1 · Post by **sandman4free1** » Tue Nov 11, 2003 6:13 am

do you have a temp gun? check out http://www.novarcproducts.com/ for the possible solution to overheating. they also have cheap temp guns to help in tuneing. I am with guy on this one need to know the sound when it dies and temp would really help. I run the nova heads on all my engines and they really help.

cdooley · Post by **cdooley** » Tue Nov 11, 2003 9:24 am

when it dies it sounds like it ran out of gas. I have visited the traxxas online message boards (which is where i got the recomendation for the pipe) and i was told the reason it is shutting off is because it is getting so hot that the cylender expands and the engine looses all of its compression.
The pipe is the only mod, and it runs great, lots more power than stock. It was recomended to run it richer with this pipe, wich i am, and still this problem. (had the same issue with the stock pipe)

I havent cleaned all the lines and carb out since the motor is still fairly new, only about half a gallon run through it. I do spray WD-40 in the carb after running it. I also keep the air filter clean.

I usually run it at my house, so its on grass, cement and asphalt. Ambient temps about 75-85 degrees. I have tried to run it fast (better cooling) and slow, no difference. usually after a high speed pass it will die as soon as i get off the throttle.

I think i will try the nova head, ive heard good things about it. But something tells me i shouldnt have to. I might have to take it back to the hobby shop and let them look at it.

sandman4free1 · Post by **sandman4free1** » Tue Nov 11, 2003 3:13 pm

still sounds like you are running on the lean side. the nova head will help tons. I help nova with new ideas and have tested most of the tmaxx parts they have. the other thing to cheak is head clearance remove glow plug and use .0020-.0030 thick solder the rule of thumb is .006 for every 10% nitro so you should have in the range of .0012-.0015..clearance if it's less you need to add a 1mm shim. on second though try this as a last resort. and e mail me for better directions. try to ritchen the top end more and lean the low end needle a touch. tuning is definately a feel thing it took me a year to really get the feel for it.....it's even harder behind a pc

TroyB · Post by **TroyB** » Sun Dec 07, 2003 9:48 pm

How much fuel have you ran through this motor? It maybe time for a rebuild. My brother ran about 8 gallons through his and it had the same heating problem that you are having. He rebuilt the motor and it ran fine after. His rebuilt the motor 2 times and its doing it again. They are fun, but man they are a huge hole in the sand to throw money in.

CrashingSucks · Post by **CrashingSucks** » Mon Dec 08, 2003 12:43 am

did you try to put the stock pipe back on?

snewbank · Post by **snewbank** » Thu Jan 22, 2004 5:43 pm

I'm having a similar problem with mine. I have a T-max 2.5 totally stock. I got it xmas 2002. I could never get te thing running reliably and pretty much gave up.

Here is the symptom. Starts-up fine, runs good for about 5 minutes then starts loosing power. Soon it gets to the point where your giving it full throttle and the engine is just bogging. Only goes about 2 MPH like this. Eventually engine just stalls. If try to start it up right away it usaually wont but let it cool for about 5 minutes and it starts-up fine and runs good for about 5 minutes and the whole cycle repeats itself. I have barely gone through about 0.5 gallons on this car.

I know, your going to say it's running to hot, try to richen it. Prior to getting this car, I have been flying model airplanes for years and I have developed a feel for tuning airplane nitro 2C engines. Same should apply here, right?

I have tried tuning this car a hundred different ways using the recommended procedures and starting positions. I can go so rich the glow plug can barely stay warm by itself and still it will die after 5 minutes. I have read volumes on tuning these engines. I checked the fuel line, fuel cap and exhaust pressure line and could not find any sources for leaks or drop in pressure. I am using the standard Traxxas fuel recomended for this car. I have changed glow plugs. I gave-up. It now gathers dust. Got any ideas? Maybe I have a defective engine but I can't really imgaine what it would be.

EBCMIKE · Post by **EBCMIKE** » Fri Jan 23, 2004 9:54 am

I have the same problem with mine, it has an aftermarket pipe, head and air cleaner.

Only known solution.....Go buy a HPI Savage!

My Tmaxx is one week older than my savage and the Tmaxx just sits now. It is too tempermental and too flimsy. I have beat the hell out of the savage and it takes the abuse and keeps on rolling!

ANyone want a good deal on a hardly used T-maxx?

Post by **Winston Cup** » Sat Jan 24, 2004 12:49 am

EBCMIKE wrote:ANyone want a good deal on a hardly used T-maxx?

Sure Mike how much ya want for it. I can make it run just fine. You can PM me the price if you'd like.

EBCMIKE · Post by **EBCMIKE** » Wed Feb 11, 2004 10:00 am

Well I just wanted to refresh this topic, I found out why mine wont run!

I yanked the motor out and took a look and the sleeve is all gald on the exhaust side. Now I broke it in according to the rules, but I was also not the first one to run it, the kids at the hobby store had played with it in their parking lot and assured me it had already been broken in.

So $80 later for a cierio (?) 5 port sleeve with piston and it is rocking and rolling again.

Still like my Savage best, but that T-Maxx is a lot more responsive.