Can't Keep 2.5 cool

[BurnData0]

I am having a hard time keeping my T-maxx 2.5 cool. I am running Wildcat Plus 20% nitro, 18% oil. I have cut out the front and rear windows. I am using an MC-9 plug (I called Traxxas and this is what they recomended). I live in florida, the humidity is regularly above 80% and gets up to 100% quite often. Well to get the truck to run below 300-320 deg I have to run so rich that I get VERY poor performance and the truck bogs and stalls constantly. Any ideas other than putting a new head on it (that is my plan but no $ right now). I think I have tried every combination of needle settings that exists. Does anyone else have problems with the humidity.

 

[RaCinJason399]

Not really the humidity.... It could be with ur needel adjustments.. check the low end.. that being off can change alot. Try runing without the body.. see what the temp is... and if its a big change in temp.. then the motor isnt geting enough air... to cool it.

 

[BurnData0]

The engine only runs a few degrees cooler with the body off, still well over 300. The humidity is the only factor I can find to blame for the poor performance. As humidity increases it replaces good fuel/air in the mixture causing a lack in performance so the carb must be leaned out to compensate therefore raising the temp of the engine. I have returned to factory settings many times. The truck runs like a champ there but gets very hot. I have to run at about 5 1/2 turns out on the high end just to keep it under 280 and I am running the lowend as rich as I can with out stalling. If I lean out the low to compensate the performance gets better but the temp goes back up. And I have taken the carb completely apart and cleaned it and checked for air leaks or bad seals with no luck.

 

[Rob D]

What about the crankcase you say youve checked the carb what about backplate and the bushing/bearings where the crank goes though and the front where the shaft for easystart goes though ..

how about checking tank for air leaks replacing your fuel lines

 

[FLATTOP]

Burndata, I am having the same problem with my 2.5, mine runs at a consistent 300 degrees but I also run the piss out of it.

I have no performance issues at those temps, runs like a top but I know engine life is suffering, I am going to continue to run mine and hope I can get atleast 2 gallons out of it.

I will have 2 new ones coming as soon as the engines become available.

I have heard elsewhere that others are having heat problems in the 300 degree range also and then I have seen others who never get over 200 degrees. Humidity and altitude play a big part in tuning and performance, I don't have the humidity you have but am getting close.

Use this statement at your own risk........I would say not to tune for temp but for performance, tune it for the sweet spot, by that I mean a nice smooth idle, good punch off idle, good top end and just check the temp for reference, then go and have fun.

Keep your air filter clean, I clean mine after every run, make sure you have plenty of air flow, I cut out my front and back windows.

 

[x_789]

The filter is definatly something to check a buddy runs a 2.5 and he changed from the TRX filter to a good dual element filter like this http://www.dynamiterc.com/Products/Detail.aspx?ProductID=DYN2614 I prefere these many times over the motor saver filters because of the prefilter. You will get much greater air flow not to mention keeping the prefitler dry you will not get the cloging issues as with the stock trx filter.... a couple buddies where able to fatten up their engines a good amount with the larger air filter due to more airflow.... X

 

[HumboldtBlazer]

Originally posted by BurnData0
I am having a hard time keeping my T-maxx 2.5 cool. I am running Wildcat Plus 20% nitro, 18% oil. I have cut out the front and rear windows. I am using an MC-9 plug (I called Traxxas and this is what they recomended). I live in florida, the humidity is regularly above 80% and gets up to 100% quite often. Well to get the truck to run below 300-320 deg I have to run so rich that I get VERY poor performance and the truck bogs and stalls constantly. Any ideas other than putting a new head on it (that is my plan but no $ right now). I think I have tried every combination of needle settings that exists. Does anyone else have problems with the humidity.

Just my take from what I understand. If you are using the MC9(cold) plug that is for 25% nitro and the MC59(hot) is for 20% nitro. If you understand the difference in nitro % and how it burns then you will understand that the hotter plug works better than a colder plug with the less nitro content. I think this might be your problem so if you have a hot long plug doesn't have to be McCoy it should make the engine temps normal. I live in a humid climate (more rain humidity that the florida sticky humidity) and the McCoy MC59 works great in my T-Maxx 2.5. Also engine air leaks are a big overheater problem causer. Check fuel lines and see if the head is tight. The most likely place for air leaks on the 2.5 is the carb so make sure its tight and the seals are in good condition

 

[M@xximillion]

I run top fuel 10% with a MC59, temps stay within 240 to 270.
I have never burt out a glow plug either, The temps have been pretty cold and dry here. I am curious to see how it performs in the summer climate.

 

[Blakedude409]

thats wierd, no matter how hard i try i can't get the temp over 220 and i use odonnel 20% with the traxxas long plug.

 

[nitrojunkie]

Just to confuse issues I have melted many hot and medium hot plugs with my rustler 2.5. I richened the LSN which helped but still melted plugs. I now use a cold plug. Mc9. this keeps my engine running cool.
I shal explain and this is hyperthetical guess work.
a cold plug retards the engine a little the fuel fills the cylinder and cools it a little before ignition. ignition slower with a cool plug. a hot plug would ignite the fuel quicker = hotter although performance would be better. Tmaxx is heavier than my rusty so performance difference mybe more noticable. but i run real cool now...
I also put the long tube mod on my exhaust to fuel tank. and now it doesn't cut out or stall.

 

[SilentHunterKellen]

This must be the 100th thread about this topic....I'm having the same problem! I'm just gonna get a new head. I found a good looking one.
[move]-Kellen[/move]

 

[nitrojunkie]

add some of this too cool it down. often works a treat.

http://www.nitroblast.com/nb12.htm

or a similar product.. but make sure its for nitro caster fuels not for normal petrol cars as they wont work.

 

[HumboldtBlazer]

You guys have an air leak, using the wrong plug/fuel or dont have it tuned right period. My T-maxx runs 250-260 and at its hottest 270 with McCoy MC59 and BT or MH fuels. I use the stock head and carb.

 

[Çh®i§tiªñ]

I would pull ALL the needle assemblies out and make sure your O-rings are good too. Just another possibility.

 

[FastEddy]

I was having a bit of a heating / bogging issue yesterday.
I changed to a Mc Coy 59 plug from an OS0-8 re-tuned and Wa-La...
It may be worth a try.

Changing to the 59 made my settings fatter.

Engines are like women. Some days you can never get it right no matter how hard you try. 8-0

 

[SilentHunterKellen]

Truer words were never spoken...
[move]-Kellen[/move]

 

[[email protected]]

I have 2 tmaxxes 1 runs normal temps of 170 degrees over the outside air temperature, which is your basis for measuring how hot engine "should" run. needle settings anywhere from 4 turns to 5 1/2 turns hsn. the other tmaxx is crazy it runs at 2 1/2 turns on the hsn, and runs hot. my local hobbystore owner who is a traxxas trx 2.5 guru, and i have exhausted all possible engine, exhaust, and fuel system problems that would cause this, at no avail, i must add. even contacted traxxas, response being the engine will run how it wants too, rich or lean, hot or cold. you should not have to buy aftermarket parts for your 2.5 too make it run like it was designed to from factory, unless you are looking to enhance performance. does not sound like you have any air leaks , if you did the engine would want more and more fuel, and that does not sound like what you are describing. if anything your engine is over compressing, not much you can do there,but lean it out and run hot.as long as engine is not overheating and shutting off you are ok. just take notes on everything you do and keep in touch with manufacturer, if engine goes they should back you up on it. good luck.

 

[russgunn]

I was also having major temp probs with my 2.5 until I bought the Motor Saver filter for this engine. Due to it's higher airflow I was able to richen up a touch and temps dropped from a regular 340F to around 260F instantly. IMHO the stock TRX2.5 air filter chokes the engine.

 

[nitrojunkie]

i cut the gause off my stock 2.5 air filter. now i can pull it out easily to clean it. I did however over oil it one day and that choked it too. now i hardly use any oil. think i may go with motor saver too. got one on my 8 port savage, didnt think the 2.5 .15 would need that much air but guess i was wrong.

 

[HumboldtBlazer]

Originally posted by [email protected]
I have 2 tmaxxes 1 runs normal temps of 170 degrees over the outside air temperature, which is your basis for measuring how hot engine "should" run. needle settings anywhere from 4 turns to 5 1/2 turns hsn. the other tmaxx is crazy it runs at 2 1/2 turns on the hsn, and runs hot. my local hobbystore owner who is a traxxas trx 2.5 guru, and i have exhausted all possible engine, exhaust, and fuel system problems that would cause this, at no avail, i must add. even contacted traxxas, response being the engine will run how it wants too, rich or lean, hot or cold. you should not have to buy aftermarket parts for your 2.5 too make it run like it was designed to from factory, unless you are looking to enhance performance. does not sound like you have any air leaks , if you did the engine would want more and more fuel, and that does not sound like what you are describing. if anything your engine is over compressing, not much you can do there,but lean it out and run hot.as long as engine is not overheating and shutting off you are ok. just take notes on everything you do and keep in touch with manufacturer, if engine goes they should back you up on it. good luck.

It sounds like the second Maxx that is running way lean and hot need to have the carb taken out and sent to Traxxas if you and you LHS owner have exhuasted all other possibilities. It is known that some of the composite carbs were defective from the get go. Traxxas will not admit it publicly but I'm sure if you send it to them (the carb) the will replace it since their cust service is probably one of the best in the industry.