Traxxas T-Maxx 2.5 vs 3.3

[jcstraxxas]

I got 2 Tmax's in a trade. how do I tell if they are 2.5 or 3.3?

 

[hotrodrob]

The 3.3 has a bigger cooling head, as for the truck itself the 3.3 should have the revo spec driveline,..post some pics so we can get further

 

[Snook Man]

Well the engine would have the size on the block. Chassis wise, its a good bet if the transmission is grey its a 3.3 model. If its black its most likely a 2.5 model but there are many Maxx's out there that have been modified/converted with parts from one model to another its best if you take some clear pics of the top and under side and post them up for positive ID's.

 

[jcstraxxas]

Well that was simple enough. right on the side of the case after you remove a couple of layers of dirt. Thanks. I got a 2.5 and a 3.3 and two gray transmissions. It was fun yesterday straightening out all of the "miss assembly" of the previous owner. Now if I can just quit running through glow plugs every 60 seconds. Hopefully I got an off brand from the hobby shop by mistake. again thanks. this forum is saving me a lot of time and research.

 

[Nitrotrout]

If you're burning up glow plugs you're too lean, if your plugs are saturated you're too rich.
http://traxxas.com/support/Factory-Carburetor-Settings-TRX-25-25R-and-33
http://traxxas.com/sites/default/files/TRX-Engines_Manual_130103.pdf

 

[1mtx1]

If you're burning up glow plugs you're too lean, if your plugs are saturated you're too rich.
http://traxxas.com/support/Factory-Carburetor-Settings-TRX-25-25R-and-33
http://traxxas.com/sites/default/files/TRX-Engines_Manual_130103.pdf

I like to really base a lot of my tune on the glow plug. I had a guy that lived and died by his temp gun. I pulled his plug and even though it was in the right heat range it was to lean. I showed him my plug not soaked but not burning up and i got him to understand looking at a glow plug is over looked . Imo checking your glow plug is the biggest over looked thing by any new nitro user. It can cause starting issues/running issue and it can tell you if your are lean/rich or just right.

 

[jcstraxxas]

i measured the glow plug voltage from the EZ start at 1.9 volts. The hobby shop guy suggested that the voltage should be 1.2 -1.5. Could this be the root of the problem? Seems that i'm getting only one or two short runs from a plug. I went through three plugs with less than 5 minutes of total run time.

 

[Nitrotrout]

What sort of glow plug igniter are you using?

 

[Snook Man]

i measured the glow plug voltage from the EZ start at 1.9 volts. The hobby shop guy suggested that the voltage should be 1.2 -1.5. Could this be the root of the problem? Seems that i'm getting only one or two short runs from a plug. I went through three plugs with less than 5 minutes of total run time.

Probably not the issue. Too much voltage to the plug usually results in a popped coil instantly.
Most common cause of burning up glow plugs that quickly are 1: Too lean, 2: Debris in the combustion chamber.
It’s almost impossible to foul a plug that quickly from being too rich.

 

[1mtx1]

i measured the glow plug voltage from the EZ start at 1.9 volts. The hobby shop guy suggested that the voltage should be 1.2 -1.5. Could this be the root of the problem? Seems that i'm getting only one or two short runs from a plug. I went through three plugs with less than 5 minutes of total run time.

This is what i would do, right when you have your issue. Pull the plug, look at it. if it is wet you are really rich and failing the plug. If it looks burnt or there is no more wire on the bottom you are lean . Now if there is not a lot of fuel/oil on the plug or there is no burnt marks on the bottom of the plug it could be a leak, i would look at how the truck is driving and if this issue happens over 200 deg . With out being there with you i would think you are to rich or to lean. Or you have a leak or you could have some bad plugs. To be honest i have got top of the line stuff and cheap stuff right now i got a few that are meant for those redcat rtr they sell. I got the hot plug and it works just fine. Shines bright works right and was 3.50 per plug.

---------- Post added at 12:11 PM ---------- Previous post was at 12:06 PM ----------

Probably not the issue. Too much voltage to the plug usually results in a popped coil instantly.
Most common cause of burning up glow plugs that quickly are 1: Too lean, 2: Debris in the combustion chamber.
It’s almost impossible to foul a plug that quickly from being too rich.

Man my buddy had 1/8 buggy and he ran rich after i told him was running to lean. He put in a new plug we tuned it he goes home. I see him at work we run in the parking lot and he told me he went a tad more on the rich side. He went threw the plug. We had a 15 min left on our lunch brake i gave him a new in package plug, and that went in 8 min. I looked it over and he did a half of a full turn on the rich side. I think the op does not know what plug's he is buying as they could be selling him some bs plugs that are not numbered or anything . I understand most people think lean is the worst thing you can do to your motor. I have to tell ya running wayyyy to rich can be bad as well. Starting issue, driving issues, not having full speed, no second gear and if you agree or not glow plugs can fail. I seen it first hand, i know threw brake in i have gone threw a few. I have broke in a lot of engines and to be honest not everyone of them fail after brake . I have a new rtr that should be here but i did grab a hand full of new plugs.

 

[jcstraxxas]

pulled 4 plugs within a minute or two of failure and all looked like they were dry and the coils were physically damaged, i.e., the coil distorted or crammed into the socket. gonna pull the head and make sure that there is no dirt. Running about 4.75 turns out on the HSN. Maybe the carb needs a cleaning and that is causing it to run lean despite the 4.75 turns. Appreciate everyone's contribution. thanks. Where do i find these $3.50 plugs???