Trucks T Maxx 2.5 starting issues

[Dan01]

Hi,

I this is my first time on the forum and I understand this has probably already been posted about. Any help / links will be greatly appreciated

Ok so I've dug my 2.5 out after a couple years no use. I've completely stripped and rebuilt the engine there's no sign of rust and bearings look and feel fine.

I've reset to factory settings which I believe to be 4 turns out on high speed needle, 1 3/4 turn out on low speed with a .7-1mm gap on idle needle. I also turned the hsn out a bit more due to tuned pipe

Here's the issue
It won't start unless I add throttle, at which point it will run fine until throttle is let off, I also managed to richen it until it changed into second gear whilst holding it up.
I tried driving it around later on to find that it's also revving really high but moving around really slowly.
I've tried turning the piston around to what I now believe to be the correct position, with the small cut out facing towards the carburettor inlet (although on your YouTube video it looked as though you pull it out with the cutout facing the exhaust?)
I'm running 20% fuel

Thanks in advance and sorry if I don't reply much later on as I'm GMT and it's getting near to bed time, however ill look when I'm up in the morning before work!


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[Tony]

For the dying issue, it sounds like your opening is not open enough. Try adding throttle to open the carb (while it's not running) and turning the idle adjustment screw in about a half turn then start it and see if it helps. If not, keep repeating the steps until it does.

You may also need to lean out the low speed needle an hour or two as well. This will also raise your idle rpm, but too lean and you will burn up the engine and/or cause it to flood when you apply throttle.

As for revving up and not moving very fast, take the clutch off and take a look at the clutches. Best case scenario is they are just glazed over and you can take some 120 grit (or any sandpaper really as long as it's over 120 grit) and sand the clutches and inside clutch bell lightly until all glazing is gone. This should cause it to grip better.

However, if you have a driveshaft that is broke or the pin is missing, it will also cause this. Hold 3 of the wheels and spin the 4th. If it spins, you have a problem. Do this for all 4 corners.

Let me know if any of this helps. I'm trying to get my hands on some fuel so I can pull out this 2.5 I have sitting here and so some videos on it.

 

[Dan01]

That makes sense, my idle needle I was turning out rather than in,

See now factory settings says 1,3/4 turns out or flush, but I saw a photo that showed a flush carb earlier which would be around 3 whole turns out? ( stupid question but I'm guessing 1 turn = a full 360 degree rotation.)

Which pin on the driveshaft? The small clip and washer are both on the end, I will add a photo tomorrow when it is lighter outside


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[Dan01]

I've just watched another video which also says the clutch pad should be put back on with the right hand hole on the bottom pad and left hand hole on the top pad which I never knew before and should check


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[Tony]

Yea, don't turn it out, that's not going to end very well lol.

Stock high speed setting is 4 turns out. This is going to be pig rich and almost no power, but it should run if you have a good glow plug (watch my video, my glow plug that was still glowing was my problem. Hours of testing and it was a glow plug).

Stock low speed needle is flush with the inner ring on teh side of the carb. I'm not sure how many turns this is as it's going to change as you open the carb up with the idle adjustment screw. Just set it flush and you should be good.

As for the driveshaft, you have 6 of them on that truck. Two coming from the transmission to each differential, and two coming out of each diff going to each of the wheels. There are 12 pins on these 6 shafts and any of them could be out. Just check them by holding 3 wheels and spinning the 4th to see if you have one broke. Most likely, you don't and it's a clutch issue. Clutch dust can accumulate and actually hold the clutches in and not allow them to grab the clutch bell.

 

[Tony]

I've just watched another video which also says the clutch pad should be put back on with the right hand hole on the bottom pad and left hand hole on the top pad which I never knew before and should check


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If you get the clutches turned around, where the end without a pin is the leading edge, it will cause it to grab really hard. I don't think these have a spring, but I could be wrong. If it doesn't, they will always rub and try to grab. If they do, then this is a setting that could cause damage with grabbing too hard. But, grabbing too hard is not your issue lol. Either way should work for testing, but only if you have springs. If no springs, the end with the pin needs to be the leading edge. Man, I need to get some videos together on this stuff lmao.

 

[Dan01]

Do you know of a good supplier for glow plugs? I know the deal it's best to have two or three on hand and last time I got one they weren't exactly cheap for what they are!
Yep got it I'll make it flush, then maybe try adjustment afterwards.
Driveshafts now I'm getting mixed up with can shafts! Yeah I'm pretty sure they're all fine. When holding it up all four wheels were spinning like mad, I'll double check for pins but I've got a feel I'm gonna have to tear out this engine block again and strip the clutch haha!
I've really appreciated all your help and so quickly as well!! I'll see what I can do after work tomorrow and post some pics, I will get this thing running!

I'll see if I can dig up an old video of it too where I had it out doing donuts in the snow haha.
Thing is so many toys so many people there's gonna be a million different scenarios so it's hard to meet all needs! I'd suggest maybe shorter videos showing less stuff, but more of them maybe? Cutting through a 10+ minute video for the bit you need can be gruelling

Thanks again!


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[Tony]

Glow plugs are definitely not cheap. I purchased two, one for a 2 stroke engine and one for a 4 stroke engine, both in airplanes and I spent about $20 for them. So yeah, they are quite expensive. As for a supplier, I would just go to your LHS. I run OS glow plugs in just about everything I run. They seem to last the longest. I would get a medium temp plug for that truck.

Keep me posted on how it's going and post up if you run into any other issues.