T Maxx 2.5 engine issues

[SpeedRacerRx]

Hi all,

Returning back to the rc world after a 12 year hiatus. Growing up I had gas and electric planes, cars and boats.

I took my 12 year old TMaxx out yesterday to introduce my 2 year old son to the world of rc.
Purchased some fresh fuel from the hobby store and attempted to start the 2.5 up. When I originally purchased this I converted it from electric start to pull start. The engine was maintained during storage (a few drops of oil in the glow head and carb). Anyway, after a few pulls yesterday it started up and engine set to 4 turns open on the carb mixture setting. The engine ran for about minute the died out (while I was attempting to adjust) I tried to start it again and the pull start cord would not recoil back into the starter. Took a ride to the local hobby store (assumed I needed a new pull start) took apart the necessary parts to gain engine access and installed the new pully and gave it a few pulls to test. Same issue issue, will not recoil back unless I manually turn the clutch. Anyone have insight as to what might be wrong?

 

[D3MON]

when you loosen the screws that hold the pull start housing, does the pull start recoil then? one thing that can happen is if the housing is tightened to much it can deform the plastic slightly, and pinch the assembly, usually loosening the screws 1 to 1/2 turn can help it recoil.
if even completely off the truck, it is still not recoiling, there could be an issue with the spring, or might have just popped out of the slot.
pull starts are pretty cheap, so you may elect to get a new one altogether, i do recommend practicing with the old one on rebuilding them. PITA at first, but gets easy after a few times.

 

[SpeedRacerRx]

when you loosen the screws that hold the pull start housing, does the pull start recoil then? one thing that can happen is if the housing is tightened to much it can deform the plastic slightly, and pinch the assembly, usually loosening the screws 1 to 1/2 turn can help it recoil.
if even completely off the truck, it is still not recoiling, there could be an issue with the spring, or might have just popped out of the slot.
pull starts are pretty cheap, so you may elect to get a new one altogether, i do recommend practicing with the old one on rebuilding them. PITA at first, but gets easy after a few times.

Thanks so much. The hold one recoiled the second I got it off the engine. I purchased another one for good measure and intentionally did not tighten as much when I put it on. Same issue. I noticed th st time I remove the glow plug it will recoil very slowly.

 

[D3MON]

Thanks so much. The hold one recoiled the second I got it off the engine. I purchased another one for good measure and intentionally did not tighten as much when I put it on. Same issue. I noticed th st time I remove the glow plug it will recoil very slowly.

That is leading me to believe the engine may be a bit gummed up, I would take off the back plate and rinse out with old fuel, denatured alcohol, or brake cleaner (non chlorinated)kind of slosh it around in there, spin the engine a bit, and repeat. (Make sure to let completely dry then use an after run oil of your choice (I use marvel mystery oil, but 3in1, air tool oil. Etc will work) take off the head and do the same in the top of the engine.
On one of my pull starts, I have the screws backed off from tight 1/2 turn so it doesn't bind.

 

[SpeedRacerRx]

Thank you so much. I'll do this tonight! Really appreciate your help. Local hobby store wanted $75 bucks to "look at it"

 

[D3MON]

ouch, that is insane, i guess they do need to make their money though, but that is steep. just remember for almost any hobby grade RC, they are designed to be repaired, dont be afraid to dig into them, its a good idea to take pictures or a video as you disassemble, any questions post pictures here, or even a video if you would like. there are many very knowledgeable people on here that can get you out and burning nitro again.

 

[olds97_lss]

Yep, sounds like the one way bearing is gummy. It's not inside the engine, so any oil you put in the engine didn't help with the OWB. Over time, fuel/oil seeps out the starter shaft and gets on the bearing, which keeps it lubricated, but after sitting, the oil in it is likely all gummy now.

Take the one way bearing off, soak it in denatured alcohol, then run a wetted with DA paper towel through it and spin it on the towel to help work the gunk out. When you think it's clean, clean off the starter shaft as well, then put a drop or two of light oil on the OWB and reassemble.

 

[Twiztid420]

Yep, sounds like the one way bearing is gummy. It's not inside the engine, so any oil you put in the engine didn't help with the OWB. Over time, fuel/oil seeps out the starter shaft and gets on the bearing, which keeps it lubricated, but after sitting, the oil in it is likely all gummy now.

Take the one way bearing off, soak it in denatured alcohol, then run a wetted with DA paper towel through it and spin it on the towel to help work the gunk out. When you think it's clean, clean off the starter shaft as well, then put a drop or two of light oil on the OWB and reassemble.

I am feeling the same way. I would clean that one way bearing and clean the engine out.

 

[SpeedRacerRx]

You guys are great! Thank you all for the input. Going to work on this in the next few days and will report back here with my results!

 

[SpeedRacerRx]

Hi guys. I finally got around to taking the engine out and soaking in DNA. Placed a few drops of Marvel oil in all areas and put back together. Attached pull start and backed off slightly after tightening. Still cannot get a recoil with engine mounted and glow plug in. Any ideas? At this point I am thinking to just buy a 3.3 to drop in

 

[Twiztid420]

If the engine is spinning freely and you have good compression, I doubt it's the engine that's causing the problem.

 

[Twiztid420]

I know my dynamite .28 did that for a little while when it was new. It would only recoil a small amount but it was enough for it to turn it over once. I would pull it lightly a couple times until it fired and it would recoil then. After awhile it stopped doing that.

 

[SpeedRacerRx]

Even before I mount the engine back and I try to pull start I cannot get the pull start to recoil

 

[Twiztid420]

Maybe the OWB is bad. I would try a new one before buying a new motor.

 

[SpeedRacerRx]

I have recoil! About 100 manual spins by hand and it worked out

 

[Twiztid420]

I have recoil! About 100 manual spins by hand and it worked out

Lol! Good for you! Now go burn some nitro!

 

[alfredwong2003]

I think the problem was the pull start plate and shaft needs cleaning. Once you pull it enough, the gum get loose. Whenever I get a used engine, there are steps I used to follow, before I even try to start it. Sometimes on an old pull starter, the spring will need cleaning too, the can get gummed up as well, but since you have a new one, that would not be the issue.

 

[Shockbender98]

You probably just flooded it, take the glow plug out, flip the car over, and pull the engine over. While your at it make sure the glowplugs still good

 

[olds97_lss]

The cord itself also gets gummy. I have some old ones in a drawer that won't retract and the cord is just soaked with old oil. If I take them apart, clean the clock spring, housing and soak the cord in DA, then drag it through a pinched paper towel a few times, they usually come back to life. In most cases, easier just to throw away the old cord and get a new one.

 

[Shockbender98]

Is there a leak in the crankcase? Causing it to get the pull start oily, clean it all out, run it, and take it apart again to see if its oily