No tickover/idle problem
I hope someone can point me in the right direction here because I am at a loss. First I'll give some background of the problem.
A friend bought a 2.5 t-maxx that was in a real state and needed a full overhaul. The engine ran fine but when it was opened to see if there was any problems we found a small part of the piston skirt missing so as part of the overhaul a piston/rod/sleeve set was ordered.
When it was all cleaned and ready to go, it took a bit of fiddling to initially get the engine to run, eventually it started and we set out to run it in with the traxxas method, but we had one major problem in that we had no tickover.
As soon as the throttle was let go it would die, sometimes it would fire up again straightaway and other times it was a bit of a bugger to get going again.
Initially I thought it was because of the piston being tight in the sleeve and it was mechanically tight. Now we have run about 5 tanks through it and still no tickover, it just dies. I've swapped out the OWB and that made no difference, wondered if the clutch spring had snapped but that was fine.
I have had the carb to pieces, all of the O-rings look ok, no tears and they are all proud of where they sit. The ones where the carb seats weren't great so I replaced them with new ones. Needles look ok too.
So it is hard to start and has no tickover at all. When it is running it's temp is about 240f.
Are we looking at an air leak somewhere? It's not popping glow plugs and there's no discolouration on the plug it still looks like new.
Any pointers in the right direction would be appreciated.
Make sure the carb gap is 0.7-1.0mm at idle or full brake. Also, verify the cut-out on the piston is facing the carb.
Thanks for the reply.
The carb gap is deffo at just under 1mm as I did it myself last night. The only thing I cant yet verify is which way the piston is facing in the engine. I'm supposed to be seeing him tomorrow so we can have another tinker so if he can't remember I'll rip off the backplate and see which way it's situated.
he brought he engine up and I stripped it down, the piston was set the wrong way around so hopefully when the engine is back in the car it will be ok. Will post again when I know more.
Thanks for the help.
I recently tore down my 3.3 and rebuilt/sealed the engine. I had the same problem...no idle but would run at 1/4+ throttle. it was the piston orientation, I had the cutout facing the wrong way. flipped it around and haven't had any problems since then.
Well, I went down today and it's not much better. It starts a little easier but, we still have no tickover. Before, it stalled out at about 1/4 throttle now we can get the idle down to just about what sounds right and then it dies.
Tried loads of tweaking to get it right but to no avail. Thinking of taking the carb off my revo and trying that in his maxx to eliminate a possibly worn carb.