TL12v2 Ongoing overheating issue when using a brush cutter - original post 4-14-24

[Boston3220]

Hi all,
I'm still having an issue with my TL12v2 overheating after 15-20 minutes when using the 72 inch brushcutter. When the warning buzzer goes off I shut off the brushcutter and the engine temp cools down after 4-5 minutes at which time I re-engage the brush cutter and get another 3-4 minutes out of it until the engine overeheats again. The radiator fins are clear and all fluid levels are good. I have a theory about what the actual problem might be and maybe some hydraulic motor/gearbox compatibility experts on this site can weigh in. This brush cutter was originally a cheap Chinese knockoff. I replaced the Chinese hydraulic motor with an American made one. I also replaced the gearbox with an American made one. The skid steer never overheated with the old motor and hydraulic pump but now it does with my replacement parts. Is it possible that the new hydraulic motor and gearbox aren't matched with each other, meaning the pump flow is too much for the gearbox, causing back pressure and making the engine overheat? One thing I discovered this afternoon while using it the more I back off on the throttle the longer it lasts before it overheats. To me that means the pump is too big for the gearbox. For now I think I will borrow my son in law's 72 inch brush cutter and if doesn't overheat the engine, then that is the problem. Any thoughts?

 

[Boston3220]

Hi all,
I'm still having an issue with my TL12v2 overheating after 15-20 minutes when using the 72 inch brushcutter. When the warning buzzer goes off I shut off the brushcutter and the engine temp cools down after 4-5 minutes at which time I re-engage the brush cutter and get another 3-4 minutes out of it until the engine overeheats again. The radiator fins are clear and all fluid levels are good. I have a theory about what the actual problem might be and maybe some hydraulic motor/gearbox compatibility experts on this site can weigh in. This brush cutter was originally a cheap Chinese knockoff. I replaced the Chinese hydraulic motor with an American made one. I also replaced the gearbox with an American made one. The skid steer never overheated with the old motor and hydraulic pump but now it does with my replacement parts. Is it possible that the new hydraulic motor and gearbox aren't matched with each other, meaning the pump flow is too much for the gearbox, causing back pressure and making the engine overheat? One thing I discovered this afternoon while using it the more I back off on the throttle the longer it lasts before it overheats. To me that means the pump is too big for the gearbox. For now I think I will borrow my son in law's 72 inch brush cutter and if doesn't overheat the engine, then that is the problem. Any thoughts?

With the help of a hydraulic specialist I finally solved the engine overheating issue. Running 23.2 gpm of hydraulic fluid through the 12 gpm hydraulic pump on the brushcutter was causing the engine to work harder thus causing it to overheat. I dialed the flow rate to the brushcutter back to 12 gpm and the engine temp stayed in the normal operating range. This pump is a replacement unit and apparently I was sold the wrong one. I'll need to replace the pump because running the brushcutter at 12 gpm isn't quite enough to do a good job.