T300 bobcat drive motor not moving on left side only

[groskeytree]

Hello there I'm new here, I have a 2006 T300 tracked bobcat. I recently had an issue with a drive motor failing to operate suddenly on the left side of the machine when sitting inside. A few years ago we replaced the drive motor on the left side due to loss of drive power on that side. We cleaned out the case filters, changed the hydraulic filters and put a rebuilt unit on there. It's been very good with no noticeable issues besides maybe a slight lack of power overall. We did have an algae issue in the fuel tank I pulled the motor and cleaned the tank and replace the sending unit and fuel lines. That was a couple years ago. Now for the last year it seems like the machine is struggling more especially when pushed hard. The hydraulic charge pressure seems a bit low at idle is has about 240-250psi at idle 350-380 at full throttle. The most recent major issue we have had is we were moving some pieces of concrete around the yard and as we were backing up the machine the left side locked up. We could figure out the issue so we let it sit there for about 2 weeks as we had other things going on. We came back this weekend fired up the machine and it started moving around like normal. 10 mins later it locked up again and now is throwing a low charge pressure warning and shutting down the machine at idle. I'm puzzled and would like some help.

 

[polishpete]

WELL IT COU;D BE A few things check the easy first

 

[polishpete]

if u still have that oressure with a necaicakky guage thats good
belt could be slipping charge preure sensior could be no good
what coodes praably belt

 

[thoughtbelt923]

Sounds like the brake in the left motor may be leaking excessively. You can do a case drain test which there is info out there online. Basically comparing the flow back from the drive motors to the case drain filters one side at a time. If you go that route, I'd also consider pulling the case drain filter and checking for debris.

You can also compare the charge pressure at high idle after startup, then watch the drop after pressing the brake release/press to operate button. If you see a steep drop and it doesn't recover, that's another indicator of excessive leakage. If it's leaking too much, the charge pump inside your hydro-static pump won't be able to recover.

It working fine after startup then not working later could be due to the hydraulic fluid warming up and becoming thinner which consequently makes leaks more pronounced.

 

[groskeytree]

if u still have that oressure with a necaicakky guage thats good
belt could be slipping charge preure sensior could be no good
what coodes praably belt

No codes just shuts down from low charge pressure

 

[groskeytree]

I have a update, I narrowed it down to the big hoses that feed the left side drive motor, the brake hose did not change anything I capped everything off and tested the pump charge pressure, at full throttle it's at about 420psi when I hook up the left side it drops down to 290psi sometimes lower and shuts down. So maybe the drive motor?

 

[polishpete]

theirs your problem