M700 steering problem

[bobcatbros]

My M700 sometimes will quit driving on the left side. When I lift the boom arms, it will start driving again. It works great when it is working, but will quit and start again several times a minute. When it quits, it will not work forward or reverse. The right side works great. Does anyone have an idea what the problem could be??

 

[Tazza]

Is this a hydrostatic or clutch drive system?

 

[bobcatbros]

Is this a hydrostatic or clutch drive system?

Hydrostatic drive

 

[Tazza]

Hydrostatic drive

Well its an older machine, i would suspect it simply pump wear, this can be repaired if you are willing to spend some time to do so. You could even start be checking the high pressure reliefs in the drive circuit, it could simply be a bad one on that side.
I don't know if it runs a port block with a hidden filter or not, but the old 731 and early 743's had a square block on the hydraulic pump that had a hidden filter behind a hose fitting that caused lots of trouble when it plugged up.