Main Hydraulic Pump Motor

RestoRay · Jan 31, 2021

Hello I have owned my 743 for 15 years, maintained it regularly. Today I was plowing snow on the driveway and it came to a grinding stop-barely any drive or boom/bucket lift. Sounds like the main hydraulic pump motor packed in.. it's literally screaming when I lift the cab. I can't stand letting it run anymore in case it creates further damage or grenades! Please note: I was able to keep it in high idle and slowly move (barely) it out of the main driveway. **This was an instantaneous failure, there was no sign of any pore operating performance that I could hear or see prior. No low oil condition. Lookin for your insight, please. I'm mechanically inclined with a shop but haven't had any experience tearing a Bobcat hydraulic motor apart. What am I in for? I noticed some reman sellers online. Any recommendations Are there complete rebuild kits? Thank you in advance!

RestoRay · Jan 31, 2021

Here is a google drive link containing a video and sound. https://photos.app.goo.gl/8VCMX1eNoan8FvVc9

Phil314 · Feb 1, 2021

RestoRay said:
Here is a google drive link containing a video and sound. https://photos.app.goo.gl/8VCMX1eNoan8FvVc9

To me that sounds like stripped splines on a shaft.
The travel/tandem pump and the lift/curl pump are 2 separate pumps
It's unlikely you suddenly lost both at the same time.
This also points to a broken coupler/stripped splines between the engine and pumps
I believe the 743 uses some kind of u-joint/coupler between the engine and pumps.
That's where you want to start looking.

Tazza · Feb 1, 2021

Phil314 said:
To me that sounds like stripped splines on a shaft.
The travel/tandem pump and the lift/curl pump are 2 separate pumps
It's unlikely you suddenly lost both at the same time.
This also points to a broken coupler/stripped splines between the engine and pumps
I believe the 743 uses some kind of u-joint/coupler between the engine and pumps.
That's where you want to start looking.

That is a noise like fingernails on a chalk board, not a nice soudn to hear at all.
It does sound like something is stripped.
It is possible that the spline at the motor end is stripped, there is a chance it is also the coupling between the drive pumps and the hydrulic pump too. If you remove the end of the hydraulic pump, you will see a small splined shaft, this shaft has splined joiners to link it to the shaft that goes to the motor end. It is possible one of these has gone too. If you try and turn this shaft with the motor attached, it should not turn. If you pull the pump casing and rotor out, ensure the vanes go back in the same spot as they will have worn in.