751 Hydraulics stopped after seal replacement?

[bradyr2003]

I have a 1998 Bobcat 751. The Bucket Tilt spool seals were leaking so I replace them both. Front and Back. Complete and refilled with oil. 30 minutes of operation and the Lift spool seals blew (Backside).

I know now, that when you replace one set, you should go ahead and replace both. Completed the lift seal replacement.

Things worked on for about 30 minutes and then the #1 cylinder fuel line from the pump to the injector broke at the line fitting. Lucky I had a one from a set I bought a while back. Fixed that and started the machines. Worked the machine a few minutes and the Hydraulic filter light started come on and going off. coming on and going off. As I continued to finish the small job I was doing the lift and tilt hydraulics and the drive motion all began to slow down and then shortly afterwards came to a stop. Nothing would work with hydraulics, no noises, whining, everything sounded OK just nothing would work. I rested the machine for about two hours and tried it again, both the drive ( forward and Reverse ) and the lift and tilt work.

This lasted about two minutes and then slowed to a stop again. Talked around and felt the main hydraulic filter was plugged and both case drain filters. Purchase and installed both filter. The machine crank ups and the hydraulics worked about two minutes and then did the same thing, quickly slowed down to nothing and stopped working. Also the Filter light is back on? Could there be contamination in the oil and it has simply stopped up the filter again? I would think this is a simple problem for some, but it has me going crazy. Any help or direction would be greatly appreciated.

 

[SSdoxie]

I have a 1998 Bobcat 751. The Bucket Tilt spool seals were leaking so I replace them both. Front and Back. Complete and refilled with oil. 30 minutes of operation and the Lift spool seals blew (Backside).

I know now, that when you replace one set, you should go ahead and replace both. Completed the lift seal replacement.

Things worked on for about 30 minutes and then the #1 cylinder fuel line from the pump to the injector broke at the line fitting. Lucky I had a one from a set I bought a while back. Fixed that and started the machines. Worked the machine a few minutes and the Hydraulic filter light started come on and going off. coming on and going off. As I continued to finish the small job I was doing the lift and tilt hydraulics and the drive motion all began to slow down and then shortly afterwards came to a stop. Nothing would work with hydraulics, no noises, whining, everything sounded OK just nothing would work. I rested the machine for about two hours and tried it again, both the drive ( forward and Reverse ) and the lift and tilt work.

This lasted about two minutes and then slowed to a stop again. Talked around and felt the main hydraulic filter was plugged and both case drain filters. Purchase and installed both filter. The machine crank ups and the hydraulics worked about two minutes and then did the same thing, quickly slowed down to nothing and stopped working. Also the Filter light is back on? Could there be contamination in the oil and it has simply stopped up the filter again? I would think this is a simple problem for some, but it has me going crazy. Any help or direction would be greatly appreciated.

Sounds like the drive belt from engine to pumps is slipping, so loose that it won't squeal.

 

[J_J]

I believe I would install a hyd gage somewhere and monitor the pressure. The pump might be sucking air.

How many pumps in your system?

Are you using the correct fluid?

Is the engine shutting down or just the hydraulics?

Put a gage on the pump and see what is happening.

If you do not see any pressure when a valve lever is activated, the pump is not pumping.

Check for a collapsed hose. If you can, see if you can squeeze the suction hose. Check for air leaks also.