1990,, 91or 92, 753 Bobcat with BOSS control. I installed a new Aux Control Module from Bobcat. When done, I could tell the solenoids were working but I did not have the grapple on to test the system. After connecting the grapple, I still do not have correct flow and pressure like I should. My drive motors, lift and tilt are working fine and have plenty of power. I did a check to make sure the cylinders on my grapple were not leaking past the packing, and it was good. I could disconnect the quick connections from the bobcat with the retracted or extended, and the cylinder is hard locked and will not move up or down. I did this for both cylinders in case one was blown causing a blow by issue. My grapple cylinders are in good condition. I also checked to see if I got fluid flow from each hose when I triggered the buttons on the handle, very quickly, and both hoses shot fluid at high pressure for 15+ feet. I have not done a pressure test yet, as I don't have a hose and flow control valve set up, and I am pretty sure Bobcat won't rent theirs…lol
Given how my lift, tilt and drive work, I don't think my issue is with my pump. I think it is a valving issue.
For my first test, I isolated the system by connecting the hoses from the quick connect direct to only one cylinder and here is what I observed.
When I connected the bottom connector on the Bobcat to the top of the cylinder, I could actuate it up and down, although it did so very slowly, and with the button not actuated, it seemed to drift down. I could even push it down manually by just putting weight on it. Then I reversed the connectors on the cylinder, and it would not move. The hose would energize, and you could see them flex, but the cylinder would not move.
I have two ideals, and I am looking for help or input on a direction. (See Videos One works and one doesn't work)
1. The rear auxiliary valve has two check valves that probably have to work together to allow one side to release while the other one holds pressure based on which solenoid is energized for the auxiliary circuit on the main hydraulic control valve body. One of those check valves may be blocked or bad. (Ref Items #4 on Rear Auxiliary Valve Diagram) Check Valve-6664212 - $158ea +tax
2. The Solenoid valves or Spool in the main hydraulic control valve body. Maybe they are stuck or clogged? Solenoid Vale- 6653395 – $505ea.+tax
I am open to any input on what I should look at next.
Thanks
Given how my lift, tilt and drive work, I don't think my issue is with my pump. I think it is a valving issue.
For my first test, I isolated the system by connecting the hoses from the quick connect direct to only one cylinder and here is what I observed.
When I connected the bottom connector on the Bobcat to the top of the cylinder, I could actuate it up and down, although it did so very slowly, and with the button not actuated, it seemed to drift down. I could even push it down manually by just putting weight on it. Then I reversed the connectors on the cylinder, and it would not move. The hose would energize, and you could see them flex, but the cylinder would not move.
I have two ideals, and I am looking for help or input on a direction. (See Videos One works and one doesn't work)
1. The rear auxiliary valve has two check valves that probably have to work together to allow one side to release while the other one holds pressure based on which solenoid is energized for the auxiliary circuit on the main hydraulic control valve body. One of those check valves may be blocked or bad. (Ref Items #4 on Rear Auxiliary Valve Diagram) Check Valve-6664212 - $158ea +tax
2. The Solenoid valves or Spool in the main hydraulic control valve body. Maybe they are stuck or clogged? Solenoid Vale- 6653395 – $505ea.+tax
I am open to any input on what I should look at next.
Thanks
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