Hydraulic pump check valve?

Lester M

New User
I am working on a TE20 hyd system. It would not work at all and I found the gasket under the lift cover blown at the pressure tube.Replaced the gasket and now the lift arms will raise with NO LOAD. When a load is applied they start to raise and I can see the control valve back out to a neutral position. My question is it possible that the pressure valve is stuck closed?
 
Sounds like your control valve is stuck in the foward position. If the lift arms are up, make sure the engine is off and remove the side plate and pull the contol valve toward the rear. The valve body should move back about an inch and the lift arms should drop. Make sure the "T" shaped valve stem is hooked to the lower arms on the "H" shaped control fork. If they are then the valve may have some crud that"s causing it to stick.While you"re there make sure all the pieces of the control linkages are there and are attached properly.
 
Is the cork friction disc still there at the control lever? When was the last time the lift was adjusted? Is the spring that goes from the control valve fork to the lift cylinder still there and not broken?
 
The lift lever works fine and all the linkage is in the proper place. The spring is still attached. While looking thru the inspection hole I can see the control valve is working properly. When I use the lever to raise the lift arms (with a load on them)I can see the linkage move the control valve out to the neutral position. I can manually pull the control linkage and move the control valve back into the pump and then the lift works properly. There is back pressure on the control valve. That is why I was wondering if the relief/check valve might be stuck open.
 
No, if the relief valve was stuck open the arms wouldn"t lift or would lift very little because it wouldn"t have the pressure to lift them. If there isn"t anything mechanically wrong with it then you need to adjust the lift. Adjust the draft control spring and then adjust the control quadrant. The control fork is up against the end of the control lever, but if it gets out of adjustment then it allows play in the control fork which means play in the control valve. Do you need the procedure for adjusting the lift?
 
Thanks for the info. I can get the procedure for the adjustments. Will report back when I can get this done.
 
I checked and made the adjustments for the control linkage and I still have the same problem. With no weight on the lift arms, I move the lever to raise position and the lift arms come up. I add 50 lb of weight to the lift arms and move lift lever to raise position and the arms start to raise but then stop. I can see thru the side inspection that the control valve is moving rearward. I can reach my fingers thru the hole and hold the fork and valve I forward and the arms work properly. Somehow, hydraulic pressure is moving the valve rearward. I am beginning to think I have a pump internal leakage problem.
 

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