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Post by Oatking on Jul 25, 2023 0:41:13 GMT -6
I was using my 946 versatile tractor on a field scrapper when I gradually felt like the tractor was losing oil pressure on the hydraulic levers.
I had the hydraulic pump replaced a few years ago and I had ample oil in the reservoir.
Could it be the hydraulic filters? I thought maybe the hydraulic valve stack on the left side of the rear fender might have a problem. Not sure now what is causing very slow operation of hydraulics .
Any ideas?
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Post by meskie on Jul 25, 2023 7:24:04 GMT -6
Could be a few things causing the issue. Filters could be dirty.
Do the hydraulics work better when you turn the steering wheel? Your priority valve could be sticking or the pressure compensation valve could be not telling the pump to go to full stroke.
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Post by northernfarmer on Jul 25, 2023 10:00:17 GMT -6
While it may not tell much as per the problem, a simple test would be to plug in a gauge to one of your outlets and see what the maximum pressure is to possibly rule out the pressure relief system. It won't tell you what the flow is nor if you have some sort of restriction in the system. Aside from replacing the filters, does that unit have some type of screen in the hydraulic tank or on the suction side of the pump that could possibly be plugging up.
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Post by billybigrigs on Jul 25, 2023 17:05:09 GMT -6
There’s a block on the side of the hydro pump with a little hydraulic line that goes all the way to the valve stack at the back of the tractor. This block with the line tell the hydro pump to speed up or slow down based on pressure, so you’ve probably got a leak in the hose or a oring gone in the little block. I’ve had this problem on my 876.
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Post by snapper22 on Jul 27, 2023 16:13:08 GMT -6
Those valve banks are famous for eating those little o rings and getting stuck in little ports in the block. Once had a similar issue in my 2425 with a very similar if not the same bank and traced problem back to a broken o ring stuck in a port. Think it was constricting the load sense line going back to the pump. My 946 was having valve bank issues and I sent it away to get resealed. Ended up costing a fair penny more than a used one from the wrecker which ended up buying anyway because they buggered up on the job. The 946 has the bank in the worst possible place to get at too so doing any work to it sucks.
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Post by Oatking on Jul 27, 2023 17:59:18 GMT -6
How did you get the o- rings out . You’re not kidding what a peta it is to get at that valve bank . Did you have to take the whole bank off ? Never attempted this job before .
The line big Al talked about I replaced a few years ago.
It seemed all three valve hydraulics worked very slow so it’s not one specifically .
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Post by snapper22 on Jul 28, 2023 9:33:43 GMT -6
How did you get the o- rings out . You’re not kidding what a peta it is to get at that valve bank . Did you have to take the whole bank off ? Never attempted this job before . The line big Al talked about I replaced a few years ago. It seemed all three valve hydraulics worked very slow so it’s not one specifically . You just about have to take the bank off because of its location. Think I first got a parts diagram of the thing and started tearing it apart carefully. Just happened to find a little broken o ring stuck in a small port. Reseal kits from cnh are horrendous expensive. Think it’s a rexroth bank and they do not give out jobber numbers for seals. |
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Post by snapper22 on Jul 28, 2023 9:36:46 GMT -6
How did you get the o- rings out . You’re not kidding what a peta it is to get at that valve bank . Did you have to take the whole bank off ? Never attempted this job before . The line big Al talked about I replaced a few years ago. It seemed all three valve hydraulics worked very slow so it’s not one specifically . You just about have to take the bank off because of its location. Think I first got a parts diagram of the thing and started tearing it apart carefully. Just happened to find a little broken o ring stuck in a small port. Reseal kits from cnh are horrendous expensive. Think it’s a rexroth bank and they do not give out jobber numbers for seals. I’d add too that where the load sense line port is is where I’d start my search but get a diagram so you know where rings, seals, springs, and balls should be. I’m by no means mechanical inclined but take you’re time it’s not that bad. |
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Post by OptimallyDismal on Jul 29, 2023 12:48:03 GMT -6
I am starting to think this could be my 846 hydraulic problem as well, especially the load sense aspect.
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