970 hydraulic system getting air locked

[petebert]

Power assist 970, every time it sits I have no hydraulic pressure and nothing works. To fix it I have to open the brake bleeders and get the air out. Any ideas where to start? No visible leaks except where the remote linkage attaches between the cab and fuel tank. Once I get it bled it operates fine all day.

 

[John Saeli]

Power assist 970, every time it sits I have no hydraulic pressure and nothing works. To fix it I have to open the brake bleeders and get the air out. Any ideas where to start? No visible leaks except where the remote linkage attaches between the cab and fuel tank. Once I get it bled it operates fine all day.

I would start w/ the pump intake ORing A30915.

 

[Case Nutty 1660]

If the suction oring does not fix it, you have a couple other things to check,, the suction screen may be plugged creating a vacuum making it air lock or the pump is shot

 

[petebert]

I would start w/ the pump intake ORing A30915.

I'll check it out, I've got the service manual and it doesn't seem to bad to get to.

 

[petebert]

Pump is out, should there have been any oil in there? A few tablespoons came out when I took the lines off but that's about it aside from tiny bits of pooling.

Which O rings should I be looking at? Just the external #10, or should I open it up to look at #4 and #20. If I take that cover off will there be other gaskets I need to replace? O ring #10 appears to be fine but I might as well replace it.

 

[John Saeli]

My advice is to pull the pump and inspect #10. You can also look @ #4 w/out disassembling. You can also pull the drain plug in the rear which is about directly under the screen. If chunks of crap come out, it could possibly mean the screen is plugged. If the oil comes out clean, I doubt it's the screen. My experience with this problem you have is always #10. Be sure the oil you are using is a quality Transmission-Hydraulic Oil, not a straight Hydraulic Fluid which I wouldn't use on a bicycle chain. I am shocked-shocked at the number of customers calling here, w/ problems who tell me "Oh I buy whatever hydraulic fluid is on sale". Shocked!!

 

[petebert]

#10 visibly appears fine, I assume #10 is associated with the same tube but I can't feel or see it. Not sure where exactly it's supposed to be but so far can't find anything. I use Lube King Case IH Hydraulic Fluid.

 

[John Saeli]

In the 1st pic, the O ring as installed looks all cracked.

 

[petebert]

oops typo there, I wrote 10 twice. I can't find #4 by looking or feeling down into that tube.

I plan on doing #10, it's probably been there since 1971

 

[Case Nutty 1660]

number 4 is inside the pump bore to seal the rear end of the suction tube

 

[petebert]

I pulled the tube and did both o-rings. Also did the hydraulic filters which I didn't suspect because I keep up on those but decided to do them anyways. It appears the tractor is now good to go. Takes about 5 seconds for the pressure gauge on the dash to activate.

I'm am wondering about the amount of crud I found on the filter housings. Should I be concerned or normal? Probably around 300 hours on them. When I bleed the brakes, that fluid comes out looking good but the stuff that came out of the filter housings was dark and there might have even been some shiny specs in the drain pan.