970 Hydraulic Problems

Scott_S

Member
Have powershift 970 that is on the high side of all the serial number splits. This tractor stays hooked to a bushog and gets a couple of hundred hours a year. Have had a couple insults to the hydraulic system in the past few weeks and now have some problems.
Had a brake line start leaking and did not notice it until steering suddenly got weak and shifting was jerky. Shut it down immediately. I replaced the line, refilled with tractor supply fluid, and drove it less than half a mile to home. When I stopped at my shop, the transmission wined and it stalled the motor. Let it sit for a few minutes and restarted and the transmission sounded/operated normal again. Did not run it again.
Drained the fluid and found it very nasty with water in it. Filter canisters both had some grey sludge in the bottom of them. Nothing found on the button magnets I have in the filter housings and drain plugs. Washed the shift linkages on top of the transmission, new filters, and refilled with Hytran.
All seemed back to normal after the fluid and filter changes. Ran a total of 6-8 hours and noticed that the steering and 3pt were getting slow. Does not have the usual squeal when turned to the locks or brakes applied.
Put gauges on the powershift test ports and everything is 175 or 0 when it should be. Lube pressure is 65 or 0.
Put a gauge on the brake/steering filter and get 0 at idle. Goes to about 100 at full throttle. Turning the wheel gets 700-1200 until lock and then goes to 2200. Applying brakes gets 1700-2200. Both with only a groan and not the usual squeal. Lube pressure on the powershift drops to 0 with any steering or braking. No changes with any combination of powershift ranges, PTO, 3ph movement, or remotes.
Have searched the archives for similar problems and have not found anything like this. See a single line in the manual that says if lube pressure goes to 0 with steering/brakes, low flow pump is bad.
I do not have a flow meter. If I have to have one for further diagnosis, please recommend something. Not sure exactly what is needed.
Sorry for the long description. I read this site daily but seldom post. It is impossible to fully express my thanks to all of you for the knowledge available here and your willingness to share. I can usually find the answers to problems with all my old stuff just reading here.
Thanks,
Scott
 
I'd prefer to flow check 8gpm pump but since lube press drops to 0 prob safe to replace hyd pump. Pumps are available aftermarket.
 
Dawg is correct, when the steering is locked the reverse lockout spool looses its supply and drops out if the 8 gpm pump is weak, it is fed from the lube supply. It is probably not a coincidence that the pump failed when the steering started to act up, the pump probably lost lubrication long enough to overheat.
 
Thanks for the responses!
Should I get a flow meter to verify or is there a way to visually inspect the pump for damage?
Are there any other things I need to replace or address when changing the pump? I am assuming it also needs another fresh fill of Hytran?
Scott
 
After removing pump take it apart. You will see a gouged up housing and rough gears on 8 gal side. New pump from cnhwhatever is approx $1500, $1200 from Hy capacity. Both prices are STUPID.Recommend getting a used pump from Elmer's Repair(787)857-3248 Best salvage yard I've dealt with in 45 years.
 
Same on Red tractors 06 through 36 series, mash brakes while cramping steering. Lube light comes on....steering pump bad.
 
All the oil that flows from the pump goes through a high pressure filter, assuming the cold oil relief cartridges are in place in the bottom of the filter elements any debris from a pump failure should be caught. This all happened over a brief period of time If I understand correctly, I would take the filters out and blow out the lines, install new filters, Prelube the new pump by putting Hytran in the inlet port and turning the pump till it comes out the other port, this is vital, Also replace the Orings on the big feed tube. Be very careful as those Orings are easy to cut with the tube if not careful. I always break the sharp edge on the tube with a grinder then wire brush to smooth where it goes back into the tractor.

If you want to be perfectly certain a flow test is in order. that would remove all doubt but my experience ad Dawgs also obviously points to pump failure.
 

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