CASE 2594 Slipping

Was mowing hay with my 2594 and slowly noticed it losing speed last year. As it lost speed began to hear a whining sound coming from right beneath me. The slower it got the louder and faster the whining got. Slipped more at an idle than at higher RPM, you can make it stop moving at an idle with the brakes pushed. Did it in all gears, all ranges. Powershift shifts fine, no delays, no hard shifts.

Split it in two 3 weeks ago, put new torque limiter friction disks in even though the disks in it didn't look burnt or worn. Followed the service manual, springs toward the flywheel on the first disk, springs toward the back on the second disk. Pressure plates look ok, they are very smooth where the clutch disks have been, same with the flywheel. The surface texture on the flywheel is gone where the friction disks press to it, its completely smooth whereas the rest of the flywheel has a texture to it. Belleville spring measured out in tolerance according to the service manual. Put it back together with new filters, still slipping. It was def better than before but still slipping when pulling, still slips less at higher RPM and more at lower RPM. Same whining noise that gets louder and faster the longer it slips and goes away as it picks up speed. Checked pressure to the hydraulic pump from the transfer pump it was good, pressure to the c1-c6 clutches was good. Went through all the electronics on the solenoids, proper solenoids energizing when in the different ranges. Cleaned the spool to the torque limiter nothing out of the ordinary there. Cable looks adjusted, spool is bottoming out like its supposed to. Popped the PTO housing off and checked the sump screen, it was fairly clean didn't take much effort to clean it. No large chunks of metal or pieces floating anywhere in the belly, just normal metallic flake from a 10,000 hour tractor.

Put the PTO housing back on, still slipping for 5 minutes or so I ran it around the shop. I stomped down on the brakes hard to see if it would stop moving completely at a higher rpm and it suddenly lunged forward and stopped whining completely. For an hour it ran fine, proper speed no slipping no whining even at super low rpm pulling a steep hill. After 30 minutes it started again. Split the tractor again, clutch packs look the same, don't look burnt, I can see some minor evidence of them slipping on one of the pressure plates.

I'm out of ideas on things to check. Only thing I came up with today was possibly the flywheel texture being gone but that seems like a stretch. Anyone else ever hear of something like this? Thanks.

I highly doubt the limiter clutches are your problem, those get really ugly if they are slipping that much. The flywheel surface does get polished a bit from normal wear
but I have never had one resurfaced unless there was noticeable wear. From my experience if the limiter is weak slippage is more at high rpms, not low. I have no idea
what the whining noise would be. I would spend time making double sure three pressures are good, low pressure standby pressure which is controlled by the compensator on
the hyd pump. Lube pressure in the PS control valve and trans pressure controlled by the flow divider. If all those are at proper operating pressure that tractor should
pull great regardless of engine rpms. Rod.

Thanks for the info and response. I will get it slapped back together and do some more pressure checks. Does seem like it might be
pressure related since it slips less when its at operating RPM versus idle, but all the pressures I've checked have been where they should
be. I checked the remote pressure prior to this most recent split and it was up around 2300 psi, lift, steering, brakes, etc all operate
fine. I don't have the setup to check flow in gpm though. The way it acts reminds me of how a shaft will spin with a sheared keyway or lost
pin, spins fine up to a certain point until the load overcomes the friction of the sheared key.

I am no expert only been in a couple of those Case power shifts and they were both 1070s, I have been through some PS trans in other brands. I would just like you to clarify if you have taken apart the C1 to C6 clutch packs to inspect them to that depth. You mentioned that ..after 30 minutes it started doing it again.. then you pulled it apart and you say the ..clutch packs look the same, not burnt.. that is really all you tell us about the rest of the trans besides the torque limiter. I do not know the exact layout of those 6 speed power shifts but usually there is a way to apply air pressure to check the apply and piston leakage. Not sure what this will clarify other then giving us a better idea how in depth you looked it over. One other thing is you mention looking at the suction screen with the PTO out. Does this give you pretty good access to it so you know it is clean? I am just going by a video of a guy working on a 2390. He was foo foo the design due to having to split the tractor to pull it out where a Deere it just unscrews from outside. Again not an expert just trying to help you think through what you have going on.

A very weak P Steering pump can affect powershift operation, but you have never mentioned anything unusual with its operation. It would affect lube pressure but only when steering or using the brakes. Sometimes this problem can be missed when testing because the tractor is stationary while doing so. But having said that if the tractor has good steering and brakes the pump should be good. I have thought of the mechanical slippage possibility also, But in my 50 yrs of servicing those tractors if something was broke or sheared the tractor did not move period. Another pressure to check is charge pump pressure, a drive key can shear in the pump and give you the same symtoms as a plugged suction screen. Good luck, Rod.

I checked pressure to the C1-6 clutch packs, I didn't split it between the trans and the torque tube and disassemble the powershift clutches, its split between the engine and torque tube. The torque limiter clutches aren't burnt. Based on everything I've read and experienced with these tractors (I've got two of these older cases) it seems unusual it would be in the powershift with every single gear and range having the same symptoms and it shifting like a top through all the ranges in every gear.

I know its clean, I've cleaned them several times. I've got a carbon arrow with a different brushes I attach to it. The arrow is small enough diameter I can get under the screen to clean the bottom and the top and sides I can see when brushing, all while flushing it with diesel until it runs clean to the back, run a flat magnet all around in there and make sure to get anything ferrous out of it.

Power steering is good whether its slipping or not, brakes are good too they'll hold tight enough to completely stop the tractor if its at an idle. If I open it up to higher RPM and brake it'll pull the engine way down, sometime it will go ahead and kill it and sometimes it will set there and slip with the engine bogged way down puking black smoke. I did check the charge pressure, service manual called for 15 psi minimum and it tested out at 25 psi. That was at an idle and not wide open or under any kind of load, its easy enough to drop it out of there I may do that once I get it back together just to rule that out.

When I split it this most recent time and took the torque limiter back apart, two of the bolts snapped off in the flywheel with about half a turn on the ratchet. They were torqued to 80-90 ft-lbs which is what the service manual called for. I'm replacing all of them when I put it back together, I'm wondering if that is related. Manual calls for red loctite to be applied to the flywheel threads and I cleaned the threads before installing the bolts, but something seems off with two of them just snapping instantly within half a turn.

Check the Charge Pump.

I got this thing back together yesterday evening. No change in how it behaves when running. What pressure should I be looking for on the top most test port title LUBE, the port below it tested out at 250psi.

I've got very little pressure on that LUBE port.