I have a 1992 Case 590 Turbo. When I start it in the mornings, it has lots of power like new. After about 1 hour of pushing dirt, it starts loosing power, forward is worse than reverse. When I let it sit for about 1-2 hours, is has power again until it gets hot again. I have changed the oil and filter in the transaxle and checked the suction screen. Is it loosing pressure from the pump in the torque converter? Why does it work cold but looses power when it's hot? Any ideas?
Do the engine rpms drop when it is losing power ? Did you clean both screens in the transaxle ?
Rpms don't drop. Is there a screen on the elbow going into the torque converter? I only cleaned the one going into the transaxle.
This image is in the service manual. #10 is the pick-up tube. Is #12 the filter you changed ?
Yes, I did change #12 as the filter. Does the #10 have a screen in it? I did check and clean the suction unit on the transaxle housing (the other end of #10).
@Tinkerer I don't think that you have the correct transmission here..... A 590 Turbo should be configured the same as a 580SK phase III - just with a little more horsepower. @Mikey7579 You need to carry out a stall test - see below for specific test details from a training manual - not a service manual. Note - when performing the torque converter test, the manual says only to do it only in Forward gear - Also carry out the test in Reverse - this should show a difference if there is a fault (ie worn plates or leaking seals) in the FWD pack. REV doesn't do the hard pushing work of FWD - it will usually still be in better condition.
What should I look for in the stall test? Should I do it when it is cold? That's when it has maximum power. After a couple hours, when it is hot, it won't even push one pile of dirt.
The stall test checks the efficiency of the transmission & hydraulic system by gauging the amount of load on the engine. The test should be carried out when at operating temperature, but you could compare the results from operating at cold & then hot. What you are looking for is a the difference of engine load between FWD & REV. This will tell you if the is a problem affecting ALL drive or just FWD. By the sounds of it you do have a pump/pressure problem, as they lose efficiency from cold to hot - as the oil viscosity thins. You will need to test the transmission pressures to confirm this. There are test ports located on the transmission control valve. There are two different types of control valve fitted to this transmission, does yours have a short steel oil line going across it? Also when the transmission is hot, does FWD take the same amount of time to engage as REV?