QuestionQUESTION: We have a Case 2290 with a hydraulic problem. The hydraulic filter and transmission lights come on unless the range is in second. We checked the suction screen and it is clean. Removed the charge pump and replaced the wear plates, they had hot spots on them. Disassembled the power shift transmission and found worn friction plates and broken piston return springs. Installed new piston seals, friction plates, separator plates, springs, sealing rings, and the plastic tubes behind the valve body. The problem seems to be the same. The transmission seems to load the engine and would make it stall if we did not step on the inching pedal. This happens when the gear transmission is in neutral. The charge pump pressure is within specification. I have not checked the clutch pressures because I had to go out of town. I am an experienced technician with no brand specialty. If you have an idea which direction I need to go when I return home I would be very appreciative. Thanks for any time you may be able to put toward my problem. Michael
ANSWER: The filter light is supposed to come on if there is low charge pressure, but since your charge pressure is good, the only other causes are a bad pressure switch or shorted wire. I don't quite understand how the light could only come on in second. It will be impossible to guess what is wrong until you check all the pressures when you get back. If the transmission is trying to stall the engine, you have one or more pilot spools in the powershift control valve that are stuck. This will cause it to labor or stall the engine because it is trying to run in two powershift speeds at the same time. The spools will have to be removed and cleaned, and any rough spots polished until the spools slide freely in the bores.
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QUESTION: The filter lights would only go out if the transmission was shifted into second range. I removed, polished and reinstalled the spools. The lights now stay off. The C3 clutch is being applied when in reverse. I believe it is in the valve body. The C3 clutch is not being pressurized in low, leading me to rule out an internal leakage past the sealing rings on the hub. All of the spools move freely. I did not see any issues with the valve body when it was off. I must be missing something. How do you determine the flow of oil through the valve body. Is that information in the factory manual. I only have an I&T manual right now. Thank You for any advice you can provide. Michael
Answer As you probably already know, C2 and C4 are the only clutches that should have pressure when in reverse. In powershift 1, only C1 and C2. In powershift 2, only C1 and C3. In powershift 3, only C2 and C3. Pressure should be 200-210 psi. If a gauge shows pressure to C3 in reverse but not in powershift 1, then obviously you can rule out a pilot spool problem. A leaking check valve in the control valve, a blown gasket, or a crack in the valve housing could allow oil to the wrong clutch. I have seen the wrong control valve gaskets installed or gaskets installed incorrectly so that the holes do not line up or are not in the right place. If there was broken or leaking seal rings in the oil distributor, oil pressure would be low to certain clutches. A factory manual should have a hydraulic schematic that shows the oil flow. I think the valve should be removed and inspected, and check the gaskets carefully to make sure the oil holes are in the right places. New gaskets should always be installed when assembling, and I always compare the new gaskets to the old ones to make sure they are correct.
