Last week I posted that I thought the sump screen may be clogged with many years of accumulated muck. As a result, I drained the transmission of what was fresh Hytran just put in a few days ago that had become a mixture of rust, oil, and water, and then started a procedure to backflush the sump screen.I fabricated a contraption from an air filter/regulator assembly that was gutted of its filter to use as a pressurized canister. Fittings were installed to connect to an air hose through a ball valve as a shut off, and connected its outlet to the passage way in the pump distribution block of the power shuttle between the sump screen and pump. This was done by removing a pipe plug in the casting which allowed entry into the passage. The canister was filled with kerosene and blown backwards through the sump and allowed to drain into a bucket. During this procedure, the torque converter was, also, drained. The contraption was removed, and the transmission was refilled with fresh Hytran. Upon starting the tractor, the pump pressure jumped to 90-100 PSI, and when the engine was revved up, the pressure would increase to 140-160 PSI. All of these pressures were within the Ford specification. Afterwards, I decided to test the function of the shuttle, so the tractor was jacked up and set on stands. Then I began to move the lever on the shuttle to forward and backward. Success! The wheels rotated in the corresponding directions. In a few minutes, however, the shuttle stopped functioning and the pump pressure had fallen off to about 20 PSI. If the engine was stopped and restarted a few seconds later, the pressure would jump to about 90 PSI and quickly drop back to about 20-40 PSI. When disconnecting the cooling return line from the radiator, there is only a dribble of flow where there should have been between 2 & 4 gallons per minute. CONCLUSION: Since the pump is a gear pump, it just can’t work at one moment and not the next, then start working again. I’m thinking that the relief valve and the bypass valves in the distribution block are stuck open or very sluggish due to the rusty residue that has probably been deposited in the bores. The next step is to remove the hex plugs at the bottom of the distribution block and see if the plungers, springs and bores can be cleaned through the access hole that is in the bottom of the bell housing. Has anyone had an experience similar to this?
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