Long time listener, first time caller. Appreciate any pointers
D6H s/n 9KJ01130 , 9189 hours
This has been an on and off project for the last 6 months , now busy season is over we will be able to dedicate a some uninterrupted time to this machine.
Original issue- 200 hours ago, machine would not move. Found the two pump couplings to scavenge pump had failed (3E-4880 ) pulled the shaft and found the pump had locked up. Oil level okay, no operator complaints previously. Drained fluid, flushed system, new screens and filters installed, new pump and couplings. Machine ran another 6 months. (did not test any pressures at this point of installing new pump)
Second issue- machine stopped moving, found failed couplers again. Pump did not "feel " correct spinning over by hand. Pulled axles, dead loaded machine back to the shop. Pulled pump, opened it up, scaring internally, looked like pump was run dry. Fluid level adequate both by dipstick and seemed the correct volume came out while draining the machine.
At this point, opened up the transmission back cover and looked around, physically saw clutch plate and friction disc failure. Pulled trans . No obvious rags or foreign items in the oil sump.
Installed rebuilt trans, installed new pump, dumped oil in top of pump prior to starting, new filters, screen fluid etc. Started up dozer with gauge attached.
0 psi on port D (trans lube pressure)
Machine will start and move but did not move it around it much after saw 0 psi. checked with a 0-10 gauge and needle does not move. unhooking the gauge from the hose, fluid does not come out unless you high idle, at that point only a small amount , which you could hold back the fluid with your finger. I will note, that the pressure test port is slightly different than the service manual photo. - see photos-
Opened up and visually inspected the torque converter relief valve and priority valve, no visible damage. Pulled the screen and magnet below the scavange pump and it was still like new.
Big picture thought - it seems we are not getting adequate fluid to the transmission pump and that caused the original failure , low lube pressure causing the transmission failure.
Appreciate any thoughts on where to look next.
D6H s/n 9KJ01130 , 9189 hours
This has been an on and off project for the last 6 months , now busy season is over we will be able to dedicate a some uninterrupted time to this machine.
Original issue- 200 hours ago, machine would not move. Found the two pump couplings to scavenge pump had failed (3E-4880 ) pulled the shaft and found the pump had locked up. Oil level okay, no operator complaints previously. Drained fluid, flushed system, new screens and filters installed, new pump and couplings. Machine ran another 6 months. (did not test any pressures at this point of installing new pump)
Second issue- machine stopped moving, found failed couplers again. Pump did not "feel " correct spinning over by hand. Pulled axles, dead loaded machine back to the shop. Pulled pump, opened it up, scaring internally, looked like pump was run dry. Fluid level adequate both by dipstick and seemed the correct volume came out while draining the machine.
At this point, opened up the transmission back cover and looked around, physically saw clutch plate and friction disc failure. Pulled trans . No obvious rags or foreign items in the oil sump.
Installed rebuilt trans, installed new pump, dumped oil in top of pump prior to starting, new filters, screen fluid etc. Started up dozer with gauge attached.
0 psi on port D (trans lube pressure)
Machine will start and move but did not move it around it much after saw 0 psi. checked with a 0-10 gauge and needle does not move. unhooking the gauge from the hose, fluid does not come out unless you high idle, at that point only a small amount , which you could hold back the fluid with your finger. I will note, that the pressure test port is slightly different than the service manual photo. - see photos-
Opened up and visually inspected the torque converter relief valve and priority valve, no visible damage. Pulled the screen and magnet below the scavange pump and it was still like new.
Big picture thought - it seems we are not getting adequate fluid to the transmission pump and that caused the original failure , low lube pressure causing the transmission failure.
Appreciate any thoughts on where to look next.
