We recently bought a 10K and it does not always shift into gear, that is the selector is moved out of neutral and the machine will not move. I spend a fair amount of time troubleshooting a few days ago and came up with the following information; The filter and magnetic filter look good, it was serviced by Cat 70 hours before we bought it. The shift linkage seems to be working fine and when it does go into gear it will go into all 3 F&R correctly. Trans oil level is up. Measuring some pressures; the Transmission Pump under the seat (Test Port K) measured 315 psi with governor set to minimum. The pressure at the Speed Clutch (E) was 340 psi and at Direction Clutch (F) it was 285 psi with the governor above the detent (maybe 1/3 of maximum). When it does not shift into gear, the Speed Clutch dropped to 90 psi and the Direction Clutch dropped to zero. When it does not go into gear, test port K sometimes has a “fluttering” pressure making the needle of the test gauge rapidly fluctuate 50 psi around 340 psi. I can feel it in the gauge and I can hear it. I have noticed shifting it very quickly into gear, the pressure does not drop as much and it will consistently go into gear. Shifting it slowly, the pressure (K) drops to 70 psi and it will not go into gear. If the pressure stays above 100 psi while shifting it will consistently go into gear. Other note worthy information; Shifting from gear to gear, the same occurs, shifting slowly will allow the pressure to drop too much and it will not go into gear. Shifting very rapidly the pressure does not drop below 100 and it will consistently go into the next gear. If (big IF there) I am understanding the system correctly, the Pressure Differential and Safety Valve is what drops the pressure during a shift and is likely the avenue I should look into? Is the fluttering likely from the Modulation Valve because the Pressure Differential and Safety Valve is misbehaving? I have the manual but have not discovered where the Pressure Differential and Safety Valve is physically located- I assume under the trans cover where ports E and F are? Any advice on tearing into the valve or other things I should look at first would be greatly appreciated.
Hey there I went through a similar situation on a D6D 4X after it got up to operating temperature it would not shift into 2nd Forward all other shifts worked great after lots of troubleshooting and frustration I replaced the trans pressure control valve the top valve when you take the trans cover off (under the floor pan). I replaced it with after market and the problem was fixed so I thought It reappeared a couple hundred hours and so long story short I replaced every spring in the valve assembly with genuine Cat springs and havent had a problem since. What I am trying to say is that you can replace all the springs easily and inexpensively and it might fix your problem when doing this make sure every small orfice is clean some of the poppets are pretty small. good luck
It sounds to me your trans is not coming up above initial pressure when it will not drive. You need to check the spools are adjusted right. The ends line up with machined surfaces on the valve when correct. Shift around F or R 1 should be the position, can't remember but could figure it out if there. Then the linkage under the cover is adjusted to flush the spool ends. If not correct trans may be acting like a start up in gear and staying in initial. Later Bob
Great, thanks for the info guys. I will check the spool adjustment before tearing into the valve.
Bob, it looks like you nailed it. The speed spool was about .030" off. The direction spool was only about .010" off, but I adjusted it anyway since I was in there; but I can't imagine it is that finicky... but maybe it is by the time you factor wear in everything between the selector and the spool. Tested the machine for 10 minutes or so and never got it to fail, when never before would it go that long without failing. Thank you very much for the help Bob!