Lull 6k-34 with ZF Tranny loss of oil pressure and no movement

[swampu]

I bought an old 6k lull with a zf transmission. It worked for about two weeks and quit. I changed the filter, and filled and refiilled several times to make sure it was clean. Yesterday I pulled the transmission to try to figure out why I'm not getting but only 15 lbs of pressure at the control port on the valve body. The oil pump looks good, is there anything else to check. I can't find a part number on the torque converter to order another one. Is that a typical napa part? Any help would be appreciated. Thanks

 

[Vetech63]

There is plenty of things to check, but it should have been troubleshot before the transmission was pulled. I'd be looking at the declutch system first.

 

[swampu]

Yea I probably jumped the gun but I just knew it was that oil pump. Now that it's out the oil pump looks fine. I'm going to clean it up and probably try to find a new torque converter and put it back together. I don't understand the declutch system. I saw that it affected the gear solenoid operation, I replaced 3 of the 5 solenoids because they were dead. I made sure the valve body was clean and functioning. I unplugged the computer and taped into the power to the solenoids wires to control which ones were operating to try to find one gear, forward or reverse to no avail. That's when I checked the pressure at the control port and got the 15#.

 

[tractormech]

I seriously doubt that you even need a torque converter. Some 6K's have a electric shift "computer" that the shifter signals to operate the solenoids on the transmission. The 15 lbs is lube pressure and it's constant- it the engine is running it's going to have lube pressure automatically. What serial number do you have? I'd put the transmission back together and back in machine and start fresh. The converter provides a mechanical link to the charging pump from the engine but doesn't control clutch pressure. There's a parking brake pressure switch and a declutch switch too- and a bad proximity switch on the boom can shut it down too. Some will lock out everything but low gear and some will be completely out of gear. Check that too.

 

[swampu]

Tractormech you hit the nail on the head. The Serial number is 97x12n21-365, it's a 1997 with a 3wg-100zf transmission. Since I pulled it out I inspected the oil pump and it's fine, the torque converter is like you said probably fine. I did take the valve body off again (previously I had another mechanic install the valve body after getting it cleaned out and replacing parts) When he installed it he had the two outer gaskets installed in the wrong order. I'm pretty sure that's the problem. It was an honest mistake I'm sure but it was happy for me because I didn't have to buy a new pump or torque converter. I also cleaned it up real good and will hopefully have it back in the machine monday. I will check the other items but right now I've disconnected everything from the solenoids and basically am running 12 volts to the solenoids that make the machine go forward, just to see if I can grab a gear. Once I know the transmission works than I'll start working on the proximity sensor and other items that may be affecting gear workings.