D5C powershift problem

[Rotgut]

Good afternoon,
My '94 D5C is having an unusual problem-
I have 1st, 3rd and 3rd, foward and reverse. I have clean fluid and filter, up to operating temp and all pressures at low and high idle are within spec as per the service manual.

I pulled and disassembled the valve body and found two things, a small strainer/orifice was dirty and where there are three small holes in the valve body two are threaded and one has a setscrew in it. The manual does not mention these but the parts book says a quantity of 2. Hmmmmm....

I can reach down to the clutch discs/ plates and feel freedom of movement there ( no oil pressure I know but nothing is jammed)

 

[Rotgut]

You can see the three holes near the bottom and to the right of center on the pic.

 

[Rotgut]

Clean inside....

 

[Cmark]

Not quite sure what the problem is. Do you mean you've lost second in fwd and rev?
Anyway, seeing as you're into it this far, before you install the valve you should put air pressure to your clutch packs to see if you have any leaks. Use a blow gun with a rubber cone tip. You should be able to make the pistons move with 100psi.

 

[Dave Neubert]

The quantity 2 could mean that it takes 2 for the valve not necessarily 2 in that position. I agree with CMark did you lose 2nd only

 

[Rotgut]

This is what is throwing me, in the second gear detent position ( foward and reverse ) the machine goes to third. Second is gone but not like I lost it, more like it has been replaced with third. All pressures remain consistent throughout the shifting process, there is no dropoff of pressure like the seals are blown on the number 4 clutch....if second was just gone and pressure dropped off while in second the problem would be obvious. Another strange thing is that while I am in the second gear detent, the machine is actually in third and when I shift to the third gear detent the pressure drops off and modulates back in just like another shift should and it remains in third gear. Weird, huh?

 

[Rotgut]

I really, really do not wanna have to pull the tranny as we are trying to wrap up a three year project ( side work, I am not some big company ) and I figured this is the place to ask. I have been reading this forum for years but cannot find this particular kind of problem. BTW, when Cat tells you to rig the valve out as it is 75 pounds listen to them, that sucka is heavy and in a bad spot!

 

[Rotgut]

Cmark, good advice. I will make that happen!

 

[Nige]

Speed selection linkage adjustment perhaps...?

 

[Nige]

Can you provide some context as to how the problem developed. Got worse over time, or suddenly from one day to the next, etc. Have you acquired the tractor recently or has it been with you for a while..?

 

[Rotgut]

Nige,
I reviewed the linkage adjustment for my machine, it is just a morse cable setup with the detents in the control valve acting on the selector spools themselves. There are no detent points on the shift lever so I suppose that any adjustment is just to make sure the spool gets to the detent.

I have owned the machine for a number of years....every once in a while when going from 1st to 2nd it would seem to miss 2nd but this is a new and sudden problem that came on last week. Dozer runs just fine in first and third but i wish third is the one that went away!

 

[Dave Neubert]

I would think it has to be in the valve' have you tried putting air to 2nd yet to see if it engages. have you removed the spool to see if it is broken. 40 years of working on these i have never run into this. It would be great if you could swap that control valve with another one

 

[Dave Neubert]

Can you provide a serial number I can stop by Iron Peddlers and see if they have a valve and check those holes

 

[Rotgut]

Dave, completely disassembled the valve, nothing out of sorts except that setscrew missing and I am not even sure what it does or if it even requires two.....parts book says a quantity of two. Have not tried the air yet, this is a side gig so I won't get to that until Friday probably.

Serial is 6ZL00200

40 years huh, yay!