RTV x1100c Tranny Trouble

dtreid

Active member
New to me RTV x1100c. Will not rotate tires unless they are off the ground.
Took the HST apart and found one of the hst pump (valve block) plungers in bad shape. Replaced it with a new pump (valve block).
The motor valve block appeared to be in good shape.
Replaced both motor and pump valve plates with new ones.

Put things back together and it's no different than last time.

Put pressure gauge on charge pump and I'm getting 70psi that is in spec

Put pressure gauge on P1 travelling port and can only achieve 200psi.

Swapped the high pressure relief valve with another unit I have. No change.

Any tranny experts have an idea?
 

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aurthuritis

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valve block? that pic isn't a valve block? probably swash plates are scored and leaking. if the plungers on the pump or motor you have scores pictured would be the same
 

dtreid

Active member
Kubota parts calls this piece a valve block. Looks like someone took a grinder to one of the pistons...
The plates that the rear of the valve block rides against are both brand new. The old one was scored.
 

aurthuritis

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the valve blocks are a positive displacement set. if they are new and both the drive and driven are new then you should be able to rule out leakage. if the charge pressure is within spec then you can rule that out. if the swash plate brass plates are new and arent leaking you can rule that out. about all that leaves is the swash servo not moving the swash plate or leakage in the high pressure circuit.

i re read your post and noticed that you didn't replace the motor valve block? could that be the source of pressure leak???
 

dtreid

Active member
That's correct I did not replace the motor valve block. I could see no damage on it. I'm wondering about a stuck check valve or something similar....
 

aurthuritis

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to me the charge pressure seems at low side of spec?? am i correct? i think you have an internal leak. could it be the driven valve block? also what fluid are you using?
 

dtreid

Active member
Spec for charge pump is 62-120psi. This one was only about 5psi lower than my other unit that runs great. It has fresh kubota udt premium fluid in it
 

dtreid

Active member
Here is a pic of the old plates
 

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aurthuritis

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ok thanks. that is about what i thought ahat bout the charge pressure but that isn't your problem anyway. i would guess that the driven valve block or motor is leaking. those plates look scored and discolored to me
 

dtreid

Active member
The smaller plate was definately scored. The larger one doesn't apear to have any scoring, but they were both replaced with new ones anyway. There appeared to be the reamains of assembly lube in the tranny, but it was more like vaseline....assembly lube I've used dissolves in oil. I'm wondering if there could be some of that clogging a port somewhere.
 

aurthuritis

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i doubt it. if something was blocked on the high side there would be something broken internal. something is probably leaking internal.
 

aurthuritis

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there is a valve that i can't remember it's name. kinda works like a coast valve for when you let off of the peddle at speed. it is a high pressure bleed off to protect the pump and motor from overstress. have you checked that valve???
 

aurthuritis

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also have you checked the poppet valve that relieves pressure when the brakes are applied? if this valve is stuck open it would affect your pressure for sure.
 

dtreid

Active member
I swapped the valve that the brake runs with my other machine. No change.

I'll pull the coast valve out and have a look. Thanks for the suggestion.
 

aurthuritis

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i sure hope that fixes it for you. that would be much better than replacing the motor side valve block.
 
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