D6c Trans/steering clutch pressures

[D6c10K]

Started trying to diagnose the pressure issues on my 6c. Steering clutch pressures are below spec at low idle and above spec at high idle.
The steering clutch pistons have been checked & resealed a while back so I don't think that's the problem. (unless I did something wrong)

I pulled the trans pump to see what shape it's in....it looks brand new inside and check dimensions are in new spec.

Thinking the next thing would be to check out the sequence relief valve. Book says to drain bevel gear case & torque converter before pulling valve off. Is that really necessary? Oil level in bevel gear case is well below the valve and torque converter shouldn't have oil that high either. Don't want to drain everything if I don't have to, but don't wan't to loose gallons of oil on the floor either.

Is it necessary to have the valve bench checked for correct flow/pressure? Don't know if anyone at the Cat dealer is old enough to have ever seen one.

 

[Mobiltech]

Is it a power shift and what is the serial number. Did you check your pump pressure at the filter housing. I would do that first. It should be about 350 or so at high idle.
You don't have to drain oil to remove the sequence relief valve.

 

[Old Magnet]

Depends on s/n. Early 10K1-5983 pump pressure is 275psi min, 310psi max.
10K5984-up is 315psi min, 350psi max.

The steering clutch hydraulic control valve controls pressure to the steering clutches. You can check free length of the springs and length under test force based on specifications.

 

[Bob/Ont]

If you have a powershift trans check the tube at the RH rear of the trans just under the cover, the orings blow off of it and cause pressure drop and torque overheating. Also when resealing the release pistons did you check the bevel gear shaft bearings?
Later Bob

 

[D6c10K]

Is it a power shift and what is the serial number. Did you check your pump pressure at the filter housing. I would do that first. It should be about 350 or so at high idle.
You don't have to drain oil to remove the sequence relief valve.

power shift 10K10639
pressure at filter: low idle=300 high idle=410 (specs are 315/Low & 350/Hi)

Pressure at "K" port (clutches engaged) low idle=330 high idle=385
(LH or RH disengaged) low idle=drops to 220 comes back up to 265 High Idle: 375
(Both disengaged) low idle=225 high idle=375

clutch pressures at rear ports (w/clutch disengaged):
(LH & RH same) low idle=drops to 220, comes back up to 265 high idle=375


Summary:
Low idle pressures are too low & high idle are too high..... Checked the pump thinking that someone had upped the pressure to compensate for a worn pump.

low idle readings varied some due to rpm variations....didn't have a tach handy.
(Definitely would help if I had a test gauge set...only had one gauge to work with)

Anyone have Hi/Low idle speed specs????....can't find them in the books.

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The steering clutch hydraulic control valve controls pressure to the steering clutches. You can check free length of the springs and length under test force based on specifications.

I was thinking Sequence valve since pressure at both the filter & "K" port are out of spec.
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If you have a powershift trans check the tube at the RH rear of the trans just under the cover, the orings blow off of it and cause pressure drop and torque overheating. Also when resealing the release pistons did you check the bevel gear shaft bearings?
Later Bob

Not sure which tube you mean...Inside under the top cover?
Torque hasn't shown any heating problems.
I did put in new bevel gear bearings and replaced the bearing cages because there was a little wear where the clutch seals run.
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[Bob/Ont]

I know those pressures are not right on spec but the machine should steer okay. Pressure drop is more than I like to see but not too bad, looks like someone shimmed up the modulating relief spool to get more pressure. To find the tube I mentioned take the top plate off the trans and start it up, look for oil spraying out of it in the back corner, this is the tube taking the oil into the pressure control and selector spool valves. If everything is okay check the adjustment of the steering linkage rods.
Later Bob

 

[D6c10K]

.....check the tube at the RH rear of the trans just under the cover...

Pulled the top cover....found the tube you're talking about. Looks easy to replace the seal if that ends up being the problem.
Can I start the tractor with the top off the trans?...or will it give me an oil bath?

I see there are a couple of more tubes on the trans lubrication relief valve (lower front of the trans) that could cause leakage problems too.

 

[Bob/Ont]

Yes just keep your head back out of the line of fire. It will blast a shot of oil up on start up and on shut down or shifting. Just be careful to keep dirt out.
Later Bob

 

[D6c10K]

Popped the top of the trans and started it up to see if the tube at the right rear was leaking.
Shot a video while running....don't see any leakage at the tube. Control valves flow some oil out the ports in the top of valve bodies...I'm guessing that's normal?

https://www.youtube.com/watch?v=8S9VwCYyvsY&feature=youtu.be

Pulled the sequence relief valve and disasembled it...nothing obvious wrong. The springs are just a small amount shorter than book spec. If I replace the springs what's the best way to readjust the pressures? Can it be bench checked or is it just trial and error running it on the tractor?