JD 2955 xmission and PTO pump pressure.

I have PTO and transmission pump pressure problems on a 2955 green and yellow lemon. We were getting pressure drops at the PTO port that we couldn't explain. We split the tractor and had the PTO clutch and transmission pump checked out at a John Deere place to be rebuilt. I was told to get a #8 o ring fitting for the pressure gauge. I looked at the shifter cover and saw 2 #8 fittings. I unscrewed one and was absolutely unprepared for what happened next. The cap disappeared and 2 springs popped up in its place. I later heard something touchdown somewhere behind me. Went back to the John Deere place for a cap, o ring and four shims. Of course I have no idea how many shims were there originally. We made one and the pressure still is not as high as we would like 160 to 170 PSI. Each shim adds 2 PSI and it is slightly below 150 PSI. Is 2 PSI normal for each shim or should should the pressure change be useful?
Hoader:

You probably still have an internal
hydraulic leak, which is bleeding off
charge pressure. Could be a cracked
or leaking tube,which while very
common on the 40 series, still shows
up on the 50-55 series tractors.
Could also be a weak charge pump,
leaky pto valve,steering valve, or in
the hi low valving

Has hyd filter been changed lately & hyd oil sump screen checked/cleaned? Another thing to check is be sure filter relief valve isn't stuck open

Why did you not look in the parts book first to know what you were getting into ?

(quoted from post at 14:50:50 04/15/20)
Has hyd filter been changed lately & hyd oil sump screen checked/cleaned? Another thing to check is be sure filter relief valve isn't stuck open

Click to expand...

We cleaned the screen and installed a new filter after bolting the transmission to the rear end. It has fresh oil too. I will check that valve soon and tell you what I find.
Thanks hoader

+

Do you want the official answer or the truth?

Ok, The John Deere shop went through the pump and pto clutch and I believe they are fine. Now these other things, how can I pinpoint where the leak is? We inspected the tubes and inserted the o rings/ I didn't use magnifying glasses to look for cracks. We have had a tube blow out in another green and yellow lemon. I hate to remove all the tubes and deal with the o rings that are such a painus in the ain*. What could happen with the hi-low? That has not been touched. Is there a way to cut off oil flow to the hi-low and then check pressures? I will spend more time with the manual and give me more hints as you think of them.
Thanks hoader

High pressure internal leaks can be identified by utilizing an infrared thermometer to checked for warmest external hyd component. Does tractor have a frt end loader? If so what type valve controls FEL(scv or ind)? With 3 pt raised engine operating at 180+ look in hyd fuller hole behind seat for moving oil. One can remove shift cover & apply compressed air to IPTO & hyd hi-lo supply tubes & listen for air leaking in/around tubes. Hyd hi-lo & pto clutch drum sealing rings could be leaking causing hyd problems.

Very good diagnostic procedures are the KEYS to solving closed center hyd problems!!!!!!

(quoted from post at 01:58:04 04/15/20) I have PTO and transmission pump pressure problems on a 2955 green and yellow lemon. We were getting pressure drops at the PTO port that we couldn't explain. We split the tractor and had the PTO clutch and transmission pump checked out at a John Deere place to be rebuilt. I was told to get a #8 o ring fitting for the pressure gauge. I looked at the shifter cover and saw 2 #8 fittings. I unscrewed one and was absolutely unprepared for what happened next. The cap disappeared and 2 springs popped up in its place. I later heard something touchdown somewhere behind me. Went back to the John Deere place for a cap, o ring and four shims. Of course I have no idea how many shims were there originally. We made one and the pressure still is not as high as we would like 160 to 170 PSI. Each shim adds 2 PSI and it is slightly below 150 PSI. Is 2 PSI normal for each shim or should should the pressure change be useful?
Hoader:

Click to expand...

We may be getting side tracked here. Adding shims to the pressure regulator seemed to make such a small difference in pressure. We had 135 PSI with no shims and 155 PSI with 4 shims. Stacking more shims is beyond the recess of the cap to hold the shim in alignment. I dare anyone to try is without having shims flying all over the shop. Could there be something in the valve housing or a weak spring causing the problem? 4 shims is almost 1/2 inch additional compression and results in only 20 PSI change.

IIRC 155 psi for trans pump operating pressure should be sufficient for hyd hi-lo & IPTO operation.

(quoted from post at 20:30:56 04/17/20)

(quoted from post at 01:58:04 04/15/20) I have PTO and transmission pump pressure problems on a 2955 green and yellow lemon. We were getting pressure drops at the PTO port that we couldn't explain. We split the tractor and had the PTO clutch and transmission pump checked out at a John Deere place to be rebuilt. I was told to get a #8 o ring fitting for the pressure gauge. I looked at the shifter cover and saw 2 #8 fittings. I unscrewed one and was absolutely unprepared for what happened next. The cap disappeared and 2 springs popped up in its place. I later heard something touchdown somewhere behind me. Went back to the John Deere place for a cap, o ring and four shims. Of course I have no idea how many shims were there originally. We made one and the pressure still is not as high as we would like 160 to 170 PSI. Each shim adds 2 PSI and it is slightly below 150 PSI. Is 2 PSI normal for each shim or should should the pressure change be useful?
Hoader:

Click to expand...

We may be getting side tracked here. Adding shims to the pressure regulator seemed to make such a small difference in pressure. We had 135 PSI with no shims and 155 PSI with 4 shims. Stacking more shims is beyond the recess of the cap to hold the shim in alignment. I dare anyone to try is without having shims flying all over the shop. Could there be something in the valve housing or a weak spring causing the problem? 4 shims is almost 1/2 inch additional compression and results in only 20 PSI change.

Click to expand...

Relief valves only limit the pressure to maximum level. Relief valves do not affect pressures under it's set point.
If the pump can not keep up with demand, seepage and leaks . No amount of relief shimming will take the pressure over 155psi.

I hesitate to suggest it.... If leakage is past old worn, shrunk and hardened seals and gaskets around the high/low, PTO clutch and PTO brake.
Before tearing it all apart, maybe a dose of that Lucas seal swelling snake oil maybe worth a try ?


Don't intended to hijack your thread. A minor version of your challenges going on here too.
The hydraulic independent PTO control valve on my 1640 has been seeping oil and rust proofing the center section of the tractor.
The low transmission oil pressure light came on so I replaced the gasket R234266 .
However I had a stunned moment and realized that I did not order two of the fat little O'rings L36237 at the same time. They were on a different parts diagram and did not double check all the info as should have been done.
Will have to take the PTO control valve off again today and replace the O'rings . They were so shrunken and so hard. Have to wonder if the wrong oil had been poured into that tractor at one time ? The rockshaft piston rings are also seeping , so there is a pattern there.
The O'rings also blew out of the power steering a few years ago and rust proofed the back half of the tractor and myself. They too appeared damaged.
There may have been some GL-5 gear lube dumped in there decades ago. Flushed the system twice since purchasing however the damage is done.
Will double check the transmission low pressure switch too for leakage. It is in a nearly inaccessible location unless the entire top is lifted off the transmission.

(quoted from post at 10:13:03 04/18/20)
I hesitate to suggest it.... If leakage is past old worn, shrunk and hardened seals and gaskets around the high/low, PTO clutch and PTO brake.
Before tearing it all apart, maybe a dose of that Lucas seal swelling snake oil maybe worth a try ?

Don't intended to hijack your thread. A minor version of your challenges going on here too.

Click to expand...

b&d
IIRC on hyd hi-lo & IPTO clutch the seals are metal no rubber.

(quoted from post at 15:21:47 04/18/20)

(quoted from post at 20:30:56 04/17/20)

(quoted from post at 01:58:04 04/15/20) I have PTO and transmission pump pressure problems on a 2955 green and yellow lemon. We were getting pressure drops at the PTO port that we couldn't explain. We split the tractor and had the PTO clutch and transmission pump checked out at a John Deere place to be rebuilt. I was told to get a #8 o ring fitting for the pressure gauge. I looked at the shifter cover and saw 2 #8 fittings. I unscrewed one and was absolutely unprepared for what happened next. The cap disappeared and 2 springs popped up in its place. I later heard something touchdown somewhere behind me. Went back to the John Deere place for a cap, o ring and four shims. Of course I have no idea how many shims were there originally. We made one and the pressure still is not as high as we would like 160 to 170 PSI. Each shim adds 2 PSI and it is slightly below 150 PSI. Is 2 PSI normal for each shim or should should the pressure change be useful?
Hoader:

Click to expand...

We may be getting side tracked here. Adding shims to the pressure regulator seemed to make such a small difference in pressure. We had 135 PSI with no shims and 155 PSI with 4 shims. Stacking more shims is beyond the recess of the cap to hold the shim in alignment. I dare anyone to try is without having shims flying all over the shop. Could there be something in the valve housing or a weak spring causing the problem? 4 shims is almost 1/2 inch additional compression and results in only 20 PSI change.

Click to expand...

Relief valves only limit the pressure to maximum level. Relief valves do not affect pressures under it's set point.
If the pump can not keep up with demand, seepage and leaks . No amount of relief shimming will take the pressure over 155psi.

Click to expand...

So you are saying the transmission pump is being maxed out and that is why adding shims is to increase pressure is ineffective? I don't know how much seepage and leaks there are. We were hoping for 160 to 165 PSI to make certain everything enguages properly. I hate splitting the tractor and am tired of it. I am already bias since this is his second 29 series tractor we split multiple times.

I will try the snake oil! :wink:

(quoted from post at 01:47:21 04/21/20)
I will try the snake oil! :wink:

Click to expand...

I have driven the tractor and noticed a few more things. 1) the pto clutch had aftermarket disks in the clutch pack. When engaged, the piston bottomed out before applying sufficient pressure for the torque available. Either the pto brake or the clutch has a pressure of 145 psi (cold) to 125 psi. There are radical changes in pressure when shifting the rabbit turtle. No difference using the steering wheel. Does drop when using 3 point hitch to 80 psi and snaps back up.
We put the pressure gauge in the transmission lube circuit. There were times the pressure would drop to 0 and for longer than I thought reasonable. I also didn't see a pattern behind these pressure drops. Pressure range goes from 0 to 110 psi. My guess is an average of 50 psi.
We had the gauge in the pressure port from the transmission pump and as before, ranged from 125 to 145 psi. Yesterday there were a couple problems shifting into rabbit where I had to finesse the handle for it to engage properly. The 3 point hitch didn't pick up the plow a couple times. I had to stop and wait. Same thing with flipping the plow. Engine RPMs were 2400 or normal PTO speed. The remotes gave me more trouble than the 3 point hitch. Today I went to plow and (cold) I couldn't flip the plow. Then I tried to turn and the power steering was jerking as if the pump was starved. The reservoir should have been full running the engine at 1700 RPMs for over a minute. I parked the tractor.
Early history of this tractor. It was involved in an electrical fire. The wiring harness and dash and starter was replaced. I don't know of anything else. The damage was light but maybe some valve got compromised.
Thanks hoader