4020 Powershift Pressure test port adjustment

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I've searched all evening and can't find pictures or description of where exactly the test port is to test the transmission pressure on a 1967 4020 Powershift. I've found that with warm oil the pressure should be 150 psi (early models) to 160 psi (late models). I even found one place that said to turn it up further to 190ish for better performance. On my dash gauge it will peg far right when cold but after an hour in the field it will drop below the "safe" line so I'm likely looking to shim it up a bit to keep it in the operating zone. Operation of the transmission is still all normal, and I'd like to keep it that way. New Hygard oil, filters, and cleaned the screen this fall.

Which plug is my test port and which one hold the spring and shims I should possibly be adjusting?

Thanks
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What you see on the dash is the lubrication pressure. The trans. clutch pressure is another gauge only fitted on industrials units applications. (770 Grader, 760A scraper, etc...).

You need both gauges to be safe.
 
. The relief valve limits the maximum pressure and does do anything to maintain a minimum pressure .
The transmission pressure is dropping because the worn pump can not keep up with the seapage around old seals after the oil becomes thinner .
A new pump maybe enough or it may require chancing some seal swelling additive . If you don’t want to open up the transmission for freshening up.
 
(quoted from post at 11:37:26 01/23/19) Thanks, what number is that manual? I see the later serial number ones are cheaper for some reason.

John Deere AG publications says SM2039 is for 00000 (5 digit#) - 090999, 091000 - 200999
 
(quoted from post at 10:52:50 01/23/19)
A new pump maybe enough or it may require chancing some seal swelling additive . If you don’t want to open up the transmission for freshening up.

IIRC a lot of seals in powershift trans are metal so I think seal swelling additive will not be of any assistance to slow down internal hyd leak
 
I guess I should ask is there a problem?
Are some or all of the gears slipping?

On the left side (Direction of travel), use the port called "clutch", this the lube pressure, or better yet the pressure that is being supplied to you clutch / brake packs. If I remember correctly per my JD service manual you should have 160PSI.

On the right side (direction of travel) you have all the test ports labeled C1, C2, C3, B1, B2, B3, B4. These are the test port for each clutch / brake in the powershift trans. You will need a service manual (unless someone post) to know what clutch / brake goes with each gear.

Each gear should have 160PSI, if one of the clutch / brakes are low you run a risk of a gear slipping. Otherworld's, there is a oil leak in the clutch pack or planetary unit or he dive / driven plates are worn out much like mine were a couple of years ago.
 
I got that manual ordered SVCummins. Thanks

Hay Maker 2, what you've said makes perfect sense to me. That matches up with Forty20's picture too. He has his test port in
the plug by the "clutch" in the casting. Thanks.

No issues with transmission operation yet, but I'm looking to check these pressures and adjust the whole system up to that
160psi spec or figure out how to fund a Powershift seal overhaul before it is slipping and ruining more hard parts.

My clue that it might be on the low side is just the dash gauge that says "minimum pressure at 2200 rpm". When I see the needle
drop below that line after a few hours of work in the summer, it tells me with hot oil, it is dropping below that "minimum
pressure". So here I am, trying to do my job as operator!
 
I’m for sure that there were some leaks in my powershift, but the leaks were not my issue.
My clutch packs were just worn out. The drive plates, driving plates, and piston were just worn too thin. I could of increased the oil pressure, but that would of done nothing more than create bigger leaks. When the drive plates, driven plates, and pistons are worn thin there is not enough physical travel left in the drum for drive plates to clamp on to the driven plates, therefor gears were slipping.
I first resealed everything and thought I had my issues fixed, but it did nothing for me. When I disassembled everything I had several different mechanics look at the drive plates and driven plates and everyone said there was nothing wrong with them as they were not warped and the surfaces were not mated up. What everyone failed to do is actually measure the thickness of each plate.
What I’m getting at, is you can reseal everything and it may or may not fix anything.
Do you know if the clutch pack / planetary units were ever rebuilt?
 
No slipping here yet even with the gauge indicating low
pressure. Transmission has never been overhauled. It has
11,000 hours or so, so I am aware it is far from new.

I could be up against the same situation where it is just plain
worn thin, but I think it might also have some life left (or
continue operating fine) if supplied the correct pressure.
 
There are a lot of early 4020's power shifts still running with the original transmission parts..
 
Thinking about your issue last night and thinking about my issue a couple of years ago. I decided to dig through my service report (I document what I do so I have a record of it).

1. Placed 0 – 300 lbs. gauge on the “clutch” port below the inching peddle, gauge registered 160 psi. Pressure increased / decreased smoothly as the inching peddles was pressed or depressed.
2. Placed same gauge on the “PTO” port and tested with the PTO in the on position, gauge registered 160 lbs. It appears that the lubrication / supply pressure is well within its means.
3. Placed a set of seven gauges on the shift valve housing and measured supply pressure to each of the individual clutch / brake units in all gears. Consistently the C1 & C2 clutch packs had low pressure. C1 & C2 clutch pack was registering around 75 lbs. of pressure when used individually, but when you used a gear like 7th or 8th which uses both the C1 & C2 packs the pressures dropped to 50 lbs. The remaining clutch pack, C3 and the four brake units all tested out to 150 – 160 lbs.


What I am getting at, is even if you have the 160PSI on the port for the "clutch" you may still have a problem in the clutch pack or planetary.
You need to check each port and see the actual pressures.
Increasing the pressures will not help anything if there is a leak. The only think it will do is leak more.
 
(quoted from post at 08:57:06 01/26/19) Thinking about your issue last night and thinking about my issue a couple of years ago. I decided to dig through my service report (I document what I do so I have a record of it).

1. Placed 0 – 300 lbs. gauge on the “clutch” port below the inching peddle, gauge registered 160 psi. Pressure increased / decreased smoothly as the inching peddles was pressed or depressed.
2. Placed same gauge on the “PTO” port and tested with the PTO in the on position, gauge registered 160 lbs. It appears that the lubrication / supply pressure is well within its means.
3. Placed a set of seven gauges on the shift valve housing and measured supply pressure to each of the individual clutch / brake units in all gears. Consistently the C1 & C2 clutch packs had low pressure. C1 & C2 clutch pack was registering around 75 lbs. of pressure when used individually, but when you used a gear like 7th or 8th which uses both the C1 & C2 packs the pressures dropped to 50 lbs. The remaining clutch pack, C3 and the four brake units all tested out to 150 – 160 lbs.


What I am getting at, is even if you have the 160PSI on the port for the "clutch" you may still have a problem in the clutch pack or planetary.
You need to check each port and see the actual pressures.
Increasing the pressures will not help anything if there is a leak. The only think it will do is leak more.


"It appears that the lubrication / supply pressure is well within its means."

Just to be clear you are measuring "clutch apply pressure", transmission LUBE pressure is another thing altogether.
 
(quoted from post at 06:57:06 01/26/19) Thinking about your issue last night and thinking about my issue a couple of years ago. I decided to dig through my service report (I document what I do so I have a record of it).

1. Placed 0 – 300 lbs. gauge on the “clutch” port below the inching peddle, gauge registered 160 psi. Pressure increased / decreased smoothly as the inching peddles was pressed or depressed.
2. Placed same gauge on the “PTO” port and tested with the PTO in the on position, gauge registered 160 lbs. It appears that the lubrication / supply pressure is well within its means.
3. Placed a set of seven gauges on the shift valve housing and measured supply pressure to each of the individual clutch / brake units in all gears. Consistently the C1 & C2 clutch packs had low pressure. C1 & C2 clutch pack was registering around 75 lbs. of pressure when used individually, but when you used a gear like 7th or 8th which uses both the C1 & C2 packs the pressures dropped to 50 lbs. The remaining clutch pack, C3 and the four brake units all tested out to 150 – 160 lbs.


What I am getting at, is even if you have the 160PSI on the port for the "clutch" you may still have a problem in the clutch pack or planetary.
You need to check each port and see the actual pressures.
Increasing the pressures will not help anything if there is a leak. The only think it will do is leak more.



I think you and I are/were performing the same procedure for different reasons.


I DO NOT have 160psi lube/clutch pressure (according to dash, will now confirm through test port).

I DO NOT have any gears slipping (looking to keep it that way)


You DO/DID have 160 psi

You DO/DID have gears slipping


I'm just hoping to keep the pressure within spec as this transmission wears and keep the hard parts going as long as possible. If a simple shimming of the pressure regulating valve keeps me at 160psi then that's what I'm after! As Tim S said above there are still a lot of original Powershifts out shifting around, and mine is one of them. I'm doing this as normal/preventative maintenance, not necessarily as a repair.

I think we're all on the same page! The manual I got has lots of this info too. I'd recommend it to anyone.

Thanks
 

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