Farmall 400 Hydraulic pump leaking bad! (long story)

Redturbo

Member
Its the same tractor that I had the power steering motor issue with last week. Couple years ago I brought this tractor from an older gentleman that was done with his acreage life style & moving to town. Farmall are not very common in Alberta for the most part. This one has a loader, live hyd's, power steering, 3pt hitch. Big upgrade for summer time chores around the farm yard compared to the Super W6.

Driveway is 900ft long, purchased a land plain to grade the gravel driveway & it sure works good. Noticed oil coming out the dipstick tube, its hyd oil. Back into the shop & take off the distributor & the pump. To my surprise find shim stock wrapped around the shaft tried to keep the worn out gear on. So need a new pump & get one ordered up. Notice the camshaft gear is also loose. My luck, the camshaft gear is loose because the key way is augered out. Strip down a SW6 parts tractor for a camshaft, couple gears, etc. Get the engine all back together & running with no leaks.

Now for some reason the hyd's are loading up the engine. Sent the priority valve away to Steel Ranch for him to install new pieces. Reinstall & its still the same, took apart the 3 spools thinking that was the issue. By now have lost interest in this tractor.

Tired of looking at in the shop, so I got rid of the IH hyd parts other than the new hyd pump & steering motor. Installed brand new single spool valve, priority valve to supply motor & spool. Washed the tank out, plumbed the system so the pump supplies the priority valve first. It sends 3gpm to the steering motor, 9gpm to the spool which is running the 3pt. Get engine running & the seal at the distributor is leaking hyd oil out. Replaced the seal, I know its only for case pressure. Not system pressure. Hoping was crappy seal from new? Well that didn't fix it, oil started leaking seal in about 5 mins or so. Anybody run into this issue? Cant be 1 hour of run time on this brand new pump. Warranty is long gone as its over the 1 year old. Warranty isn't my issue, I have the feeling if get another new pump will have the same problem again. Anybody see what Im missing? The priority valve has a relief, spool has a relief also. Thanks, Scott.
 
The issue is particles from the surgery getting into the safety regulator valve, causing the new pump to be on demand all the time. There is a
screen on the orifice, and possible collapse plugged up. Part #10 in the diagram. Jim
The valve
 
All the IH parts are gone, except for the hydraulic pump on the engine. Had to used the stock cast tank as it supports the fuel tank, steering, sheet metal. The 3 IH spools are gone, the safety regulator housing is also gone.
 
Then you may have no pressure control system and pressures can exceed 3000 PSI (twice the expected pressure, and destroy things. it must be an open
center valving (letting the oil flow back to the reservoir with no restriction) The priority valve must be the first thing the oil sees coming out of
the pump. Then a pressure regulator (might be built into a valve, but must be present), then two way open center valve/s with return to reservoir, then
cylinders. Jim
 
New Pump
mvphoto57117.jpg
 
Constant volume priority valve. Says its set at 1500 psi. 3gpm goes to the steering motor. 9 gpm goes to the spool
mvphoto57118.jpg
 
This the steering motor, supply comes from the priority valve, return goes to stock location to bottom tank.
mvphoto57127.jpg
 
Jim, hopefully the pictures will make sense of what I have done. Thanks for replying, do you see something wrong with the system?
 
Think I might have figured out the issue by re-reading you message couple times Jim. The spool relief is set at 2000 psi from where ever its built. Think I have most of the IH manuals. Read the hydraulic couples times, noticed the spec for the pump is 1200 to 1500 psi. Never thought much of that, then the light bulb went on. Whatever the pressure the spool is set at is higher than the pumps rating! Going to pick up some gauges tomorrow & adjust the relief in the spool down below the spec of the pump rating. I will update once I know more.
 
Most steering torque generators (the system you have) operate on 350 to 500psi. Check how much yours is rated for, or as good, when you get the
valve pressure regulator down to 1400 or so, reset the reguolator on the priority valve to 350 and see how well it works. If just fine, leave
it. if weak, increase it till it works well, but not to exceed the rating of the torque generator. There still could be a leak issue if the
existing seal has been damaged. What is being used as a vent on the reservoir? it needs to be vented to allow for expansion when heated up, and
or using a one way cylinder. Jim
 
Finally getting back to the 400. Hooked up 2 gauges to the hyd lines that go to the 3pt ram. Started & idle the engine, ran the spool. Saw close to 2500 psi, turned the relief valve on the spool down to 1000 psi. Reved the engine up & adjusted to 1200 psi. Need to get couple more fittings to adjust the pressure going to the steering motor.
 
Hey Jim, all is adjusted to IH spec's now that are listed in the service manuals. So far no leaks, fingers crossed. The factory cast tank still has the vent breather installed. Never crossed my mine that need to adjusted, when it comes to hyd's im just dangerous. Fixing High-ways trucks for 20 years doesn't teach one a lot about hydraulic systems too much. Yes they have power steering, mostly when a pump failed on went a new one & away the truck went. Thank you for your help!
 

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