Replacing the Deere 425 steering valve assembly hydraulic lines tutorial

   / Replacing the Deere 425 steering valve assembly hydraulic lines tutorial #1  

Baymee

New member
Joined
Dec 3, 2022
Messages
2
Tractor
1988 316
I reluctantly took on the job of replacing the O rings and hydraulic lines on a Deere 425. I wasn't able to find any pictorial or explanation of how to do it on any of the forums or net. So, I am hoping someone will benefit from this tutorial. It's not an overly hard job to do and no exotic tools are needed, but there are many steps involved and if not done correctly, you'll have to do it all over again. Get your tools under the tractor before you begin, as well as a container to collect leaking oil and a bunch of rags. You may not use every tool. It was my first time doing this and the job took 6 hours and about $400 in parts.

Have the following tools close by:

Air nozzle to blow off all dirt around the fittings
Carb cleaner and a stiff brush to clean with
Some sort of sharp pick/awl to remove the O rings on the steel lines or male adaptors
Oil dispenser

Paint marker to mark the hoses
Open end wrenches: 1/2, 9/16, 5/8, 11/16, 3/4, 13/16, and 7/8
3/4 x 13/16 and 1/2 x 9/16 thin jam nut wrenches
2" OR 3" x 3/8 drive extensions and ratchet

A 1" flex extension.
6" extension drive X 3/8" drive
3/4" deep socket to remove the tie rod linkage, if necessary
A pipe to fit over the end of the wrenches for leverage, if necessary

9/16" shallow socket
1/2" deep socket
A Gearwrench adaptor: 3/8" to insert into the 1/2" deepwell socket and 9/16" on the other end
1/2" crows foot
1 inch x 3/8" extension

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To begin the project, I used my overhead crane to lift the tractor up and then used cable and chain for safety devices. I was able to sit under there and work easily. If your only option is to work from below on blocks, expect to get soaked with hydraulic fluid and grime. There is very little loss of oil when the steering valve assembly lines are removed, but the lines themselves will empty of their fluid.

I have listed below which lines go into the respective ports of the steering valve assembly and where the other end of the lines connect to.


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Remove the female swivel fitting at the tee, shown to the left of #6, second picture up. Next, at the valve assembly on the outside of the frame, loosen and remove the swivel fitting below #3. I had to remove the lines #1 and #2 to access #3. These steps require a 3/4" open end wrench and 13/16" thin jam nut open-end wrench and possibly a pipe wrench.

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If any of the male fittings are removed or become loosened during the loosening of the swivel nut, the O ring(s) must be replaced to ensure a leak-free repair. There are two O rings on this fitting shown two pictures above. The O ring seen on the male adaptor fitting is part # R26448. The O ring in the center of the other side of the male adaptor in the second picture is part # T77613

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Alternately, the bolt can be removed with a flex extension and 1/2" deep socket.

The five lines that plug into the steering valve assembly all use the O ring shown in this picture. The part number is T36492 and you will need 5. I would buy an extra or two in case you damage one while trying to install it. Always insert into the ports, well lubricated.

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Next, I removed the female swivel nut of the large 3/8" line at the transmission, which can be done from underneath. There will be an O ring (part # T77613) to replace on the male adaptor where the hose connected to. Again, if the male fitting becomes loosened during the loosening of the swivel nut, the O ring(s) must be replaced to ensure a leak-free repair. (See above) This also applies to the power steering fittings.

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Then remove the fittings at the power steering cylinder. I wasn't able to unscrew the male fitting, inboard side, so I had to cut the line and use a socket on the hex fitting and this required removing the tie rod end of the right wheel, using a 7/8" open end wrench and a 3/4" deep socket.

The power steering outboard side at the wheel uses a 45 degree fitting. There is an O ring on each side of that fitting that must be replaced. The O ring part # for the male end that screws into the cylinder is R28728. The O ring that goes in the center of the opposite end of the 45 is Part # T77814.

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REASSEMBLY

Be sure there is no dirt in the open ports.

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All swivel fittings on the steel lines use a NEW O ring (part # T77613) in the center of the male side of the joint. See two pictures above, item #1. Install the lubricated O ring (T77613) into the male side of the T #6, (steering valve assembly underneath) where steel line #4 female swivel will be connected. Install the same O ring into the male fitting on the valve body side of the frame where the female swivels 1,2 and 3 will attach.

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Port #1 is flex hose AM119164, which goes to the outboard side of the front power steering cylinder, closest to the right tire.
Port #2 is flex hose AM106911, which goes to the inboard side of the front power steering cylinder.
Port #3 is the pipe that goes through the frame to the valve body.
Port #4 is the pipe that connects to the tee to the left of #6
Port #5 is flex hose AM115774, which goes back to the fitting above the transmission oil filter.

See picture below, item #1

Install lubricated O ring (part # T36492) on to the end of the steel tube that is inserted into port #4. Insert steel line #4 into its port and seat it. The new O rings make inserting the lines into the ports a bit harder. I inserted the end far enough to get the O ring into the port and then lightly tapped on the fitting with a hammer and punch to fully seat it. The clamp plate will finish the seating when it is bolted down.

Put the clamp plate in place and with each of the remaining four lines, you will need to slightly raise the plate to insert the lines into their ports.

Install the lubricated O ring (T36492) on to the end of flex line (AM119164) and insert it into port #1 and seat it.

Install the lubricated O ring (T36492) on to the end of flex line (AM115774) and insert it into port #5 and seat it.

Install the lubricated O ring (T36492) on to the end of flex line (AM106911) and insert it into port #2 and seat it.

Install the lubricated O ring (T36492) on to the end of steel line #3 and insert it into port #3 and seat it.

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Install the two bolts into the clamp plate and turn them in by hand so that they make light contact with the clamp plate. Then attach the two female swivel fittings of steel lines #3 and #4 and tighten slightly.

Tightening the clamp bolts required different tools, so as not to round off the bolt head. The right bolt was tightened with a crows foot. The left side bolt used these tools, shown below.

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Tighten the clamp plate bolts and torque to about 15 foot pounds. Then fully tighten the two female swivel joint fittings of steel lines #3 and #4.
 
   / Replacing the Deere 425 steering valve assembly hydraulic lines tutorial #2  
Baymee - WELCOME TO TBN 📣

To avoid striping off the corners of the hex nuts on the lines, you should really be using a Flare Nut wrench.
Flare Nut Wrench Set.JPG

Also when working with fluids, you should be wearing some sort of protective, oil proof gloves and safety glasses.

Nice write up.

Richard
 
   / Replacing the Deere 425 steering valve assembly hydraulic lines tutorial #3  
Also welcome to TBN
A bit surprised these are not metric. Hope to not have to follow that procedure, but with your pics it should work out okay.
Appreciate the time and energy to document your repair. The extension tool is a clever idea.

Think if I have to tackle that job, I will first do some serious cleaning of dirt, oil, and grime in hopes the job is easier. Working with hydraulic lines and grime is hard to comfortably look at.
 
   / Replacing the Deere 425 steering valve assembly hydraulic lines tutorial
  • Thread Starter
#4  
Thanks for the observations.

I have a set of flare wrenches and probably every other trick tool in the (Snap-on) book. :). I didn't try the flare wrench, but it's really tight in there and I'm not sure they would fit or be able to turn.
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I ran out of room for more pics, but the crows foot worked well on the right bolt and the flex drive on the left bolt. Everything was SAE; not sure about the threads though. My 316 used some metric.

This wasn't my tractor. The owner asked me a few times over the year about repairing the leaking hose and I kept putting him off because it looked like a daunting job and I had too much other work in the shop.

Unfortunately, if even one hose leaks, this whole procedure has to be done. I want to add about isolating the new hoses against chafing on the frame. They should be insulated better than just being held in those sharp clamps.

The area around the 5 hose ports was surgically clean, although it may not look it.

When I researched this job, I couldn't find anything more than a brief few sentences about doing this, so I took on the challenge of writing up a tutorial about it. Besides being a mechanic, I also wrote service manuals in industry for our equipment. This was at least an 8 hour project and I enjoyed every minute of it.
 
   / Replacing the Deere 425 steering valve assembly hydraulic lines tutorial #5  
This is a great write up that will no doubt be useful to lots of people.
 
 
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