Rebuilding a hydro pump from a D

[Hodge71 664]

Heres the process of tearing down a hydro pump from a D. I will do my best to describe everything in detail so that anyone can handle it. I must say with Paul Frederis help we tore it down, cleaned and rebuilt it in 4 hours including tearing it down a second time because of MAJOR rust issues causing binding of the pistons. I will do this in chronological order as best as I can

Step #1 Here is the pump before tear down. You need to remove the four 12 point bolts using a 3/8 12 point socket wrench in order to seperate the aluminum housing from the cast steel valve body

STEP # 2 shows the bolts out and the pump housings seperated. Be ready to struggle slightly if your pump was never opened. It was necessary for us to put the aluminum part in a vice and hit the steel end with a dead blow hammer and brass punch to get it to sperate from the gasket/adhesive. You must rest the pump on its side or you will lose slippers and other items if you do it in the upright position. Upon opening it a large quantity of rust was found inside formed on the steel end suggesting water infiltration.

Step #3 In this photo you can see the rusty liquid on the slippers and the general shape of them. They were scratched but the corners were square and not rounded over, which is very important

Step #4In this pic Paul is trying to clean the rust off of the oil pump housing. As you can tell it was pretty rough. The 4 bolts here are 12 point also, you need to use a 5/16 12 point socket socket to remove these.

this is another pic of the pump housing and the rust and bolts. Also pay attention to the orientation of the small pin location on the oil pump housing. Its on the botton of the pic and must be that way for reassembly. It is very important for reassembly that this faces the same way.

Step #5 Here is the oil pump gear in the housing. You must mark this on the housing and impeller before you take it apart. Every lobe only fits its mating surface 1 way. If you screw it up the pump will bind and not pump oil to feed the cylinder, slippers and swash plate. The o-rings are the same set up as the manifold with a square backer ring and a regular o-ring on top to seal.

Step #6 In this step you need to remove the charge valves. They are 5/8 standard socket. It is an O.R.B.( O Ring Boss). These were pretty tight but did come loose. Here are some close ups of the charge valve. We made a legal notebook map so we could be sure it all went back together well. one side has a spring and a ball, the other side has a small tapered shaft and spring. Later models of this pump had balls and springs in both sides. One thing to note is that occasionally you will find shims between the spring and ORB fitting. These were installed when the pumps didnt make enough pressure during testing. The shim increased tension on the spring and therefore raises the oil pressure just like it would in an oil pump for an engine.

Step #7Next pics are a close up of the housing showing the accelerator valve removed. There are 2 of these. 1 on each side. They are the large straight head screwdriver tip recessed into the block. They are ORB also but damn were they tight. We needed to use an impact driver to break them loose. All thats inside is a ball and spring.

Step #7Next pic is of the push valve. Remove it and check to be sure there are no gouges in the tapered area. If there are, oil will leak by and cause speed to slow and pump to overheat eventually during use.

Step #8This is the inside of the aluminum housing. It shows the direction control where the swash plate sits. The can be removed if needed by removing the spring clip on the shaft where it comes through the outside of the housing on the flush side, not the long side that the direction linkage attaches. You then pull the shaft out and the swash plate resting surface will clunk into the bottom of the housing for you to pull out. The only reason to do this would be to replace a bad bearing.

Step #9 Here is a close up of the swash plate during polishing. I started with 800 grit, moved to 1200 and then to the crocus cloth as the final step. DO NOT use water to lubricate the crocus cloth. it causes the adhesive to melt and the cloth to become junk. Use oil only for lube. This is a before of the swash plate showing severe rusting from the water that was inside this pump.

this is after the three step polishing sequence. As you can see its a mirror now

Step #10Here is the brass direction control valve plate showing scratches and oxidation. This also goes throught the 3 step process of polishing. This is the same peice after polishing

Step #11 is the polishing of the slippers themselves. We made a diagram so that we could install them back in the bores they came from. After all that work we ended up with my original cylinder too rusty to be used. The slippers bound up and we had to take the pump all apart again and use a different cylinder after we got it all back together and it wouldnt budge.

Step #12 is the installation of the slippers back into the cylinder. Be sure to install the slipper retainer BEFORE you install the slippers. They wont fit if you dont.

Step #13 is the installation of the swash plate back into the direction control section. This pic shows it cleaned

This pic is right before installation of the cylinder and slippers. Use lots of oil on both sides of the swash plate so theres no galling on start up. It will suck to do all this work and wipe it out with a dry start.

Step #13 Assemble with the unit on its side. If you dont, you will lose slippers from the cylinder bore as you slide it down over the shaft and then have to start over. Once the cylinder is installed on the shaft, then flip the housing to the vertical position.

Step #14 is to reinstall the charge valves, accelerator valves, springs and shims where they came from. A little grease on the springs wont hurt. It will stop them from moving and going caddywhompus when you install them in the bore above the ball at the bottom

Step #15 Shows the proper orientation of the oil pump impeller in the housing. Take notice to our marks to be sure we had it right. You then reinstall the pump assembly onto the housing using the four 5/16 12 point cap screws you removed at disassembly. Again be sure the pin is at the bottom when assembling.

Step #16 shows the new gasket prior to assembling both halves . I made this one the same way as the motor housing in my original resto post. Using a hammer to cut the material.

Step #17 its all back together and ready to go back in my 18 Auto.

[AMC RULES 37,130]

This is one awesome how-to Jeff, thanks for sharing. :text-coolphotos:

[racinfool40 202]

Outstanding!!!! I have never messed with a hydro pump yet and have a couple to work on!! No I'm not so worried!!!!!! I vote to moved this to the most useful post area or have it pinned!!! Thanks Hodge71 (Jeff). :handgestures-thumbupright:

[can whlvr 993]

good thread here,does it work though,sure hope so after all the hard work

[dennist 139]

Great thread for sure, as stated above, I have a couple that I dare to take apart now. Thanks

[Hodge71 664]

Thanks for all the poisitive feedback guys. Keep the votes coming and maybe an admin will pin it for us so that it'll be here for all to benefit from. Thats why I did it. Alot of guys were nervous about tearing into one so Paul and I jumped in and now we all can see just how complicated they are. As long as you take your time amd label things its pretty straight forward. I would imagine that a hydro pump from a C is no different. They use a drive pully instead of and engine coupler and its a married system whereas the D uses a divorced system.

[bowtiebutler956 650]

Very informative post. Its amazing how similar the inside of that pump is to a Kubota B8200hst I had to repair a couple of years ago.

Matt :flags-texas:

[wheeledhorseman 574]

:bow-blue: Awesome post Jeff and I'm sure Paul's help was invaluable in what you achieved together.

I've just given it my vote!

They are ORB also but damn were they tight. We needed to use an impact driver to break them loose. All thats inside is a ball and spring.

Was there any visible reason for this or is it just that they did them up that tight at the factory?

The reason I ask is that even with an impact driver I've failed to budge the reverse valve in mine.

Andy

[meadowfield 2,570]

absolutely perfect Jeff !

same principles as rebuilding a multicyliner engine... everything marked and put back in the right place. No need for heavy handiness or gorilla tools

Hope it works well for you now.

mark

[Hodge71 664]

Andy,

There was absolutely no reason for it to be that tight. This pump was definitely never opened up before. All fittings were tightened by an gorilla at the factory. We found no reason for it to be that tight, especially with and o-ring boss fitting. All sealing is done by the o-ring, not the trheads. We tightened all things but I know we didnt do it as tight as they were originally. I guess we shall see if it leaks. I have no doubt it will function perfectly.

Thanks Mark for the compliment.

[pfrederi 17,672]

Awesome post Jeff and I'm sure Paul's help was invaluable in what you achieved together.

I've just given it my vote!

They are ORB also but damn were they tight. We needed to use an impact driver to break them loose. All thats inside is a ball and spring.

Was there any visible reason for this or is it just that they did them up that tight at the factory?

The reason I ask is that even with an impact driver I've failed to budge the reverse valve in mine.

Andy

Andy I do not know why they were so difficult. The day before i had opened up a junker pump (think training aid) and it was a real struggle to get the valves open. Had to soak with PB Blaster and wail away with the impact driver. Chewed up the slot as the bit was as a bit to small. Drag link sockets i had that would fit the slot were to fat to fit into the recess.

It was a real pleasure to work with Jeff on his pump.

Next up is to overhaul mine. I have to get my own 12 point 3/8" and 5/16" sockets.

The pump is actually easier to do than the hydro motor. With the motor you really need a press, and there is a high probability that the spring clip that holds the piston assembly on the shaft will break when you press the shaft out. (at least 2 of the 3 i have tried broke at least one finger on the clip).

Jeff made the pump housing gasket in about 5 minutes...They are also still available from Toro...as are the shims sets for the implement valve. So far I have looked at 2 pumps none had the shims....

A big thanks to Jeff for documenting our day. I had a great time.!!! :greetings-clapyellow:

[Tap53 57]

Just wondering if all the slippers are within .002" of each other and no more than .005" was taken off any particular slipper?

[JamesBe1 82]

Nice work Jeff. I would love to see this in a PDF format that I can download and save it for future reference. Now that I have a clear idea of what to expect inside one of the pumps, I will not be so skiddish about working on mine next time the need arises.

Kinda curious - how did water enter the closed system and cause the rust?

This definitely should be pinned.

[Trouty56 565]

Nice job guys...I still hope I never have to go through the process though.....

[73-18 automatic 8]

Awesome enjoyed reading this

[can whlvr 993]

heres a pic of my broken retainer when i tore this 1975 c160 pump apart,there was other problems so i had to bite the bullet and take it to a shop,so you guys saved some serious cash doing it your self

[Hodge71 664]

James I think water somehow got inside after it was taken off the tractor. There was absoluetly no water in the pump at the time of disassembly. It was perfectly dry inside but you could definitely see a water line where the cylinders below the line were rusted and the cylingders above the line were fine. It was only 3 pistons that would seize in the bores. I believe the cylinder has a machined finish and the pistons are chrome plated because there was absolutely no rust on them at all.

Tap,

All slippers were within spec.

[Tap53 57]

James I think water somehow got inside after it was taken off the tractor. There was absoluetly no water in the pump at the time of disassembly. It was perfectly dry inside but you could definitely see a water line where the cylinders below the line were rusted and the cylingders above the line were fine. It was only 3 pistons that would seize in the bores. I believe the cylinder has a machined finish and the pistons are chrome plated because there was absolutely no rust on them at all.

Tap,

All slippers were within spec.

I figured you checked that, Wasnt trying to be smart, just have seen pumps I've taken apart and slippers were polished on a grinder, 80 grit I think... or else I would ask and get this comment (WHAT!!!)(SLIPPERS???)

Excellent Work

[JamesBe1 82]

Jeff and I were discussing the slippers the other day. I wonder, since they are NLA, and being made of simple brass, how hard could the be to make? If only I had the specs and a lathe. The pistons - well, they are much more difficult, but not impossible to replicate.

Kinda curious, anybody know the specs/dimensions of the slippers?

[pfrederi 17,672]

Jeff and I were discussing the slippers the other day. I wonder, since they are NLA, and being made of simple brass, how hard could the be to make? If only I had the specs and a lathe. The pistons - well, they are much more difficult, but not impossible to replicate.

Kinda curious, anybody know the specs/dimensions of the slippers?

James I am not a machinist but the slippers would seem to be a bit complex. Then there is the issue of how crimp it on to the ball at the end of the piston.

[JamesBe1 82]

Paul. I certainly respect your opinion, you've helped me out immensely here with your knowledge.

I am no machinist either (but I'm a wannabe). I believe that while they may appear complex, they really aren't. The only critical dimension is the inside area that fits around the ball on the piston. The other parts of the slipper would have relatively wider tolerances. No doubt pressing it around the pistons would be a bit tricky, but sometimes the answers are easier than they appear. Also, I hear that brass is one of the easiest materials to machine.

I'm not sure if the slippers and pistons are pressed or crimped. If they are crimped, I think an arbor press with appropriate does would do the trick.

I may be overreaching, but I tend to do that. I learn a lot that way

Either way, I somehow see a lather in my future. Too bad all the good made in America ones are out of my price range I'll probably be stuck with a cheap import knockoff.

Too bad we don't have any current or former Sunstrand employees lurking around here. They would be an invaluable source of knowledge on NLA parts.

James

[pfrederi 17,672]

To add some more info to Jeff’s very useful thread.

Turns out that there is some interchange possible between the hydro motor and hydro pump.

I opened up the hydro pump I hoped to rebuild but the slippers were too far gone. I have collected more motors than pumps and some of the motors had restorable slippers and valve plates. Problem was my first read of the manual focused on the fact the piston block assembly was not interchangeable between motor and pump.

However studying page 43 of the Sundstrand manual lead me to find that there is one-way compatibility. Motor piston blocks can be used on the pump also. (Older version pump piston blocks cannot be used on the motor).

Trying to figure out the difference took some time as one of my motors turned out to have the wrong piston block. (Note that was the motor that came on my D200 and the PO said it had been professionally over hauled. If I ever find the SOB in Connecticut it will not be pretty!)

Bottom line when you look down the splines inside the piston block if they are smooth (only one size/level) it is a pump only block. If you see (or feel) a slight step in the splines (about ½â€ from the bottom) it is a universal piston block. They did the extra machining to make clearance for the snap/clip that is in the motor shaft (but not on the pump shaft.)

You have to change out the 2 retaining washers and coil spring as they are unique to pump or motor. Finding a 15/16 OD washer to make the spring compressor took some time. (turns out 7/16†GR8 washer will work) The spirolock ring is the same in both cases… they come out easily but can be a bit of a pain to reinstall. (same design as the D series PTO)

Anyway I spent a couple hours cleaning and polishing the piston block valve plate and slippers from my old motor (that had a pump piston block in it) and hopefully the rebuilt pump will work well.

One more thing if you are D owner do not over-look pumps from C series. Other than the shaft the innards are interchangeable.

[tommyg 152]

Wow! This post just might cause me to overcome my fear of diving in to my pump on the D180. Thanks for taking the time and all the documentation!

[953 nut 55,090]

:) This is great information, My GT14 Trans is having problems and this has inspired me to give it a try. Thanks!

[pfrederi 17,672]

This is great information, My GT14 Trans is having problems and this has inspired me to give it a try. Thanks!

By all means dive in, but remember GT14s had hydro gear not piston to piston sundstrands. The pump unit will be the same as discussed here. the motor end is completely different and according to WH was non-serviceable.