Thomas Backhoe

[Jyuma]

I dragged my Thomas backhoe (BH-108) out of the underbrush that had claimed it many years ago and set it down in the shop. Of course it's a mess.

In the photo below showing a closeup of the linkages, the stabilizer hydro linkages (between the two bucket control linkages) move okay but all the bucket control linkages are frozen in place... looks like rust got the better of them...

In the photo above (Boot removed so you can see the linkages)... do you see the 3 rusted 11mm bolt heads that hold down the plate to the body of the valve assembly? If I remove those 3 bolts to remove the plate, will the hydro valve insides come with it? I don't have a service manual for the BH and I'd hate to have the guts come apart and not know how to put it all back together. If I had an exploded view I'd at least have a fighting chance.
Any ideas?
Thanks

 

[Tazza]

The rusted bits i think are the spools. You will need to try and pull them up high enough to get the rust off so they can slide back down through the valve body. If you force it, you will potentially cause more damage. From the rust on the spools, you may have a hard time getting them to not leak when its all free....
I don't know what is under the plate, but nothing should leap out at you when its off though. Think of it as an adventure

 

[Jyuma]

The rusted bits i think are the spools. You will need to try and pull them up high enough to get the rust off so they can slide back down through the valve body. If you force it, you will potentially cause more damage. From the rust on the spools, you may have a hard time getting them to not leak when its all free....
I don't know what is under the plate, but nothing should leap out at you when its off though. Think of it as an adventure

Let Ed's excellent adventure begin.

bTw... I worked the loader hard yesterday for the first time in years... digging with the toothed bucket in virgin hard-pack. Nothing broke... no leaks... and the blow-by even got better. The basic no-frills Thomas really is a tank on wheels.
One question though... the hydraulics under heavy load cause the machine noise to go through the roof. The hydrostatic drive motors appear to be the culprit. As soon as you put the machine in motion (especially carrying a load) the drive motors scream and the entire machine begins a high pitched rattle. It's like working inside a blender filled with marbles. Any idea what might cause the drive motors to make that much noise? I don't think it's the pump because if I'm not moving the noise is gone. I can lift a bucket filled with dirt and although you can notice the increased drag on the engine, there is no loud vibration like when the machine is moving. The noise is especially ear piercing when turning.
I realize that it's not much to go on... but any ideas where to look? I'm sure the machine wasn't designed to make that much noise.
Ed

 

[Tazza]

Let Ed's excellent adventure begin.
bTw... I worked the loader hard yesterday for the first time in years... digging with the toothed bucket in virgin hard-pack. Nothing broke... no leaks... and the blow-by even got better. The basic no-frills Thomas really is a tank on wheels.
One question though... the hydraulics under heavy load cause the machine noise to go through the roof. The hydrostatic drive motors appear to be the culprit. As soon as you put the machine in motion (especially carrying a load) the drive motors scream and the entire machine begins a high pitched rattle. It's like working inside a blender filled with marbles. Any idea what might cause the drive motors to make that much noise? I don't think it's the pump because if I'm not moving the noise is gone. I can lift a bucket filled with dirt and although you can notice the increased drag on the engine, there is no loud vibration like when the machine is moving. The noise is especially ear piercing when turning.
I realize that it's not much to go on... but any ideas where to look? I'm sure the machine wasn't designed to make that much noise.
Ed

Hydrostatics are always noisy to a degree, the pump and motors are probably both to blame for the noise. Is your oil foamy at all? airation can make the noise a lot worse. Does the pump get hot fast?
Some are just always noisy, not a lot you can do.
Good to hear its going strong!

 

[Jyuma]

Hydrostatics are always noisy to a degree, the pump and motors are probably both to blame for the noise. Is your oil foamy at all? airation can make the noise a lot worse. Does the pump get hot fast?
Some are just always noisy, not a lot you can do.
Good to hear its going strong!

Oil is not foamy and the pump doesn't get hot fast (although it does heat up).
I'm thinking that maybe the cage and just about everything else not welded together is loose due to age and whatever vibration is being generating by the drive motors is shaking the daylights out of all the metal to metal junction points.
I wouldn't have mentioned it if not for the fact that the other day I was on a job site where a Gehl was being used and it hardly make any noise at all. I couldn't believe the difference. I guess I'll just live with it.

 

[Tazza]

Oil is not foamy and the pump doesn't get hot fast (although it does heat up).
I'm thinking that maybe the cage and just about everything else not welded together is loose due to age and whatever vibration is being generating by the drive motors is shaking the daylights out of all the metal to metal junction points.
I wouldn't have mentioned it if not for the fact that the other day I was on a job site where a Gehl was being used and it hardly make any noise at all. I couldn't believe the difference. I guess I'll just live with it.

Some purr like a kitten, others... not so much.
Does adjusting the engine revs make a difference? if the motor is running too slow, the hydros can be louder than when running flat out. Just something to try.

 

[Jyuma]

Some purr like a kitten, others... not so much.
Does adjusting the engine revs make a difference? if the motor is running too slow, the hydros can be louder than when running flat out. Just something to try.

Tazza
I run the machine at between 1/2 and 2/3rds power.
bTw... I finished cleaning up the backhoe controls. They were a real mess.
Here are some progress photos...

Rust is everywhere.
Picture below... can you imagine, those two rusty shafts have to be able to move up and down? No chance right?

Believe it or not they cleaned up real nice and now the controls work fine.
Below is a picture after everything was cleaned, greased and put back together.

 

[Tazza]

Tazza
I run the machine at between 1/2 and 2/3rds power.
bTw... I finished cleaning up the backhoe controls. They were a real mess.
Here are some progress photos...

Rust is everywhere.
Picture below... can you imagine, those two rusty shafts have to be able to move up and down? No chance right?


Believe it or not they cleaned up real nice and now the controls work fine.
Below is a picture after everything was cleaned, greased and put back together.

They do look pretty nasty. Hopefully the scoring on the spools isn't too bad to cause it to leak, but it is possible it will later on.
Now all you have to do is go find things to dig up

 

[skidsteer.ca]

They do look pretty nasty. Hopefully the scoring on the spools isn't too bad to cause it to leak, but it is possible it will later on.
Now all you have to do is go find things to dig up

If the spools are rough they will wear your new seals away faster is all. Hopefully they are good.
Skidsteer.ca

 

[Jyuma]

If the spools are rough they will wear your new seals away faster is all. Hopefully they are good.
Skidsteer.ca

Thanks for all the help. Now for my next dumb question...
I finally located a hydro shop near my home and sure enough they can make any hose or match just about any seal you need. I had 2 new supply hoses made for the backhoe... the two hoses that connect to the PTO quick disconnects. I want to pump hydro through the backhoe lines and cylinders and then into a bucket for disposal. Which line do I put in the bucket? Is there a supply and return and if so how do I know which is which?
Pictures...

Can I tell by which quick disconnect is the male versus the female? In the photo above the quick disconnect attached on the machine side (on the right looking at the photo) is the male disconnect but when I engaged the PTO it's the other hose that blew apart.
Maybe I'm being dense and it doesn't matter which hose I put in the bucket but I really want to get the hydro out of all the lines and cylinders in the backhoe. When I disconnected the lines at the backhoe, clear water ran out followed by brown mud, so I should flush the entire system.

 

[Jyuma]

Thanks for all the help. Now for my next dumb question...
I finally located a hydro shop near my home and sure enough they can make any hose or match just about any seal you need. I had 2 new supply hoses made for the backhoe... the two hoses that connect to the PTO quick disconnects. I want to pump hydro through the backhoe lines and cylinders and then into a bucket for disposal. Which line do I put in the bucket? Is there a supply and return and if so how do I know which is which?
Pictures...



Can I tell by which quick disconnect is the male versus the female? In the photo above the quick disconnect attached on the machine side (on the right looking at the photo) is the male disconnect but when I engaged the PTO it's the other hose that blew apart.
Maybe I'm being dense and it doesn't matter which hose I put in the bucket but I really want to get the hydro out of all the lines and cylinders in the backhoe. When I disconnected the lines at the backhoe, clear water ran out followed by brown mud, so I should flush the entire system.

Please ignore my last post.
I just checked in the service manual and believe it or not, even after owning this loader for 20 years I never realized that the PTO foot pedal works in both directions just like the boom and bucket foot pedals. My only defense is that I only own the one attachment (backhoe) and I never did anything but push down with my toe on the PTO pedal.
I never even considered that you could also push down with the heal and activate the PTO in the opposite direction. Duh. It all seems so logical to me now but I just never needed to use the PTO that way.
According to the service manual, pushing the PTO lever down with the toe (spool in) applies power to the female quick disconnect, and applying pressure down with the heal (spool out) applies power to the male quick disconnect. Problem solved.
Thanks... and sorry for being so dumb.
Ed

 

[Tazza]

Please ignore my last post.
I just checked in the service manual and believe it or not, even after owning this loader for 20 years I never realized that the PTO foot pedal works in both directions just like the boom and bucket foot pedals. My only defense is that I only own the one attachment (backhoe) and I never did anything but push down with my toe on the PTO pedal.
I never even considered that you could also push down with the heal and activate the PTO in the opposite direction. Duh. It all seems so logical to me now but I just never needed to use the PTO that way.
According to the service manual, pushing the PTO lever down with the toe (spool in) applies power to the female quick disconnect, and applying pressure down with the heal (spool out) applies power to the male quick disconnect. Problem solved.
Thanks... and sorry for being so dumb.
Ed

Not at all dumb. Usually in one direction the pedal can be locked to provide non stop flow to the attachment, the other direction will not lock.
Good luck purging the system. Remember when its running, oil will be flowing past the control block and back to the machine. Only when you operate a function will you get oil to move to/from a cylinder to purge it like i assume you want to do. The best way is to remove the hoses from the rams and stroke it all the way in and out by hand to get all the oil out that you can.

 

[Jyuma]

Not at all dumb. Usually in one direction the pedal can be locked to provide non stop flow to the attachment, the other direction will not lock.
Good luck purging the system. Remember when its running, oil will be flowing past the control block and back to the machine. Only when you operate a function will you get oil to move to/from a cylinder to purge it like i assume you want to do. The best way is to remove the hoses from the rams and stroke it all the way in and out by hand to get all the oil out that you can.

You were right Tazza... the PTO foot pedal locks in the toe position but not the heal position.
I disconnected the backhoe hose at the male quick disconnect and removed the connector from the hose so it was open. I placed the open end of the hose in a 6 gallon container and engaged the PTO (obviously with the engine running). As fast as I could get out of the loader to check the flow rate thru the open hose, it had pumped out about 2 gallons of what looked like reasonably good 10W30 motor oil and then just sputtered. Apparently all I had in my 8 gallon reservoir was 2 gallons.

I put 5 quarts of new oil in the reservoir and started the engine again. It immediately pumped out 5 quarts of what looked like milky white oily water. I put in another 5 quarts and repeated the process. Again all 5 quarts pumped out almost immediately this time a little less milky white but still not what you you want flowing thru your hydraulics. I put in another 5 quarts and repeated the process again with pretty much the same result... out came 5 quarts of milky white oil that is just unacceptable as hydro fluid.
That's when I stopped. I've now cycled almost 4 gallons of fresh hydro thru the system and I'm still getting milky white oil out. Am I doing something wrong or do I just need to sacrifice as much fresh hydro as it takes to get clean oil thru the system?

 

[Tazza]

You were right Tazza... the PTO foot pedal locks in the toe position but not the heal position.
I disconnected the backhoe hose at the male quick disconnect and removed the connector from the hose so it was open. I placed the open end of the hose in a 6 gallon container and engaged the PTO (obviously with the engine running). As fast as I could get out of the loader to check the flow rate thru the open hose, it had pumped out about 2 gallons of what looked like reasonably good 10W30 motor oil and then just sputtered. Apparently all I had in my 8 gallon reservoir was 2 gallons.
I put 5 quarts of new oil in the reservoir and started the engine again. It immediately pumped out 5 quarts of what looked like milky white oily water. I put in another 5 quarts and repeated the process. Again all 5 quarts pumped out almost immediately this time a little less milky white but still not what you you want flowing thru your hydraulics. I put in another 5 quarts and repeated the process again with pretty much the same result... out came 5 quarts of milky white oil that is just unacceptable as hydro fluid.
That's when I stopped. I've now cycled almost 4 gallons of fresh hydro thru the system and I'm still getting milky white oil out. Am I doing something wrong or do I just need to sacrifice as much fresh hydro as it takes to get clean oil thru the system?

As i mentioned earlier, you should crack the cylinder hoses and stroke the cylinders, this will get all you can out. Thats the problem with closed systems like this. The oil only moves when the cylinder is moving, but to move it you will get that crud into your machine....
When you aren't operating a cylinder on the hoe, oil flows through the control block then back to your machine without entering any of the cylinders, basically this oil that does this and into the bucket is wasted, when you operate a cylinder, the fresh oil will mix with the old then back to the bucket.
When you have milky oil in your system, the only way is to run the machine, drain it then run it again with fresh oil. It takes a bit to get it out, but it will get there with a few cycles. I have done this before. Run the machine, lift tilt and drive, drain the oil with the aux couplers at idle. Shut off when it splutters, re-fill and repeat. Even if you only put a few litres in, get it moving around.
Good luck with it, you don't want any of that milky stuff in the system!

 

[Jyuma]

As i mentioned earlier, you should crack the cylinder hoses and stroke the cylinders, this will get all you can out. Thats the problem with closed systems like this. The oil only moves when the cylinder is moving, but to move it you will get that crud into your machine....
When you aren't operating a cylinder on the hoe, oil flows through the control block then back to your machine without entering any of the cylinders, basically this oil that does this and into the bucket is wasted, when you operate a cylinder, the fresh oil will mix with the old then back to the bucket.
When you have milky oil in your system, the only way is to run the machine, drain it then run it again with fresh oil. It takes a bit to get it out, but it will get there with a few cycles. I have done this before. Run the machine, lift tilt and drive, drain the oil with the aux couplers at idle. Shut off when it splutters, re-fill and repeat. Even if you only put a few litres in, get it moving around.
Good luck with it, you don't want any of that milky stuff in the system!

Finished the purge (it too a few more times) and the oil looked good, so I changed the filter, filled the hydro and operated the backhoe controls. The good news is they all worked. The bad news is that the hydro leaks from all over the backhoe.
I shut it down and put it back in the shop. Tomorrow I'll begin a tear-down and rebuild of all the hydraulics in the backhoe. Years ago I bought every “O” ring and every seal for the backhoe control block but I never did the job so I still have all the kits.
Pictures will be coming.

 

[Jyuma]

Finished the purge (it too a few more times) and the oil looked good, so I changed the filter, filled the hydro and operated the backhoe controls. The good news is they all worked. The bad news is that the hydro leaks from all over the backhoe.
I shut it down and put it back in the shop. Tomorrow I'll begin a tear-down and rebuild of all the hydraulics in the backhoe. Years ago I bought every “O” ring and every seal for the backhoe control block but I never did the job so I still have all the kits.
Pictures will be coming.

Got the control block/manifold out and sitting on the bench. I have no idea where to start.

I guess I'll just start taking things apart.
bTw... man this thing is heavy!!!

 

[Jyuma]

Got the control block/manifold out and sitting on the bench. I have no idea where to start.
I guess I'll just start taking things apart.
bTw... man this thing is heavy!!!

I've searched the Internet for hours trying to find information on this control valve setup but all I could come up with is that it is a Kontak control valve and something similar (another Kontak) is used in a Case D100XR backhoe.
bTw... if the Case site is to be believed, this valve assembly costs over $1100.00 bucks USD. Holy crap... no wonder it's so heavy... it's made of gold.

Based on what I saw on the case site, it looks like I need to take those little caps off from the bottom of each valve (Phillip's head screws... Grrr!) and then there should be a retaining screw inside that secures the shaft (spool) via a spring return and a whole mess of “O” rings and the like. Then the entire spool should lift out from the top.
I checked in the rebuild kits I bought 10 years ago (rofl) and sure enough I have 6 of everything and then two packages of various rings and seals which I assume are used in the end-caps that hold this whole mess together.
More pictures as soon as I get this thing apart.

 

[Tazza]

I've searched the Internet for hours trying to find information on this control valve setup but all I could come up with is that it is a Kontak control valve and something similar (another Kontak) is used in a Case D100XR backhoe.
bTw... if the Case site is to be believed, this valve assembly costs over $1100.00 bucks USD. Holy crap... no wonder it's so heavy... it's made of gold.
Based on what I saw on the case site, it looks like I need to take those little caps off from the bottom of each valve (Phillip's head screws... Grrr!) and then there should be a retaining screw inside that secures the shaft (spool) via a spring return and a whole mess of “O” rings and the like. Then the entire spool should lift out from the top.
I checked in the rebuild kits I bought 10 years ago (rofl) and sure enough I have 6 of everything and then two packages of various rings and seals which I assume are used in the end-caps that hold this whole mess together.
More pictures as soon as I get this thing apart.

The bottom caps should have springs to return the spools to centre. Hopefully you can draw them down instead of removing the spring and pulling it up. Some times the bolts holding the springs are held in with loctite, and you need to heat them to get it to release, so if you can avoid that, its for the best.
Good to hear it up and running, well was. Getting the old oil out can be a pain, i had to do a V twin engine on the weekend, took 6 changes to get it to look like it should.

 

[Jyuma]

The bottom caps should have springs to return the spools to centre. Hopefully you can draw them down instead of removing the spring and pulling it up. Some times the bolts holding the springs are held in with loctite, and you need to heat them to get it to release, so if you can avoid that, its for the best.
Good to hear it up and running, well was. Getting the old oil out can be a pain, i had to do a V twin engine on the weekend, took 6 changes to get it to look like it should.

Am I seeing what I think I'm seeing? Are there like 6 “O” rings inside the machined hydro valve?
I removed the first spool. Here is a picture...

It looks like at least 4 “O” rings would be required... one to the right of the spring in the picture and one to the left of the flat with the hole in it. And one for each of the two lands with the machined grooves. But when I look inside the hole bored in the block that the spool came out of (pictured below) it looks like there are six “O” rings but it is very difficult to see inside the bored hole to be sure.

Is it your experience that there are as many as 6 “O” rings for each spool? I suppose I could try a long angled pick and see if I can remove the “O” rings but how would I get the new ones all the way to where they go inside that long narrow hole? Is there a special trick to it? Like maybe fold the “O” ring over on itself and just work it to the grove inside the hole and then let the “O” ring seek it's original shape inside the groove? I never had to put “O” rings that far down a bore before.