Ford 4500 autodig bucket only?

[FordFortyFiveHundred]

Hi folks, I have a 755 backhoe, a 19-551. I bent the bucket/curl control rod the other day. I pulled the cowl and straightened the rod, but I fear it will happen again. It feels as if there is a dentent on the bucket valve, both to open and close. Is this true? I was joking about the autodig, but it looks like some of them have some sort of simple automation? These feels like there is something wrong with the valve though, as when under heavy load, like pulling the stick in, boom up , and curling the bucket under a big stump, the bucket curl function gets stuck. It continues to curl, and I just bend the control rod trying to get it to stop. I have to relieve pressure on the stick or bucket to get control of the bucket again.

Is this something I can take apart and clean? Or something that has to be brought to a shop? Sorry for the ramble.

 

[mitch504]

There was auto-dig available on the 755 hoe, but it's been a long, long time since I worked on one. I am moving to a different shop, so my old books are all packed up. I can't really remember much about auto-dig, but I am guessing that isn't your problem. I wonder if it could be a worn spool seizing under pressure? (I really want our shrugging smilie back, just imagine me shrugging here.)

 

[FordFortyFiveHundred]

Today it has gotten much worse. I curled the bucket in to lift a root, and it kept going. I bent the control rod trying to get it to release the stump, and tried tapping the end of the spool with a pry bar, no luck. I can pull the control lever towards myself slightly, and see the spool move out. It will not return to neutral, or beyond to the dump position. The hydraulics are now under constant load, unless I use a different hydraulic circuit. Even when I shut down the tractor and remove all load from the hydraulics, I cannot get it to release. I am going to pull the hoe off and remove the valve block, unless someone has a better idea. Is there somewhere I can buy parts for this valve bank, or send it for a rebuild? Or better to just buy a new bucket valve, if the bank can be split apart?

 

[Delmer]

If the spool will move out of the valve but not return, take the bottom cover off the other end of the spool. Usually on the bottom of the valve bank when the spools are vertical. The o ring seal on the spool will leak, fill that cover up with oil, and then you can't get it to go back against the oil pressure. If the cover is full of oil, you have your answer. If there's no oil, then look at the rest of the stuff in there. Don't take the valve bank out unless you have to. Take that spool out if there's nothing obvious in the bottom. Careful when you take that cover off in case something wants to fly out.

 

[FordFortyFiveHundred]

If the spool will move out of the valve but not return, take the bottom cover off the other end of the spool. Usually on the bottom of the valve bank when the spools are vertical. The o ring seal on the spool will leak, fill that cover up with oil, and then you can't get it to go back against the oil pressure. If the cover is full of oil, you have your answer. If there's no oil, then look at the rest of the stuff in there. Don't take the valve bank out unless you have to. Take that spool out if there's nothing obvious in the bottom. Careful when you take that cover off in case something wants to fly out.

Thank you Delmer, this gives me hope. are you referring to the high lighted cover in the attached image? (item 23). I happened to find another valve bank in my state (1.5hrs away) for $175. Supposedly it was re-sealed, can I say no? They are $3000 from Messicks.

 

[Delmer]

yes, and 28 and 29 look like the seal that will leak to fill it with oil. 24 bolt can also back out and keep it from moving all the way if there's no oil.

Don't know what to say on the valve, you'll know more when you get that cover off.

 

[mitch504]

Thanks Delmer.

I knew I was forgetting something I had seen. I hate that feeling, it'll nag me for days.

 

[FordFortyFiveHundred]

Hi folks, I pulled the cap off the tractor side of the valve (cap end). It requires a 12 point 1/4" socket for anyone following in my footsteps....
No hydraulic fluid came out, dry as a bone. I removed the linkage from the smart end of the spool, and I am able to rotate the valve freely CW or CCW. I can also push the valve towards the rear of the of the tractor ~1/8". It is clearly stuck in the curl position, and it feels like there is a hard stop in there, like metal on metal. Questions:
1) How do I remove the spool? I assume I hold the front of the spool, and rotate the flat head on the end CCW?
2) Since I cannot get the spool to move towards the front of the tractor, can it come out the front?

 

[Delmer]

Did you bugger up that screw slot or was it like that? To take the spool out, you should only have to remove that screw and everything on that end of the spool, it SHOULD come out either? end at that point, no rotation needed. 27 28 29 have to come off too.

If it's stuck, that's the reason for your problem, either cracked/warped valve body, or foreign matter in the way. You could try taking the affected hoses off of that spool and fishing around with a little magnet or grabber. or just a piece of copper wire to try to dislodge the bit.

That other valve bank looks a lot better now than it did at my last post. I'd still figure out what's wrong first.

 

[FordFortyFiveHundred]

No, I noted that too. Someone has been in here before me. I'll try to get the screw out and pull out the valve from the front. Thanks for the ideas.

 

[FordFortyFiveHundred]

OK, i was able to drive the spool out from the rear of the tractor towards the front. There are no visible scars or wear anywhere on the spool. It is straight as far as I can tell, rolling on a relatively flat surface. When reinstalling, there is a definite point where the spool catches on something. Are there o-rings inside the valve body? They are not shown on the exploded diagram, but that is how it feels.

When installing the spool, it is very smooth for the first ~2-3". Then it is as if there is a very tight fitting 0-ring in the inside bore of the valve body, and I can hit the spool against it. With a light tap I can get past the obstruction, with only a little increase in the spools' resistance to motion. Another inch of travel reached another obstruction, same story, then a third. At this point the spool is fully inserted, and very hard to move. I can pull the spool to the rear of the tractor using the level linkage, but the spool does not return to the neutral position by itself, and the control rod bends when I try to put it back into the neutral position. I have to use a long screw driver and tap the spool out the tractor end of the valve body.

I have also removed the cover, seal and o-ring from the hoe end of the valve body, with now change. I have cranked the engine over to try to flush any obstructions from the inside of the spool bore. I have shined a light from both ends, and cannot see any damage, or o-rings that might provide the restriction I feel.

I am quite stumped, I welcome suggestions.

 

[FordFortyFiveHundred]

Can I swap say the swing spool with the bucket spool? See if the issue follows the spool or the bore?

 

[Delmer]

There's no internal orings that I know of in valves, it's all metal to metal tight fitting. You could have a cracked valve body, no other explanation I can think of. The obstructions you're hitting are the different passages, extend, retract, center, and the spool is bending a little to fit through them because they're no longer in line. My best guess.

Get that other valve bank.

Unless there's something major that just got bent with the mounting of that valve body, or forcing it to twist? I suppose you could have had something jammed in between the spool and one passage and now you have a burr on one spot. You could try rotating the spool, even using some valve grinding compound (not for this kind of valve! off label use at your own risk), but you might as well get the other valve by the time you take it out and apart.

The spools are matched to the bore individually as far as I know, but what do you have to lose swapping the bucket and swing spools?