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Discussion Starter · #1 ·
I bought an original dual SCV set up to mount onto my 1020. Looking everything over they look alright with the exception of the QDs which are plugged up with mud, but the valve levers are extremely hard to move. One of them I can't move at all, and the other is extremely stiff. I haven't mounted it up yet to see if anything works. The stiff levers have me worried that I might need to open them up and do a rebuild on them. The tractor they came off of had a stuck motor, so i've no idea how long these have been sitting. How hard is it to rebuild the valves?

Or, would it be better to mount them up to the tractor so they fill up with oil and cycle them a few times and see if/how they operate? Thinking this might be a better route. Mount them, hook up the supply and route the return to a bucket. Im not crazy about routing the returns straight to the tractor and possibly introduce some contaminants to my newly cleaned out transmission. Thoughts?
 

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There aren't many replaceable parts, but if you can get the spools out they can be carefully polished. Can you post a picture of it?
 

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There aren't many replaceable parts, but if you can get the spools out they can be carefully polished. Can you post a picture of it?
Kenny
I know you were thinking ""spool not poppet valves scv"" & I'm not attempting to seem like a smart Alec!! JD utility factory scv's each have 4 poppet valves with rockers that can be difficult to adjust correct clearances especially for the1st time rebuilder & sometimes even subsequent times to rebuild/adjust. IMHO JD engineers went out of there way to make these type & other control valves too complicated. There are 4 set screws that require adjustment after valve reassembly & back when I served as a JD dealer service manager I had several mechanics that didn't get this adjustment correct after several attempts.
 

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Gumbi
My suggestion before resorting to disassembly would be to remove covers(key 5) in above photo & spray a good penetrating oil such as PB-blaster or Kroil on the operating parts while moving control levers especially spraying the shafts that go through the rockers(key 19).
 

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Gumbi
My suggestion before resorting to disassembly would be to remove covers(key 5) in above photo & spray a good penetrating oil such as PB-blaster or Kroil on the operating parts while moving control levers especially spraying the shafts that go through the rockers(key 19).
Exactly what I was going to suggest. Free them up before putting on your tractor.
If you "split" them, use new O-rings between the two valves. The pair on my 2030 started to leak, it was these O-rings that failed.
I use one for my grapple, I love the detent for both open and close of the grapple cylinders.
If you have the ported transmission filter cover, I would recommend the "return to filter" kit.
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Zebfafive
I think scv oil returning to ported filter cover is important in high gpm usage such as operating a orbit motor but for normal 8'' stroke cylinder operation is a waste of $$$$. Hose on ported filter cover will make it more difficult to change hyd filter & get seal correctly in place.
 

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Mine came with the return to filter cover kit. Maybe it once had a loader connected to the rear SCVs? When I bought, they said they had a JD 175 loader for it, if I wanted to add it.
It made adding my 245 loader with mid valve easy. All I had to buy were two tees, one for pressure and one for return.
 

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In the area between the two valve bodies is a small pocket that is prone to dirt and moisture to collect and cause the operating shaft to rust tight. See diagram. Try cleaning out that little pocket with a small pick and compressed air. Then soak that pocket with penetrating oil to help free up the shafts. Unfortunately, many times I have seen the shaft rusted so badly that you end up with an oil leak in that area due to shaft pitting around oring sealing area. If leak occurs after freeing up and operating, the shaft can be replaced without entire disassembly of all the valves if everything else works properly.
 

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Discussion Starter · #12 ·
I finally got around to installing this dual scv setup along with a later style power steering column to my tractor. This is a bit of a mismatch of parts (my tractor is an early model '66, all of these parts come off a later model), but so far everything is working as it should. BTW the p-steering is the cat's meow.....so fast, so smooth, so much better than armstrong steering.

I have the SCV's mounted and plumbed up and went to test for leaks with the tractor running. To test the scv's I connected a hose to the QD's for each SCV and looped it back on itself and operated the levers. First off, I noticed that once the valves had oil in them, the levers freed themselves up and move fairly smoothly through their respective ranges.
Second thing I immediately noticed is that the neither the rockshaft or the power steering work. Both of these worked fine before I had hooked up the supply line to he scv's. I had tested their function after the p-steering install by capping off the scv supply. This tells me that one or both of the scv's has a major leak internally and bypassing all flow to the sump. I have an idea which one is leaking as you can feel oil flowing in the hose I have hooked up to the QD loop for the outer scv when the lever is in the neutral position.

To me this means that I need the scv rebuilt because it has a major leak internally, and if i have one rebuilt, i'd rather just do both. Is it possible for one to do this themselves, or is there a member on here that rebuilds them and has the correct tools? I know TxJim has mentioned that they are a bit finnicky to get adjusted properly.

Lastly, I know it will be asked; Yes I have a PCV installed, but it has been gutted of the actual valve. Being as the tractor is a '66, there is no hole drilled into the transmission where the low pressure bleed hole is located on the PCV. So, i removed the valve internals and mounted it up so that the later style hyd lines will mount up like they would on any other older model. In this set up, the pcv is just acting like a T in the lines. Yes i know this means that if there is leak in the rockshaft or the scvs, i will lose steering - hence my diagnosis above. The entire rockshaft was rebuilt two years ago and works properly along with the rest of the hyd system.
 

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I suggest to insert a male hyd tip with a hyd gauge installed then record pressures of each of the 4 breakaway coupler with control lever in both pressure & neutral positions. This should allow you to single out which valve body is leaking internally.
Yes the rockers are touchy to adjust. Back when I served as a JD dealer service manager I had several different employees under my supervision that had "great difficulty adjusting" those valve rocker clearances. I've read where adjusting is easier using compressed air in lieu of a dial micrometer but I've never witnessed this type adjustment in person.

IMHO rather than install a PCV with spool removed & oil galley blocked off I would have just utilized a "TEE fitting" to attach line to supply pressure oil to scv.
 

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Discussion Starter · #14 ·
TxJim, I hadn't thought of hooking up a pressure guage to the couplers for singling out the leak. I will look into doing that this weekend hopefully. As far as rebuilding the scv, Is it just the adjustment procedures that are difficult, or are there other task with the internals that a decent shade tree mechanic would have trouble with? Are there special tools needed? I remember reading back in the manual that there was a plate of some sort that needed to be bolted on top the valve when adjusting the rockers but that was it.

As for using the pcv.......I initially did install a TEE, but for some reason the rear hydraulic line AT23550 came out to be right at a 1/2" too short to reach the TEE. The PCV would mount and hook up to the hydraulic line with no issues. To use a TEE I believe I would have needed one of the other options for the rear oil line, but neither of them have the stub out to hook up the supply pressure line for a closed center p-steering column. I was REALLY thinking about drilling out the low pressure bleed hole for the pcv, but I'm a bit nervous about putting a hole in the main transmission casting.
 

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Discussion Starter · #16 ·
Got around to pressure testing the QD's this past week. Out of the 4 QD outlets, only one of them would register the correct pressure 2200 psi. The other 3 did not show anything on the gauge. I opened up the Transmission fill cap and took a look inside while the tractor was running and there is oil continuously being sprayed out from the SCV return port with the levers in neutral. So does this mean that the poppets are stuck open in the SCV's? I'm not sure on what other testing I can do.

I'm about 99% sure now that the valves will need to be rebuilt. I decided to take them off the tractor for now so that I can still use it for other task. I'm thinking that I may attempt at rebuilding them myself depending on the cost.
 

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Got around to pressure testing the QD's this past week. Out of the 4 QD outlets, only one of them would register the correct pressure 2200 psi. The other 3 did not show anything on the gauge. I opened up the Transmission fill cap and took a look inside while the tractor was running and there is oil continuously being sprayed out from the SCV return port with the levers in neutral. So does this mean that the poppets are stuck open in the SCV's? I'm not sure on what other testing I can do.

I'm about 99% sure now that the valves will need to be rebuilt. I decided to take them off the tractor for now so that I can still use it for other task. I'm thinking that I may attempt at rebuilding them myself depending on the cost.
I think you will find a stuck poppet, something (dirt) keeping a valve from seating, or a worn valve/seat. You should not have return to sump when the valve is not in use.
 
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Discussion Starter · #20 ·
Or insufficient clearance between rocker & roller on poppet valves.
Yeah either way, the only way to fix it is to tear down both valves and do a full rebuild. I've found a couple of guys that will rebuild these through forums and facebook. I think i'll try and do them myself though. My biggest concern is that I can't re-grind the valve seats without the special set of stones that are mentioned in the tech manual. So if the seats need to be re-ground, I won't be able to fix them at all myself and will still need to send them out for a rebuild. We'll see
 
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