problems with JD 2440 SCV

[Weston Bend]

I have an early serial number JD 2440 with SCV's that were rebuilt 2 years ago. Unfortunately, about six months later (after warranty ran out on repair) they started leaking. After multiple times having them on and off, changing packings, and gaskets and such. I believe I finally found the leak in the o-ring around the handle. I was told the cases might have a crack so I took them to a local machinist who mag fluxed them and said the housings had no leaks. In doing so, I took out the guts of the SVC (valves, springs, and such). Unfortunately, when I put it back together, I made a mistake with the positioning of the valves. I looked at the manual and it says the high-pressure valves go diagonally of each other. Unfortunately, it doesn't say which position so I watched a youtube video of a someone putting the valves back in to the housing and they did as follows. I realize this is not the exact SVC style for the 2440 but the underside view of the internal workings looks the same as mine so I'm guessing the coupler design difference doesn't affect the internal workings of the SCV.

Now, my only question is the springs. Two of the springs are longer, and two are slightly shorter. On the schematic parts breakout, they have two different numbers, but it's not clear which one goes to the high-pressure valve and which one goes to the low-pressure valves. I put the longer springs on the high-pressure valves. Unfortunately, when I put it all back together, the loader doesn't work, so I know I have something wrong. Any assistance on what I may have done wrong would be appreciated.

Thanks,
Chris

 

[Weston Bend]

One last thought...I'm also questioning if the spring lengths have to do with the position of the handle when installing. I.E. one side of the valves are slightly depressed and the opposite diagonal side is slightly out. Do I just match the spring length to the sides that are depressed? I.E., put the longer spring in the side that has the valve down and put the shorter spring in the side that has the valve slightly further out.

Thanks,

Chris

 

[Tx Jim]

Orientation of valves is immaterial as all 4 valves have same part # & are interchangeable. I only locate 2 larger diameter springs & 1 smaller diameter spring. Adjustment of valve clearances is the important/tricky portion of repairing those SCV's. Without aid of a 2440 tech manual I wouldn't know correct orientation of the 2 larger springs

 

[Weston Bend]

OK, I got this fixed.

Here is my overall set of problems and fixes..
I couldn't stop the leak until I changed the two o-rings on the handles. The other packings were not the problem.

When reassembling the SCV, the cleaner, the better. I had it cleaned with a high-speed wire brush rotary tool.

The orientation of the valves does matter, both from a control standpoint and a fit standpoint.

The high-pressure valves at 1 o'clock and 7 o'clock have to be diagonally oriented. The low-pressure valves are at 11 and 4.
The valves also have to be turned when they go into the cylinders of the SCV case, so they fall down all the way and engage with the cam controller connected to the operation lever. I was inserting the valves but not rotating them, so the U-shaped ends were not aligned with the cams. This is what gave me back the hydraulic function to the loader.

CK

 

[Tx Jim]

OK, I got this fixed.

Here is my overall set of problems and fixes..
I couldn't stop the leak until I changed the two o-rings on the handles. The other packings were not the problem.

When reassembling the SCV, the cleaner, the better. I had it cleaned with a high-speed wire brush rotary tool.

The orientation of the valves does matter, both from a control standpoint and a fit standpoint.

The high-pressure valves at 1 o'clock and 7 o'clock have to be diagonally oriented. The low-pressure valves are at 11 and 4.
The valves also have to be turned when they go into the cylinders of the SCV case, so they fall down all the way and engage with the cam controller connected to the operation lever. I was inserting the valves but not rotating them, so the U-shaped ends were not aligned with the cams. This is what gave me back the hydraulic function to the loader.

CK

All 4 poppet valves are the same IE they have the same part number. Orientation of those valves is immaterial. Adjustment of clearances between rockers & rollers is different for pressure & return valve but valves are identical.

 

[Weston Bend]

2 of the valves have o-rings and backup rings on the top and 2 of the valves don't have the o-rings and backup rings, so I would disagree that they are identical.

 

[Tx Jim]

You can disagree all you desire BUT adding o-rings & backup washers to a part that shares """"SAME IDENTICAL PART NUMBER( AR86535)""""" doesn't mean or indicate the parts are different because they aren't different!! They do serve a different purpose IE pressure & return! . Back in my younger days I spent many hours behind a JD dealership parts counter selling parts to customers.

 

[Jim.ME]

2 of the valves have o-rings and backup rings on the top and 2 of the valves don't have the o-rings and backup rings, so I would disagree that they are identical.

A look at the parts book shows you they are all 4 the same valves. I have 4 new valves (in bubble packs) and the O-ring and back up rings are not on them. The difference is the sealing parts that get installed for based on the position the valve is used in during assembly.

 

[Weston Bend]

Great! I'm just trying to post a solution for another poor sap like myself who didn't know what he was doing.

 

[Tx Jim]

Attempting to adjust the clearances on those 4 valves by an inexperienced person will give one a new perspective on the word "difficult to adjust"!!!

 

[Jim.ME]

No one is trying to slam you, I'm glad you got it working as I am sure Tx Jim is as well. Like you we are just trying to help "another poor sap" who may decide to try undertaking this so that he isn't looking for two different valves in the parts catalog. The proper seals have to be installed on the valves for on the position they will go into.

The devil is in the details with these SCVs, which it appears you encountered as I read back through your posted experiences with it over the past few years. I admit to scratching my head at times over some of the same things you did the first time I did one. The technical manual, parts catalog, along with pictures and notes during disassembly are all part of my method now, as I don't do many of these valves and don't trust memory. I also check the flat machined surfaces by "stoning" them to check that they are flat with no raised threads or burrs to affect sealing. I have a couple more to due soon and decided it was time to purchase one of the jigs to hold the valves during adjusting the cams, hopefully it will make that step easier going forward.

 

[Tx Jim]

Yes I'm very glad Weston Bend got the scv operating correctly. I was just attempting to correct incorrect information when I read it so future readers wouldn't be mis-informed.

 

[wore out]

Yes I'm very glad Weston Bend got the scv operating correctly. I was just attempting to correct incorrect information when I read it so future readers wouldn't be mis-informed.

Also, for the record, the ENTIRE fiasco could have been avoided by simply removing only the actuating shaft and replacing a couple of O-rings vs. the major teardown.

The chance of a cracked housing in that area is miniscule, I would have replaced the O-rings and given it a try before even considering tearing down the SCV!