SCV leaking hydraulic fluid~
Installing the John Deere SCV coupler reseal kit is not an expensive job but it does require some patience. This page is specifically about repairing the Selective Control Valve (SCV) Couplers or quick disconnects (QD) on a John Deere 1640/2040 and many other models and installing the overhaul kit.
Problem/Symptom~ The hydraulic hookups are leaking, getting worse with time, making a mess and leaking hydraulic fluid.
Solution~ Order the JD Breakaway Coupler Overhaul Kit AR82570 and replace the seals. It is easier to work on if you can remove the unit from the tractor as shown above. You can cap off the ports of the SCV and use the tractor for other things while the QD is off.
The repair kit listed in my catalogue is for a John Deere 2040 Utility Tractor (Serial No. 350,000- ), but will work for many models.
Before starting I highly recommend watching the excellent Bundy Bears Shed–John Deere SCV Coupler Reseal video from Lance at Bundy Bears Shed in Australia. Very helpful. In his video he is working on a 4320, but the repair kit is the same. Of particular interest is his advice to first check the back of the coupler (Part #8) for burrs in case someone has hammered on it.
Above~ The SCV capped off on the tractor, what is in the repair kit, and the notice that comes with it (click the pic to enlarge). You use about half of what is in the repair kit because they give you the option of using V-Seals instead of some of the O-Rings and Backup Washers. If using the V-Seals, make sure the flat side is toward the oil side. I used the V-Seals but kept the spares just in case for later.
Diagrams~
Above and below~ I’ve included these in case they are of benefit to someone. Notice they are not showing all the V-Seals, but you can figure it out. IMO this looks a lot more complicated and intimidating than it actually is. It does however require some patience.
Beginning~
Above~ Using a punch to penetrate the soft metal caps to access the C-clip and spring. It just pops out, they give you new ones with the kit.
Below~ Removing the C-clips to access the springs. I was surprised how much gunk had got in there and was built up–tractor is almost 40 years old.
Above~ The spring that is held in place by the C-clip. Flat side goes to the bottom, clip on top. This frees up the valve lever (Part #24) for removal.
Below~ With the C-clip and spring removed the lever handle can be pulled out. Nothing will fall out at this point.
Above~ With the lever handle removed, the coupler unit itself can be pushed out from the back. The ball bearings will start to fall out, so you want to be able to catch them. Note the corrosion and gunk on the exposed part at the back. Don’t know if it was necessary, but I began keeping all left and right pieces separated.
After seeing all the gunk buildup everywhere I decided that Lance’s opinion in the video about removing the large snap ring and sleeve was a good idea. Although it isn’t necessary to just replace the O-rings and seals, it really is no trouble. These were badly weather/chemical marked, possibly from spreading salt, lime or fertilizer over the years. During reassembly I took pains to make sure the gap on all snap rings was facing bottom for drainage.
With the coupler removed, you can begin removing the V-seals in the coupler housing. There are four in total, pic shows one at the rear. I noticed they were fairly stiff, not iron brittle or anything, but nothing as flexible as the new ones. One of the ones I removed had the groove toward the oil side. I doubt if that was enough to cause a leak, but it was worth noting. Easy mistake to make.
I soaked the entire housing of the breakaway coupler in kerosene overnight. More gunk came out.
Below~ Removing the V-seals from the front of the coupler itself. There are two in total. These are slightly smaller than the four that are used in the housing unit, and have a grove on both sides. The rear (which you access after the snap ring and piston are removed) has an O-ring and white backup washer.
The Snap Ring~
I found it impossible to remove or reinstall the snap ring (Part #14) from the back of the coupler without depressing the piston. Without a proper press or valve spring compressor, the snap ring was a bugger to get out trying to hold down with a flat punch in one hand and screwdriver with the other. Eventually got it using a jerry-rigged c-clamp and bolt setup, but awkward to work around. A much better idea was what I came up with later with the drill press.
Public Service Announcement: Now here’s where I screwed up and maybe I can save somebody some grief. No matter what kind of press you have or come up with–after removing the snap ring but before you back off on the pressure, run your finger around the edge of the coupler end and check for burrs that might have been caused by removing that damn snap ring. Easy fix with some 220 grit sandpaper, then a blast of air to clean out. My first one came out fine, but my second one left a scratch/score down the piston when it was pushed out. It was a bugger to smooth out later.
Above~ This worked. My jerry-rigged drill press for reinstalling the snap ring, wish I’d thought of it before. Locked the handle down, took all of five minutes reinstall both new snap rings, which they give you in the kit. Later I looked at Valve Spring Compressors online. Most of them appear to have too large a stem–you would still have modify them. I didn’t see anything that would be an improvement over what is show above.
Removing the Piston~
Second Public Service Announcement: Although everything turned out fine, this was wrong. Instead of a flat end steel punch with a rag wrapped on the end, a person should be using a brass drift or even a piece of wood doweling to drive out the pin. Besides the ball bearing, if you damage the seat for the bearing inside the coupler you’re screwed.
Below~ Don’t do this. The piston with a score mark because I didn’t check the inside of the coupler end for burrs after removing the snap ring.
Back to the O-rings~
Above~ With the piston/pin out of the way–removing the O-ring and backup washer from the rear of the coupler. When it came time to replace them, I used the one piece V-seal they provided. There are two sets in total.
Below~ Removing the small O-ring and backup washer from lever handle ports of the coupler. There are four sets of these all together.
I found it helpful to put the removed V-seals, O-rings and white backup washers aside so you can count them after. You should have: 4 seals from the coupler housing, 2 smaller seals from the front of the coupler, 2 rear O-rings + backup washers from the rear of the coupler, and 4 small O-rings + washers from the lever handle ports. By doing so I discovered I had missed a backup washer for removal.
Cleaning~
With all seals, O-rings and backup washers removed from the housing and coupler–cleaned the inside of everything, including the ports, with a set of assorted brushes from Princess Auto. Without a bench buffer, I used mainly fine sandpaper and fine steel wool on the outside. I was a bit leary of anything too aggressive. Blew everything out with air after.
These cleaned up fairly well, but could have done better and easier with proper flat brass wire wheels instead of the cone shaped ones I had. Note score mark on piston, which I smoothed out best I could with a dremel tool and soft wire wheel.
Reinstallation~
Everything is reverse for reinstalling all V-seals, O-rings and backup washers. I’ll just show the one above, where the O-ring and backup washer at the back of the coupler is replaced with a V-seal. This is per the instructions that came with the kit (for a tractor built after 1970).
The holes for the ball bearings are slanted, so they will not fall out when the unit is held upright. A dab of grease holds them in nicely. Also a dab of grease on the piston spring to hold it in place before pushing it back into the coupler with the larger ball bearing is helpful and maybe even necessary. Once the sleeve is slid over the front of the coupler the ball bearings cannot go anywhere.
Below~ Ready to push back in. Machined flat side goes to the top for the spring and C-clip.
Couplers reinstalled. Despite my mistakes, no leaks at all. Real test came later with the round baler and both ports in use all day, no leaks. Nice without the mess.
Notes~
• During reassembly, grease is your friend. You need it to put a dab in the holes for the ball bearings, in the end of the pin/piston to hold the spring in place and so on. I like the Red and Tacky stuff from Lucas.
• A bench buffer with some soft steel and brass wheels for cleaning would certainly speed things up a bit.
• The mere fact that it was leaking hydraulic fluid at all probably means that the seals in the SCV are gone. It shouldn’t be leaking just because the tractor is on. This indicates to me that fluid is blowing past the seals in the valve itself, but that is a job for another day, a much bigger one I suspect.
• If you see errors in my recollections or have comments please leave them in the box below. Your email address is never shared.
• On my list from Princess Auto:
A set of brass drifts and a couple of flat brass wire wheels, coarse and fine.
