Thanks all for your experience and advice on rebuilding these things.

One thing that I can completely agree upon without doing the rebuild is that the ISO SCV's are crap. The design is just a rube goldberg hack.

So here's my second question: rather than change the JD-style couplers's over to ISO, what about going the other way? ie, take the ISO couplers off the 4640, go to a salvage yard and get some JD-style couplers and put them onto instead? Is this possible? And for a pull-off JD coupler package, how much should I be paying? The 4640 has three SCV's, and they're all ISO. I wouldn't shed any tears to convert them back to JD-style couplers; the 4440 has two SCV's, both JD-style and they just work better, IMO. I can either change tips on the equipment to use the Hesston 160-90, or I'll just buy adaptors and use them when I used the Hesston.

The couplers seem to leak the most when there is a tip in the coupler. One coupler (ISO style) leaks a bit even when there is no hose/tip in the socket. It leaks out the back side of the ISO coupling.

BTW -- here's an engineer's insight as to why the Deere ISO couplers are crap: Deere obviously had their own couplings, tips, etc. They were likely rather proud of them. I can see why -- they work pretty well. They break away pretty well. They don't leak and they're easier to couple with pressure in the lines.

One of the ways a big company with a considerable market share scuttles a "standard" is to do a crappy job implementing the standard. Then, when customers notice the "standards-based" product sucks in comparison to the proprietary product, the sales force says "Well, yes, but what can you expect? Standards cater to the lowest common denominator" and words to this effect. Been there, done that, got the t-shirt. In the big business scheme of things, it works... for awhile.