Remote Valve Rebuild 8670 Bern

We got back to rebuilding the remote valves today. The #2 shuttle check in all three valves had no 0-rings present. Upon installing the O-rings and back up rings we discovered there is not enough space for an
O-ring and back up ring in the grooves they go in. What would you think is the problem?
You mentioned shuttle check #4. We have not attempted a teardown of this valve. Do you think we should?Thanks!

Are you trying to use kit o-rings or the proper ones supplied by NH/Rexroth? Those are a metric D-90 ring. If you use something too soft or too fat they just cut when you put them in. If they're too small they leak.
Generally speaking, the most common problem you will find in those valves is broken/missing o-rings on the #2 primary shuttle. There could also be a bad o-ring or missing ball on the #4 secondary shuttle. Normally you would go through all of them with the stack in place, ideally... and if that doesn't fix the problem then go digging further.
Only other piece of advice I can give you is use the right o-ring. If they get stuck in the internal passages of the shuttle ports towards the flow control valve you could have a fair amount of misery doing tear down and extracting them. Generally you should not need to get into the spool itself or the internal flow control unless you know you have port leakage in the valve.
Also, FYI, if you do happen to need parts, you may find a local hydraulics dealer that deals in Rexroth stuff, particularly plow truck hydraulics. These are MP18 banks that are used on many municipal plow truck setups as Rexroth also provides the salt computers. That said I've found NH has the best availability...

Rod

Rod gave some good advice. In addition, I believe there was an update to the shuttle valve o-ring grooves that made them wider to accommodate the back-up ring. My suggestion is that it would be better to replace the entire shuttle check valve to allow you to install both the back-up ring along with the o-ring.

And yes, by all means, do check the #4 shuttle valves as well. They are just as much susceptible to this kind of failure.

Thanks to both of you! I'm probably making this harder than it really is. Upon talking to other experienced mechanics, there seems to be a kit for the shuttle check valve. Seems you get the check valve and all o-rings to rebuild one valve. As stated, you do this on the tractor starting from the bottom. I looked up the kits. My tractor has 3 remote valves. There are no less than 6 kits available depending on which valve I have. How do I know which one to order? My serial number is D411132. My dealer nor I have any experience with these tractors. The learning curve is steep and expensive! I keep telling myself that one day it'll be fixed and I'll have a good tractor.

If it were me I'd order some balls for the secondary shuttle 9672608 and their respective o-rings along with the primary shuttles 86019463. I only see one number listed for each. Also, if you have the stack apart, order the o-rings and particularly the shims for the stack as they seem to vanish easily.
There are a multitude of shuttle valves fitted by rexroth for other applications ie. single acting, motor spools, etc but all I see for genesis applications use the standard double acting shuttle. There may be product progression updates to numbers over time but I'd expect they are all backwards compatible. Don't over think this. It really is pretty straight forward. Either put some new rings on the shuttles you have or replace them. Your call as they're a couple hundred each. Just watch that the joint in the shuttle isn't worn out. If that starts to leak you'll have problems. You can also try these guys for after support if you don't want to go through a dealer. I suspect this is where CNH gets parts today since Rex no longer support the valve.

Rod
MP18 valves

(quoted from post at 06:17:59 12/22/22) You can also try these guys for after support if you don't want to go through a dealer. I suspect this is where CNH gets parts today since Rex no longer support the valve.

Click to expand...

Thanks for the link. It's been a while and I didn't know the parts source had changed.

I disassembled all three valves yesterday. Washed, blew air in all the ports, and sprayed with brakleen. I ordered the shuttle valves, shims, o-rings, and balls to rebuild the valves. I won't be working on it today. Hopefully will get back to it next week. Thanks to all that have helped! Merry Christmas!