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Removing the Valve Stack 8670

F

FOMOCO Farmer

Member
Last December I bought a NH 8670. It had lots of codes, no brakes, just needed some TLC. We replaced the brake piston seals and rebuilt the master cylinder. Spring came and nothing else was done. The tractor has been sitting for 9 months. We've picked up more farm ground and will be needing this tractor. Upon the advice of all that I have talked to, the general consensus is the valve stack on the back needs rebuilding. I tend to agree. So, yesterday, the task was started! Fair warning, I will be needing all help, advice, moral support, butt chewing associated with getting this tractor back in running order. I have the repair manuals. Thanks!
 
Those valve stacks aren't too bad to pull off. Be advised that you don't need to tear them completely apart, since you're only going after the seals on the shuttle check valves for the load sensing system.

Whatever became of the TW25 with no oil pressure? Did you decide to park that for 9 months too?
 
Thanks Bern! Ha, the TW25 is the last tractor to break down. Therefore, it's the last one to be repaired! There is a TS115A in my shop now. It's the one that was losing water. Next is another 115A that needs a hydraulic pump. Then a TW20 that needs a hydraulic pump. A TS 125A is at a local shop with electrical problems. Harvest got in the way of repairs. Tomorrow a new shop building kit arrives. New shop will be heated, well lit, etc. I've been wanting a nice shop my whole life! Sold all the cows, will not be feeding in the bad weather. I'll be working in the shop where its warm!
 
I got the valve stack off today. I have it apart. What should I be most concerned with? I noticed in the remote bodies there are some springs you can see. Some of these are broken. I know that needs to be addressed. Thanks!
 
Using the link below, you want to focus on the shuttle checks #2 and 4, along with the associated seals (2A, 2B, 2C, etc.). Also take note of the #56 item called a shuttle improvement kit for the 3-point lift section.

In the image below, the shuttles are #6 and #7. These are the usual trouble areas. I'm guessing you'll find either missing and/or torn o-rings.
cvphoto142798.png

Remote valve
 
Sounds like you got a lot of worked stacked up, which is a good thing in this case because you'll be able to justify your new shop, either to yourself or your significant other.
 
We took the one remote valve apart yesterday. We removed the spool and small steel balls fell out. This is #19 in the parts breakdown. I'm guessing we shouldn't have removed the spool. Upon removing #2, we found no O-rings present on that part. I think that's the area we should be concerned with. #19 is called a plate, hopefully I can order a replacement. Is there any need of removing the spool from the other valves or just #2? Thanks!
 
All the little balls fell out....yep, this is why I said you don't need to take the valve completely apart, but rather focus on only the shuttle valves. Don't mess with the main spools! Use vaseline to hold the balls in place when you put them back in their spots.

If you found no seals on part #2, you found the problem. Done deal, case closed. Be sure to check those same shuttles on all of the other valves.

#19 is a bunch of ball bearings. Not sure why you're calling them a plate???
 
The parts book called it a plate. We used some wheel bearing grease to hold them in place. Parts book says 8 we found 7. I'll get enough balls and Vaseline. My dad always used Vaseline when he assembled a Selecto Speed! Lesson learned!! Experience is the best teacher if you can afford the tuition!!
 
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