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Subject: NAA piston pump O-rings choice

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BlasterStumps    Posted 01-26-2024 at 10:16:52 [URL] [DELETE]        [Reply] [Email]  
  • NAA piston pump O-rings choice
  • Probably did it wrong.
    I am in the process of changing out a vane pump on the NAA to a piston pump. I have the pipes that go with the piston style pump. I am wondering if I am using the correct "O-ring" in the grove of the pump. The kit I got had several sized round style o-rings and some square shoulder o-rings. Seemed to me that the o-ring that fit the best in the pump was the square shoulder style. I put it together last night but have not put the oil back in so I can take it back apart if needed. Whatcha guys think? Did I choose the wrong one for the pump. The square shoulder style that I put in the pump did not fully fill the machined groove. The rounded style in the kit seemed either too large or too small. If I put the oil in and get the tractor running, I can test it but then if it is not correct, I will have to drain it out again.

    Tim Daley (MI)    Posted 01-27-2024 at 11:22:29 [URL] [DELETE]        [Reply] [No Email]  
  • Re: NAA piston pump O-rings choice
  • JUST8Ns sells a hydraulic manifold O-RING kit --- SEE LINK if this helps.

    MPC shows O-RING p/n EAF-990 as well.

    If you have your old O-RING, you can measure the ID, OD, and diameter of ring with dial calipers and find a match from any supplier. Try McMaster-Carr:


    Tim Daley (MI)

    Tim Daley (MI)    Posted 01-27-2024 at 05:55:43 [URL] [DELETE]        [Reply] [No Email]  
  • Re: NAA piston pump O-rings choice
  • The correct parts for the NAA HYD Piston, Wiper, and O-Ring are:

    NAA-533-A O-RING

    ALL will also work on the 9N/2N & 8N Hydraulic Systems as well. The NAA piston was a better design than the original 3-Steel Ring Piston style. The Rubber O-RING is supposed to encroach a bit externally out of the piston groove to help form a seal. The leather back-up washer/wiper helps clean any debris when moving in and out. There is a neoprene wiper supplied by CNH, p/n 87051231 as shown, that some have used in place of the leather wiper. The jury is still out, (show me the data) if this was a better design or not. I've rebuilt several N's using the NAA parts with both the OEM
    Leather Wiper and the CNH Neoprene Wiper with satisfactory results using both. I also recommend you spring for a new cylinder as well when rebuilding your system. An old worn out cylinder will only create headaches and you don't want to keep pulling the top cover and redoing it do you?

    I can't verify if the CNH Wiper is still available or not, suggest you call your local CNG dealer first. You may have to special order it. Your call on what you want to use but these parts are right and all except the CNH wiper available at JUST8Ns.

    CNH NEOPRENE WIPER, p/n 87051231:

    Tim Daley (MI)

    Dean    Posted 01-27-2024 at 08:17:51 [URL] [DELETE]        [Reply] [No Email]  
  • Re: NAA piston pump O-rings choice
  • OP not asking about lift cover parts but, rather, O rings for hydraulic manifold at pump.

    Tim Daley(MI)    Posted 01-27-2024 at 11:01:58 [URL] [DELETE]        [Reply] [No Email]  
  • Re: NAA piston pump O-rings choice
  • 10-4


    BlasterStumps    Posted 01-27-2024 at 15:42:51 [URL] [DELETE]        [Reply] [Email]  
  • Re: NAA piston pump O-rings choice
  • Thank you Tim.

    Dean    Posted 01-26-2024 at 13:07:16 [URL] [DELETE]        [Reply] [No Email]  
  • Re: NAA piston pump O-rings choice
  • Do yourself a big favor and use the correct square-cut O rings from CNH. Yes, they will almost certainly need to order them.

    Be certain that the correct O rings are properly positioned and DO Not overtighten.

    BlasterStumps    Posted 01-26-2024 at 15:11:42 [URL] [DELETE]        [Reply] [Email]  
  • Re: NAA piston pump O-rings choice
  • Hi Dean,
    We don't have CNH dealers close. I was wondering if you know of a good dealership to try for the o-ring you mentioned.

    Ed Gooding (VA)    Posted 01-27-2024 at 06:50:45 [URL] [DELETE]        [Reply] [Email]  
  • Re: NAA piston pump O-rings choice
  • Mike, I would also check with Messick's for what you need.

    TheOldHokie    Posted 01-27-2024 at 16:14:27 [URL] [DELETE]        [Reply] [No Email]  
  • Re: NAA piston pump O-rings choice
  • According to Messicks parts page the o-rings are standard AS568 o-rings. Dash size and hardness:

    -214, 70 durometer for pressure
    -216, 70 durometer for suction

    You can get them in round, square, or X profile.


    BlastersStumps    Posted 02-01-2024 at 20:57:25 [URL] [DELETE]        [Reply] [Email]  
  • Re: NAA piston pump O-rings choice
  • Thank you TOH. Got the O-rings coming. I've tried nearly everything under the sun to get the dang thing to quit leaking but nothing has worked so I sure hope these seals from Messicks will do the trick.

    You all are great folks and I sure appreciate the help.
    Mike in CO

    BlasterStumps    Posted 01-27-2024 at 15:45:15 [URL] [DELETE]        [Reply] [Email]  
  • Re: NAA piston pump O-rings choice
  • Thank you Ed. I will give it a try.

    Dean    Posted 01-26-2024 at 20:07:38 [URL] [DELETE]        [Reply] [No Email]  
  • Re: NAA piston pump O-rings choice
  • Though probably available from others such as Graingers, you would need dimensions and would likely need to order an entire box.

    Bite the bullet and order from Messicks, a CNH dealer who does sell on internet.

    BlasterStumps    Posted 01-27-2024 at 15:44:01 [URL] [DELETE]        [Reply] [Email]  
  • Re: NAA piston pump O-rings choice
  • Thank you Dean

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