Bad Hydraulic fluid leak in rear end 648 BHL
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  1. #1
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    Bad Hydraulic fluid leak in rear end 648 BHL

    Have a leak where this large aluminum valve20201122_131248.jpg or what ever it it and the drive motor. It leaks almost steady drip under forward or reverse load. The fitting is tight, is there some seals or something for this crazy connection, see the close ups of the connection. Thanks for any and all feedback.
    Attached Images Attached Images

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  3. #2
    Dealer bhildret's Avatar
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    I presume your leak is right between the axle motor and the fitting installed to the motor. The schematic with the holding valve installation is shown here and the parts manual is in the tech forum stection.

    648 Axle Motor Connection.JPG

    The 'straight' fittings are SAE O-Ring boss fittings, so yes there is an o-ring in the bore of the motor to seal that fitting.

    The 'tapered' fittings are JIC #10, which rely only on the fitting angle and tube flare to seal. If those leak, they are either loose or need to be replaced (damage on one side or the other).

    Should be a simple fix, really. A bit of wrenching, but not much.

    Brian

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  5. #3
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    i see now the close up of the leaky fittings is not there. Please see the attached photo. I tried loosening everything and tightening the fittings in both the valve and the motor. the valve side could not break it loose, on the motor side i get a little tighter, so i tightened up the JIC and now it leaks way worse. I have to fix it. Also it looks to me the fittings may be reversed on my tractor? it looks like part 15 is on the holding valve side. I will try to get it apart, could you kindly tell me what parts 16 and 15 are? I can order them from you, just PM me. Thanks a bunch!20201122_131248.jpg
    Last edited by Bill_Allis; 11-22-2020 at 07:34 PM.

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  7. #4
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    found the parts list, the schematic you referenced is older version mine is 88, newer version i need 1 each 218-5254, 218-5006, 218-5406, and 218-5007, N9 holding valve ref. numbers 11-14

  8. #5
    Senior Member sdunt's Avatar
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    I had to go find my notes on this, because what the connectors are between the Holding valve and the motor is not obvious.

    Brian is right that where the fittings screw in to the motor and also into the holding valve, those are SAE O-ring fittings and the o-rings may be old. (IMO your tractors rear end possibly loose from the frame and moving around and flexing the fittings.. https://casecoltingersoll.com/showth...Mods-and-Rants)

    Both the Motor and the holding valve use SAE # 10 (O ring) fittings.. The connection in the middle between the holding valve and motor is a NPTF - Standard US PIPE on one side, that connects to a NPSM - National Pipe Straight Mechanical fitting on the other. I did not figure that out until I found the line in a fittings manual that says: "A properly chamfered NPTF male will also seal with a NPSM female."


    So that joint uses a 6900-10-08 - #10 SAE/ORB Male x 1/2" NPSM Female Swivel on the one side
    And a 6401-10-08 - #10 SAE/ORB Male x 1/2" NPTF Male on the other side.

    All of the other fittings in the motor and the holding valve (and the TCV outputs as well) are 6400-10-10 | 5/8" JIC Male x #10 SAE/ORB Male

    Jic connectors can become worn: https://casecoltingersoll.com/showth...rs-Tractor-age especially if things are moving.

    For the costs, I would replace, and I did on my '73 646, I would replace all of the connectors, which come with new o'rings.. Its less than $5 a fitting.

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    The piece in the middle is a JIC nut. It shouldn't be hard against the port adapter on the right, as the picture shows. Maybe a PO put the fittings on the motor backwards, or they're not JIC. The only other possibility is that, they have been tightened so hard, the nut cracked and is now split on the side we can't see.

  11. #7
    Senior Member sdunt's Avatar
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    Hydro, I will have to beg to differ with you on what the connection is. I agree it LOOKS from the outside like it might be JIC and Case used JICs all most exclusively on the tractors, but it is a NPTF to NPSM connection, Here are the connectors:

    HoldingValveFittings.jpgHoldingValveFittings2.jpg

    The RED painted fitting was in my holding valve when I bought it and that's NOT a JIC nut, the taper runs the wrong way. The 'china' fitting without the paint is a SAE to NPTF that honestly will thread up and seal with the swivel.. Weird as all ... if you ask me.

    I could not figure out what that fitting was until in the fittings manual on Page 3, I read:

    National Pipe Straight Mechanical (NPSM)
    This connection is sometimes used in fluid power systems. The female half has a straight thread and an inverted 30° seat. The male half has a straight
    thread and a 30° internal chamfer. The 30° seat of the female seals against the chamfer on the male. The threads hold the connection mechanically.


    A properly chamfered NPTF male (page 2) will also seal with a NPSM female.

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    Okay, but the intent of my comment remains the same. The nut, whether JIC or Npt internal cone (sometimes called NPT swivel), should not be hard against the other fitting (which should be like the unpainted China fitting you have shown). If most the fittings in Brian's drawing attachment are JIC, why would CASE use NPT on one fitting, but internal cone NPT is still a good solution. However it's easier to break the NPT nuts, and therefore they are often slightly heavier than the JIC of about the same size (ie. you use a 15/16 wrench for JIC and a 1" for NPT swivel).

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    Ordered up the fittings, i appreciate the help! SDUNT your the man, Everyone on this site is helpful!

  15. #10
    Senior Member sdunt's Avatar
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    I agree about the possibility of cracking the nut, regardless of type and your comment made me go back and look closely at those photos and yes, I would agree, that nut should NOT be tight up against that fitting in the motor.

    Quote Originally Posted by Hydrogeek View Post
    Okay, but the intent of my comment remains the same. The nut, whether JIC or Npt internal cone (sometimes called NPT swivel), should not be hard against the other fitting (which should be like the unpainted China fitting you have shown). If most the fittings in Brian's drawing attachment are JIC, why would CASE use NPT on one fitting, but internal cone NPT is still a good solution. However it's easier to break the NPT nuts, and therefore they are often slightly heavier than the JIC of about the same size (ie. you use a 15/16 wrench for JIC and a 1" for NPT swivel).

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