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Thread: O-ring sizes

  1. #1
    Super Moderator Turbo Mopar Staff 135sohc's Avatar
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    O-ring sizes

    Cant believe we dont have this pinned somewhere ?

    The o-ring for the water pump housing to block and the aluminum t-stat housing to head. Does anyone know the size of these or have one handy to measure ? And the o-ring for the 8v distributor ? I dont have either one loose to measure and would like to get a bag of each for stock.

    Thanks!
    1994 Shadow Sedan. 2.2 N/A, A568 400,000 miles. "the science experiment"
    1987 Shelby CSX #418. Long term rebuild and restore ?

  2. #2
    Supporting Member Turbo Mopar Contributor
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    Re: O-ring sizes

    I have a number of water pump o-rings they are 9/64 or 3.5mm wide, I measure the ID as 1 7/8" and 2" OD
    This is not a standard 225 o-ring and a quick look did not match the standard metric o-ring either.
    For reference I measured the gap
    54.23mm x 44.3mm x 2.5mm deep

    This can help verify the correct o-ring
    http://solutions.parker.com/ORingSelector
    Regards,
    Miles

    DD '87 Sundance T1, SLH with rear disks
    '87 CSX #432 2.5 CB TII, SLH

  3. #3
    Super Moderator Turbo Mopar Staff 135sohc's Avatar
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    Re: O-ring sizes

    I noticed the supplied o-ring always seemed a size smaller than it should be. That would explain it.
    1994 Shadow Sedan. 2.2 N/A, A568 400,000 miles. "the science experiment"
    1987 Shelby CSX #418. Long term rebuild and restore ?

  4. #4
    Supporting Member Turbo Mopar Contributor
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    Re: O-ring sizes

    Quote Originally Posted by 135sohc View Post
    I noticed the supplied o-ring always seemed a size smaller than it should be. That would explain it.
    interesting that I felt the same but never did anything about it
    Regards,
    Miles

    DD '87 Sundance T1, SLH with rear disks
    '87 CSX #432 2.5 CB TII, SLH

  5. #5
    Supporting Member Turbo Mopar Contributor
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    Re: O-ring sizes

    So.. I decided to check what o-ring is recommend for the application. Since we use Parker lots at work (Scientific Instrumentation) used their on line tool.
    We have a "Face Seal internal pressure https://promo.parker.com/promotionsi...ace-Type-Seals
    Water pump housing groove is 2.135 OD 1.744 ID and 0.1 deep so groove width is 0.1955 (2.135-1.744)

    Here is the area to determine o-ring size https://www.parker.com/literature/O-...l%20glands.pdf
    https://www.parker.com/literature/Pa...g_Handbook.pdf
    Since the gland depth 0.1 I choose the 200 series and the groove width is close to that recommended with the 200 series as well
    With internal pressure sealing we select the OD as the critical measurement thus the 225 should work
    225 is 1/8 x 1 7/8 x 2 1/8

    A metric o-ring may fit better but I doubt Mopar would design for a more expensive o-ring.
    Regards,
    Miles

    DD '87 Sundance T1, SLH with rear disks
    '87 CSX #432 2.5 CB TII, SLH

  6. #6
    Super Moderator Turbo Mopar Staff 135sohc's Avatar
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    Re: O-ring sizes

    The hardware store had 224 in their selection, no 225. The 224 is just barely a stretch fit to sit in the groove and I would wager to guess is the size that comes with a new pump and the size if one bought an o-ring À la carte by application from the store.

    mcmaster has a dizzying array of options available.
    1994 Shadow Sedan. 2.2 N/A, A568 400,000 miles. "the science experiment"
    1987 Shelby CSX #418. Long term rebuild and restore ?

  7. #7
    Supporting Member Turbo Mopar Contributor
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    Re: O-ring sizes

    I read up on the engineering of flange o-ring seals from Parker this AM. For external pressure the inside seal is important, So your 224 maybe a good fit for this application.
    For internal pressure application like our water pump the important seal is the OD so a 255 would be much better for the application.
    I checked my supply of water pump o-rings and the are very close to contacting the OD of the flange groove, which is good
    I have orings by application and they are a larger cross section than the 225 (225=0.125 vs my oring at 0.138)
    Personally I am planning to stay with the 0.138 as I know they work for me.

    I did find a Oil-Resistant Buna-N O-Ring, 3.5 mm Wide, 46 mm ID that better matches my stock
    Last edited by chromguy; 02-29-2020 at 02:22 PM.
    Regards,
    Miles

    DD '87 Sundance T1, SLH with rear disks
    '87 CSX #432 2.5 CB TII, SLH

  8. #8
    Super Moderator Turbo Mopar Staff 135sohc's Avatar
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    Re: O-ring sizes

    To follow up with this. I ordered some 225's and fit checked against a NOS water pump housing was satisfactory.
    1994 Shadow Sedan. 2.2 N/A, A568 400,000 miles. "the science experiment"
    1987 Shelby CSX #418. Long term rebuild and restore ?

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