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Thread: Water pump is killing me

  1. #1
    Senior Member Parzival's Avatar
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    Water pump is killing me

    waterpump is killing me!
    I decided to replace my water pump. I have now taken it off 3 times, and gone through 2 new gaskets, and two different types of gasket sealer.
    I cleaned the mating surfaces really good and finished up with alcohol. Once dry I apply the gasket sealer and gasket, and bolt it toghether and let set over night, in this last case it sat for a 3 days. When I install it in the car I use the pressure checker and pump it up. It holds pressure for a few minutes, but after that I can see its dropping 1 or 2 PSI every few minutes. Spraying soapy water around I find bubbles around the water pump seal. What am I missing. After this last time I just can't imagine what else I could do to stop it.
    It is supposed to be able to hold this pressure for longer then a few minutes right? I haven't put any coolant in yet, is it just supposed to be water tight? and not air tight? Should I test with coolant in there? I just dont know

  2. #2
    Senior Member
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    What kind of RTV are you using on the gasket? Both sides?

  3. #3
    Senior Member Parzival's Avatar
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    Quote Originally Posted by dmcnc View Post
    What kind of RTV are you using on the gasket? Both sides?
    yes both sides. The first was grey silicone gasket sealer, and the second time I tried the Indian head gasket shellac.

  4. #4
    President, DeLorean Industries
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    Rtv is not right for this. You need to use hylomar to dress the gasket.

  5. #5
    Full of Eccentricities 81dmc's Avatar
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    I used rtv when I did mine, and AFAIK, I didn't have any issues with it.

    Parzival, if you want my Volvo spec, complete Gates pump with deloreanclubuk bolt on aluminum pulley, let me know. I'd gladly sell it to ya
    Rodolfo
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    Delorean Guru
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    When you pressure test you are supposed to fill the system with liquid (water and anti-freeze) and then pressurize the liquid. The liquid can seal tiny holes that air can leak out of and the pump seal needs the liquid to help it seal, it wont' seal tightly dry.
    David Teitelbaum

  7. #7
    Administrator Ron's Avatar
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    ??? Sounds like he was saying the gasket is ok now, ie, it only leaks air at the seal...

    If so, I'd suggest you fill it with water/coolant and check it.
    Did you let it run a bit before testing it (the last time)?


    Other thoughts:
    +1 J- A lot of gasket companies say not to use any sealant. You would be better off using nothing than using RTV (but I wouldn't do it over if it doesn't leak).

    You may have a leak somewhere else.

    Did you pressure check the cap?

  8. #8
    Senior Member Parzival's Avatar
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    Quote Originally Posted by Ron View Post
    ??? Sounds like he was saying the gasket is ok now, ie, it only leaks air at the seal...

    If so, I'd suggest you fill it with water/coolant and check it.
    Did you let it run a bit before testing it (the last time)?


    Other thoughts:
    +1 J- A lot of gasket companies say not to use any sealant. You would be better off using nothing than using RTV (but I wouldn't do it over if it doesn't leak).

    You may have a leak somewhere else.

    Did you pressure check the cap?
    I've never put the mixture unit back it, or put coolant in because both times it's not held air pressure at 15psi. I've only tried it with air only no coolant, This morning I pumped it up (with just air) and after a few minutes it was at 14PSI not 15, and then eventually like 10psi after like 5 minutes. Soapy water revealed air bubbles forming around the gasket. I can go add coolant and see if it holds, but then if it dosent I'm gonna have a mess on my hands.

  9. #9
    Senior Member AugustneverEnds's Avatar
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    Years ago I had trouble getting a leak free seal on my water pump. Upon close inspection I found a tiny chip on the mating surface of the original water pump back plate. I replaced it with a new one from DMC Europe. Also I had a tough time with the gaskets from the vendors, they're thin. I traced one onto a sheet of cork gasket material I picked up at Advance Auto and have had no issues for three years now.
    Nick A.

    1988 BMW 325is
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  10. #10
    Senior Member Parzival's Avatar
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    Quote Originally Posted by David T View Post
    When you pressure test you are supposed to fill the system with liquid (water and anti-freeze) and then pressurize the liquid. The liquid can seal tiny holes that air can leak out of and the pump seal needs the liquid to help it seal, it wont' seal tightly dry.
    You think I should put some coolant in there and try it?

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