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79 308GTB Water Pump Question

Discussion in 'Technical Q&A' started by christopher, Jan 24, 2004.

  1. christopher

    christopher Formula 3

    Nov 29, 2003
    1,131
    Ontario California
    Full Name:
    Christopher
    Gentlemen,

    Is it advisable to use "Permatex" (silicone) on water pump parts when installing a new water pump and a new rear housing? As I took off the old units, it was apparent that no silicone was used. Thank you, Chris.
     
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  3. pma1010

    pma1010 F1 Rookie

    Jul 21, 2002
    2,559
    Chicago
    Full Name:
    Philip
    Base gasket between the 2 housing sections takes gasket, no sealant.

    O ring takes silicon.

    Internals - sorry, Tod did mine. I would think so, but wait for someone to post that's done a bunch.
    HTH
     
  4. Verell

    Verell F1 Veteran
    Consultant Owner

    May 5, 2001
    7,002
    Groton, MA
    Full Name:
    Verell Boaen
    My '82 308 WP had the characteristicly red RTV that Ferrari uses on both the WP nose-body gasket, & o-ring joint. It was used very sparingly, more like a dressing.

    When I R&R water pumps I use Permatex's coolant & waterpump RTV. It's grey & claimed to have much higher water & coolant resistance than std RTV. Just use a very thin smear as a gasket dressing.

    Also use a thin smear on the bottom of the ceramic seal rubber mounting & on the shaft's seal mounting area. (DO NOT GET ANY ON THE FLAT SEAL SURFACES, coolant must wet both seal surfaces as the seal depends on surface tension. if you accidently do, clean it off thoroughly w/brake cleaner or lacquer thinner, then wet w/coolant to make sure it forms a film. If it beads, clean some more...)

    Shouldn't be necessary for the nose-body gasket if both surfaces are smooth. However, reality is that over the years one of both of the surfaces will have acquired some scratches from gasket scraping, etc.

    If you've got the wp out & apart, you can smooth the surfaces by removing the studs & using a large flat block of wood & 280 grit sandpaper followed by 400 grit. Just don't take much off as the impeller clearance is pretty tight.
     
  5. Peter

    Peter F1 Veteran
    Rossa Subscribed Owner

    Dec 21, 2000
    6,406
    B.C., Canada
    Would Hylomar work as well? I got a tube of it recently (made by Permatex actually) and they claim it can be used on water pumps (will be doing my pump too, sometime this winter...). I bought it for use on other components on the engine, but could use it in this instance if other people have had success using it for this application.

    The claim is that Hylomar is good for future removal of the component without damaging the gasket, yet still seal, like ordinary sealant.
     
  6. christopher

    christopher Formula 3

    Nov 29, 2003
    1,131
    Ontario California
    Full Name:
    Christopher
    To all that responded to my question Re: Silicone usage on water pump.
    Thank you very much!

    Chris.
     
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  8. 4re gt4

    4re gt4 Formula 3

    Apr 23, 2002
    2,279
    Roseburg, OR
    Full Name:
    Hans E. Hansen
    Peter: I've recently been using Hylomar and have been very impressed. A friend who builds racing engines uses it exclusively. Beware of getting it on too thick, tho, as it definitely will ooze (squish) out. This shows itself in bolts that you have to re-torque. (Torque OK, come back tomorrow, and they're loose!) Just the very thinnest coating is fine. However, unlike silicon, if you do boo-boo and goop it on, it usually will do little/no harm, as it doesn't harden.
     
  9. Peter

    Peter F1 Veteran
    Rossa Subscribed Owner

    Dec 21, 2000
    6,406
    B.C., Canada
    Thanks. I'm always careful with application of sealants- I smear a thin coat on, then smear some more off.
     
  10. Verell

    Verell F1 Veteran
    Consultant Owner

    May 5, 2001
    7,002
    Groton, MA
    Full Name:
    Verell Boaen
    Hmm,
    I often use Hylomar to keep o-rings in place during ass'y, unlike RTV, it's tacky & keeps things in place. RTV & o-rings are bad news. It lubricates them & they'll squeeze out of place given the least opportunity(don't ask)... MAZDA recommends it in a lot of places in re-assembling an Rx7's engine.

    Also use it as a gasket dressing, where I think I might want things to come apart later (eg: cam cover gaskets.) A little does go a long way, & it does squish out a bit.

    If Permatex says it's ok for WP's, then IMHO it's OK use.

    BTW, Your RTV philosophy sounds right on. Less is generally better.

    Hmm, I think I still lean towards a film of RTV for mounting the seal into the housing & sealing the other seal halfto the shaft. I want something that sets up there.

    BTW,It really isn't hard to get the RTV off again if you use a brass brush, either by hand, or a small one in a drill or Dremel type tool. Brass won't damage the Aluminum.
     
  11. Peter

    Peter F1 Veteran
    Rossa Subscribed Owner

    Dec 21, 2000
    6,406
    B.C., Canada
    After cleaning the traces of corrosion out of the recess in the pump body for that one half of the seal, I had an incredibly difficult time inserting that into the body afterwards. I used water as a lubricant to help because it was impossible doing it dry. I'm confident its sealed now (exerted pressure, smooth pit-free aluminum and soft rubber), but since you mentioned RTV's slippy properties, I'll try that next time... Hopefully years from now.

    Looking at the shaft though, I'm definitely putting some sort-of sealant there. Knew right from the start.
     
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