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Stuck thermostat housing

Discussion in 'Technical Q&A' started by FasterIsBetter, Aug 19, 2025.

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  1. FasterIsBetter

    FasterIsBetter F1 Veteran

    Jul 22, 2004
    5,856
    NoNJ/Jupiter FL
    Full Name:
    Steve W.
    #1 FasterIsBetter, Aug 19, 2025
    I'm working on my son's 1982 Mondial 8. The thermostat needs to be replaced, which should be easy. I've done many of them. But I don't think the thermostat has been changed since it left the factory and the housing cover is stuck and won't budge. Any suggestions on how to get the cover loose would be appreciated. We got the nuts off but it's almost like the cover is welded to the base. We don't want to break it. We are going to try heat, but need to be careful with that as there are a lot of things around there we don't want to melt. Thoughts? Thanks in advance.!

    SteveW
     
  2. Rifledriver

    Rifledriver Three Time F1 World Champ

    Apr 29, 2004
    37,288
    Cowboy Capitol of the World
    Full Name:
    Brian Crall
    #2 Rifledriver, Aug 19, 2025
    Heat is a good choice. Get it very hot and hammer upwards on the water neck with a compothane or similar hammer.
     
  3. moysiuan

    moysiuan F1 Rookie
    Silver Subscribed

    Nov 1, 2005
    4,237
    Canada
    #3 moysiuan, Aug 19, 2025
    The problem is the studs. Coolant weeps from the bleed screw when bleeding, goes under the nuts and down the stud. Gets the galvanic corrosion going, and the aluminum "welds" itself to the steel studs. Put some penetrating oil on the studs and let soak for a few days. Then some heat. Plastic hammer to whack things and try to break the corrision.
     
  4. Ferrari Tech

    Ferrari Tech Formula 3

    Mar 5, 2010
    1,229
    Georgia
    Full Name:
    Wade Williams
    #4 Ferrari Tech, Aug 20, 2025
    I have had the same issue on several cars. I have actually broken one that would not come off. A replacement was easy to get, so if it breaks don't panic, it is not that bad.
     
  5. Rifledriver

    Rifledriver Three Time F1 World Champ

    Apr 29, 2004
    37,288
    Cowboy Capitol of the World
    Full Name:
    Brian Crall
    #5 Rifledriver, Aug 20, 2025
    Actually it oozes around the gasket and up the studs exactly the same as the head studs get corroded and make the heads difficult to get off.
     
    Ferrari Tech likes this.

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