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Thermostat Change

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thespartan0199

Freshman Member
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Hi All,
My thermostat failed and apparently I don't know what I'm doing because it was immediately seeping water at the housing slightly after I changed it.
I've never touched this on my car. When I took it apart it had the "original style" thermostat in there, 30+ years old. I decided to change with modern style.

I have the following new parts that I reassembled:
Brass sleeve
Small "thermostat gasket"
thermostat
thermostat housing gasket

What I read recommends the use of the sleeve; is this common practice?

What order should the parts and gaskets be assembled in? I put the small thermostat gasket under the brass sleeve which I thought made sense, but looking back now I have no idea if I assembled the parts and gaskets in the optimum order.

At this point I just want it to not leak.

1961 Austin Healey 3000

Thanks!
 
I assumed AI would have no idea, but it has a suggestion which differs from what I did, so I'll try this.

  1. Small circular thermostat gasket
    • Fits around the thermostat itself.
    • Common on many modern cars.
    • Not normally used on an Austin-Healey 3000 with the original thermostat housing and brass sleeve.
  2. Large thermostat housing gasket
    • Fits between the cylinder head and the thermostat housing.
    • This is the gasket you should use.

Correct assembly order​


From the cylinder head upward:

cylinder head
brass sleeve
modern thermostat spring down towards engine
large housing gasket
thermostat housing
 
Let us know how the AI suggestion works out. I've found a few AI tech answers to be spot on, but I always try to verify the details with a non-AI source.

Tom M.
 
I’ve never understood the purpose of the small round gasket. The housing holds the t-stat in place and the larger gasket seal the housing to the head. The small gasket seems like it’s worthless.
 
Rob Glasgow said:
I’ve never understood the purpose of the small round gasket. The housing holds the t-stat in place and the larger gasket seal the housing to the head. The small gasket seems like it’s worthless.
Click to expand...

I think it's there to (theoretically) seal around the thermostat so coolant doesn't leak past it. I also think the amount of coolant that could 'leak' is inconsequential; if I have one I'll install it, if not I don't lose any sleep over it. The seem to dissolve eventually anyway.
 
Check thermostat housing for any signs of pitting from corrosion. A pitted housing around sealing surfaces could cause sealing issues. A thin coat of RTV usually stops the leak/weep.
 
How do you know the old one failed? What were the symptoms? Did the car suddenly overheat, or did it spring a leak & if so where was the leak?

You say you changed from "original style" to "new style" - do you have pictures? Did you put the old one in a pan of water and bring it to a boil to see if it still worked? There should be markings on the old one to indicate the temperature it was designed to open - 160, 170,180, 190, etc. & with a candy thermometer and your thermostat in water, you can test to see if it is still within spec.

As to the gasket choices, you are trying for two things - no leakage to the outside, and no leakage thru when the thermostat is closed (obvously the less critical of the two).

Anyway, pictures can go a long way to helping solve any riddle.
 
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