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Author Topic: overcooling condition  (Read 15168 times)

Offline Rough75C20

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overcooling condition
« on: May 19, 2025, 06:03:45 am »
Hello,

I replaced my thermostat this weekend due to it sticking and overheating. On the initial drive, temps were staying within a good range 180-210 degrees F. On the second drive, temp never increased above 150 degrees F. I believe the new thermostat got stuck open. I do have the housing with the temp sensor port, so I was going to open that and check to see if the thermostat is sticking up, but what could cause this? Do I need to flush the coolant out of the system and refill with all new? Not sure what would cause this as it was working normally on the first drive. No coolant is leaking from anywhere I can see.
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Offline Rough75C20

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Re: overcooling condition
« Reply #1 on: May 19, 2025, 09:01:47 am »
Also has anyone used the aluminum / silicone gaskets for the thermostat housing from amazon? Do they work better than the paper gaskets? any need for RTV with those.


Thank you
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Online VileZambonie

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Re: overcooling condition
« Reply #2 on: May 19, 2025, 01:21:10 pm »
No need to RTV the gasket. If you used a failsafe thermostat it probably failed.
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Offline Rough75C20

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Re: overcooling condition
« Reply #3 on: May 19, 2025, 02:23:31 pm »
It is a fail-safe thermostat. do these fail often when they shouldn't? Should I replace with a different brand? does the no RTV go for all thermostat gaskets (aluminum and paper)?
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Online VileZambonie

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Re: overcooling condition
« Reply #4 on: May 19, 2025, 03:23:21 pm »
Either use RTV or a gasket, there is no reason to use a gasket and RTV. Failsafe Thermostats are garbage.
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,                           ___ 
                         /  _ _ _\_
              ⌠¯¯¯¯¯'   [☼===☼]
              `()_);-;()_)--o--)_)

74 GMC, 75 K5, 84 GMC, 85 K20, 86 k20, 79 K10

Offline Rough75C20

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Re: overcooling condition
« Reply #5 on: May 19, 2025, 03:56:24 pm »
Thank you. Any recommended ones that aren’t trash right out of the box?


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Offline Rough75C20

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Re: overcooling condition
« Reply #6 on: May 19, 2025, 04:20:40 pm »
I guess what I am wondering is would it be better to get a balanced thermostat vs a regular spring piston type? Are they more reliable? Is it worth the extra cost?


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Offline Shifty

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Re: overcooling condition
« Reply #7 on: May 19, 2025, 05:30:19 pm »
The Robert Shaw unit has always worked well for me.
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Offline Rough75C20

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Re: overcooling condition
« Reply #8 on: May 25, 2025, 07:55:32 pm »
Just a follow up.

Went with a regular duralast gold thermostat and the aluminum / silicone gasket from Amazon. Working well with no leaks. Thanks guys. Was skeptical of the gasket at first but dry all around.


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