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Thermostat stuck open?

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Old Apr 10, 2026 | 03:01 PM
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Default Thermostat stuck open?

My GS has been showing the "yellow" on the tach, for a while. Comes and goes. Even when fully warmed up and esp. on the highway (unless I'm revving high). The temp is usually ~170, even when the yellow disappears. I think it's supposed to be 180-220. So, seems the thermostat is stuck open. I've replaced them on other cars, but never on my Corvettes. Advice? Easily done? Thanks.
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Old Apr 10, 2026 | 03:35 PM
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Easy Peasy. Just make sure you get the correct temp spec. What car do you have?
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Old Apr 10, 2026 | 05:45 PM
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Classic bad thermostat symptoms. Rock Auto sells the whole housing at a good price.
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Old Apr 10, 2026 | 06:48 PM
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Originally Posted by kodpkd
Easy Peasy. Just make sure you get the correct temp spec. What car do you have?
2017 C7 Grand Sport

Should I care whether it's GM OEM or aftermarket? (Motorad, Aisin, etc.) The price difference doesn't seem to be that significant.

Last edited by IAIA; Apr 10, 2026 at 07:00 PM.
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Old Apr 10, 2026 | 08:59 PM
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Originally Posted by IAIA
My GS has been showing the "yellow" on the tach, for a while. Comes and goes. Even when fully warmed up and esp. on the highway (unless I'm revving high). The temp is usually ~170, even when the yellow disappears. I think it's supposed to be 180-220. So, seems the thermostat is stuck open. I've replaced them on other cars, but never on my Corvettes. Advice? Easily done? Thanks.
When I replaced mine a few months ago I used went to Rockauto, they hade the best price, It is pretty simple, here is a link to the thread I started when I needed to replace mine, lots of good info and pictures.
https://www.corvetteforum.com/forums...s-done-it.html
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Old Apr 10, 2026 | 08:59 PM
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Originally Posted by IAIA
2017 C7 Grand Sport

Should I care whether it's GM OEM or aftermarket? (Motorad, Aisin, etc.) The price difference doesn't seem to be that significant.
OEM is your best choice. Best place to buy, Rock Auto.
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Old Apr 11, 2026 | 07:13 AM
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Always OEM!
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Old Apr 22, 2026 | 04:26 PM
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Since the "other" thread of late that included R/R of the thermostat, I can say here that I just finished replacing mine. As mentioned, easy-peezy. This forum has always rocked with the helpful tips and information. Couldn't have done it without y'all. Thanks.
UPDATE: took it for a test drive and pushed it to see how the temp would adjust. No yellow on the tach after about 2 minutes, and rock solid 195 degrees.

Last edited by IAIA; Apr 22, 2026 at 08:03 PM.
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