Heating on idle
Melting Slicks
Joined: Oct 2003
Posts: 2,189
Likes: 830
From: Chapel Hill NC
2025 c3 ('68-'73) of the Year Finalist - Unmodified
2025 C4 of the Year Finalist - Unmodified
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I suggest you read the sticky in the C3 general section entitled Corvettes,Summer, and high Temperatures
Last edited by pltmgr; Jan 21, 2026 at 09:57 AM.
Racer
Joined: Sep 2017
Posts: 378
Likes: 93
From: Alaska
This too.
In addition, I found when my "radiator cap" (on the pressure tank) went gunny sack, it not only ran hotter, but it would barf coolant into the recovery tank after the engine was off.
Drifting
Joined: Nov 2018
Posts: 1,800
Likes: 579
From: Mays Landing, NJ
Replace the radiator cap. It may not be holding proper pressure which will cause coolant to flow into the overflow tank and overflow out of it.
Its a cheap part and you'll know immediately if that was the problem. Of course you also need to determine if the fan(s) are indeed coming on at proper temps.
Its a cheap part and you'll know immediately if that was the problem. Of course you also need to determine if the fan(s) are indeed coming on at proper temps.
