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96 C4 running hot.

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Old Mar 20, 2025 | 09:39 PM
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Default 96 C4 running hot.

Good Evening. I replaced the HVAC Heater flow control valve on my 96 Vette, which is still running hot. I'm not sure if the T-stat is bad. I haven't tried the bleeder screw yet to purge the system. Any advice would be appreciated.

P.S. This is my first attempt at working on this vehicle.
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Old Mar 20, 2025 | 10:35 PM
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Moved the thread to the C4 Tech section for assistance.
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Old Mar 20, 2025 | 11:46 PM
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Originally Posted by Redwayne63
Good Evening. I replaced the HVAC Heater flow control valve on my 96 Vette, which is still running hot. I'm not sure if the T-stat is bad. I haven't tried the bleeder screw yet to purge the system. Any advice would be appreciated.

P.S. This is my first attempt at working on this vehicle.
The usual problem is a Vette is like a highway trash collector, check between the radiator and condenser for leaves and plastic bags. Then fit a screen at airdam to keep it from happening in future, the other could be a temp sender showing high or thermostat starting to fail.

Check the radiator temperature, those infra red temp gauges you can point at radiator are cheap and a great help, ensure the cooling fans work run the air-conditioning to check the fans come on.

Good luck 🙂👍
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Old Mar 21, 2025 | 03:13 AM
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I sugest you read the Sticky Corvettes, Summer , and High Coolant temperatures in the C4 General Forum
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Old Mar 21, 2025 | 07:09 AM
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I had one (94) in the shop last summer that was running hot going down the road and after cleaning the radiator and checking flow I removed the t stat. I found that the bottom disc was gone. I put a new 180* stat in it and it was fine. Not sure where the disc went.
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Old Mar 21, 2025 | 09:59 PM
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Welcome!!
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Old Mar 22, 2025 | 12:54 PM
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The missing disc is on a quest to find all the 10 mm sockets

Originally Posted by ex-x-fire
I had one (94) in the shop last summer that was running hot going down the road and after cleaning the radiator and checking flow I removed the t stat. I found that the bottom disc was gone. I put a new 180* stat in it and it was fine. Not sure where the disc went.
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Old Mar 22, 2025 | 01:19 PM
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I would check stat. just put in a pot of water bring it up to a boil see if it is opening, if not need a stat , that's the first thing I would check .. There are a few other people having the same problem in this tech deal, just click on them find the one with the list, there is a possess no other way to do that I know about, check the fans see what temp coming on going off, no trash in the radiator inside or outside, the org. radiators over the years can have built up in them , AIR in the system that's a big one ,I just leave the cap off it will bleed from the cap just have to watch it when the bubbles stop should be good ,The fix may be easy finding it not so much .. Start with this list and if not fixed keep digging, I never found a magic bullet when it comes to a C-4 overheating, I just replace everything with new heave duty stuff, but that's just me ..
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Old Mar 27, 2025 | 07:35 PM
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Thanks for your response.
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Old Apr 5, 2025 | 12:05 PM
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