C4 runs hot

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Dec 20, 2025 | 12:36 AM

#21

Steve Swan

1994 LT1 1996 LT4

Joined: Sep 2024

Posts: 772

Likes: 730

From: East Front Range Colorado

Quote:

Originally Posted by dburgjohn

just got to mention DeWits radiators. My 1992 runs 195 in summer with AC on full. What a difference it made.

@dburgjohn thanks for mentioning you're running a Dewitts. I didn't mention in my posts that I am also running a Dewitts Direct Fit. I opted to replace the factory radiator because 1/3 of it was so plugged up the sun did not shine through and i didn't want to risk it springing a leak if the sealing rings on either side failed.

Dec 22, 2025 | 07:25 AM

#22

llapine

Cruising

Joined: Jul 2024

Posts: 14

Likes: 4

C4 Cooking Issues

Quote:

Originally Posted by Martyspartys

I have a '94 C4 LT-1 6 spd w 38 K I've had it for 6 months and done a few things.
What bothers me is it has always run hot. In summer with out air on the gauge reads 245. I read that with air on both fans run. That is how I've been driving the car. I read that i can wire both fans to one solinoid ? Any ideas?? Thank you

I have similar problems, same car, I replaced both solenoids to no avail. Mine will cool down with the air-conditioning on. One fan will turn on without the AC but the temperature still rises to 245 when stopped in traffic.

I will be interested in hearing from other members.

Dec 22, 2025 | 08:37 AM

#23

Natty C

Melting Slicks

Joined: May 2019

Posts: 3,243

Likes: 1,404

From: Mid-Atlantic

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Just opining here, but I have to say that one of the most annoying, problematic things, pain in the rear end things I had to undo when I picked my C4 up was to undo the mess Bubba made when he wired the fans to run all of the time. Ugh. Don't even like thnking about it. What a mess it was.

He had stuff wired up to the wiper motor and all sorts of other hackery.

I ended up just replacing the entire harness.

And the thing is that it was totally uneccesary. The car didn't even overheat o anything. Guess the previous owner just didnlt like that the gauge read on the higher side. And everybody, for the most part, knows that those dash gauges aren't worth a darn anyway.

Every time I see any mention of rewiring fans I'm like noooo...don't do it....you don't have to.

But...it's someone elses car and I guess they can do what they want with it.

I guess what I'm saying is that if anyone wants to rewire the fans, try to do it as cleanly and reversable as possible.

Dec 23, 2025 | 08:26 AM

#24

llapine

Cruising

Joined: Jul 2024

Posts: 14

Likes: 4

245 using digital readout. Radiator was clogged with degree but after cleaning the situation persisted. BTW, I used a stiff brush tapped to a yard stick to clean the radiator!

Dec 23, 2025 | 09:48 AM

#25

Steve Swan

1994 LT1 1996 LT4

Joined: Sep 2024

Posts: 772

Likes: 730

From: East Front Range Colorado

Quote:

Originally Posted by llapine

245 using digital readout. Radiator was clogged with degree but after cleaning the situation persisted. BTW, I used a stiff brush tapped to a yard stick to clean the radiator!

@llapine The method you employed will not remove debris packed between fins. The debris you see in pics is what compressed air with a long wand blew out. from my 94's radiator Even still, after the blow out, between 1/4 - 1/3 of radiator was so blocked that the sun could not shine through.

Last edited by Steve Swan; Dec 23, 2025 at 08:32 PM.

Dec 23, 2025 | 09:51 AM

#26

pltmgr

Melting Slicks

Joined: Oct 2003

Posts: 2,189

Likes: 830

From: Chapel Hill NC

2025 c3 ('68-'73) of the Year Finalist - Unmodified

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Im with Natty C on this. Had an unmodified 94 that was a DD in the Florida heat for years that never overheated. Currently have a 96 with no problems.

If any wiring modifications are done I suggest labeling as much as you can, This may help you later on and definitely the next guy in line. Over the years, its been a extremely rare occasion that I have found wiring done by POs that wasn't an absolute mess.

Dec 23, 2025 | 02:44 PM

#27

Natty C

Melting Slicks

Joined: May 2019

Posts: 3,243

Likes: 1,404

From: Mid-Atlantic

2025 C4 of the Year Finalist - Unmodified

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If it's the original radiator, I'd replace it regardless just because.

As was mentioned, the DeWits ones are good.

Obviously, make sure you flush nice and good and swap out the thermo.

Condenser gets cruddy, too...

Dec 23, 2025 | 03:09 PM

#28

Cruisinfanatic

Le Mans Master

Joined: Jul 2004

Posts: 6,228

Likes: 698

From: Clifton Park, NY ............Clearwater, FL ... 85 Original Owner

Quote:

Originally Posted by llapine

245 using digital readout. Radiator was clogged with degree but after cleaning the situation persisted. BTW, I used a stiff brush tapped to a yard stick to clean the radiator!

I'm sure you got all that was on the outside, but that does not clean clogged fins