Over heating
Thread Starter
Instructor
Joined: Jun 2025
Posts: 139
Likes: 2
Over heating
I have a 1988 C4 5.7 TPI engine swap in a 89 S-10 that has a 2 row radiator with two 10'' electric fans and it seems to run hot when in traffic. I'm going to purchase a new aluminum radiator but I don't know if I should buy a 3 row or a 4 row. The 3 row is considerable cheaper but I don't want to come up short and it still runs hot. As always any advice will be very much appreciated.
Racer
Joined: Sep 2017
Posts: 385
Likes: 93
From: Alaska
This ^^^
If it's running overly warm, I remember reading things to do in the Jaguars That Run, S10 V8 swap book.
I don't recall where I have that book in storage, but the first thing I remember out of it was they listed a specific application that had the largest production radiator that could be made to fit in the S10 core support.
I would take that suggestion from the book and put the largest radiator you can physically fit.
If instead you want to try to figure out how much larger capacity radiator you want, you could loop in a spare heater core with whatever fan you can come up with, and see how much cooler that volume gets you.
I wouldn't recommend putting the auxiliary core in the cab, put it in the fenderwell, under the bed, wherever you find the room.
I generally find the time I save by just cramming the largest radiator I can physically fit is worth (to me) the cost of the greater capacity radiator.
I seem to recall they recommended a shrouded engine driven clutch fan because it moves more air than an electric fan can.
If it's running overly warm, I remember reading things to do in the Jaguars That Run, S10 V8 swap book.
I don't recall where I have that book in storage, but the first thing I remember out of it was they listed a specific application that had the largest production radiator that could be made to fit in the S10 core support.
I would take that suggestion from the book and put the largest radiator you can physically fit.
If instead you want to try to figure out how much larger capacity radiator you want, you could loop in a spare heater core with whatever fan you can come up with, and see how much cooler that volume gets you.
I wouldn't recommend putting the auxiliary core in the cab, put it in the fenderwell, under the bed, wherever you find the room.
I generally find the time I save by just cramming the largest radiator I can physically fit is worth (to me) the cost of the greater capacity radiator.
I seem to recall they recommended a shrouded engine driven clutch fan because it moves more air than an electric fan can.
Last edited by Nexxussian; May 17, 2026 at 01:52 PM. Reason: spllng
Melting Slicks
Joined: Nov 2016
Posts: 2,256
Likes: 3,084
From: So Cal
2023 C4 of the Year Finalist - Unmodified
So. I guess you have it running and starting now? There are 112 posts in those two threads. The peeps that participated would be interested in knowing what the final resolutions were.
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You didn't specify, but if it stays cool when moving, but heats up when not moving, that's airflow.
(2) 10" fans is 157 in sq of surface area. I'm guessing that a stock C4 single fan is 16" diameter, so 200 sq inches of surface area are covered in a stock 84-89 C4. You have roughly 25% less fan surface area than a stock 84-89 C4.
A stock C4 radiator has about 390 in sq of surface area. I'd also guess that because your fans are pushers, they are not mounted in a shroud where the fans will flow through the entire surface of the radiator, rather than just the area of the fans. The stock C4 fan shrouds pull air through the entire surface area of the radiator. Not just the area of the fan(s) alone.
If it stays cool when moving, but not when "in traffic" you have an inadequate airflow problem at low speeds. Not a radiator problem.Think about it.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
You didn't specify, but if it stays cool when moving, but heats up when not moving, that's airflow.
(2) 10" fans is 157 in sq of surface area. I'm guessing that a stock C4 single fan is 16" diameter, so 200 sq inches of surface area are covered in a stock 84-89 C4. You have roughly 25% less fan surface area than a stock 84-89 C4.
A stock C4 radiator has about 390 in sq of surface area. I'd also guess that because your fans are pushers, they are not mounted in a shroud where the fans will flow through the entire surface of the radiator, rather than just the area of the fans. The stock C4 fan shrouds pull air through the entire surface area of the radiator. Not just the area of the fan(s) alone.
If it stays cool when moving, but not when "in traffic" you have an inadequate airflow problem at low speeds. Not a radiator problem.Think about it.
Last edited by IHBD; May 17, 2026 at 03:58 PM.
Melting Slicks
Joined: Nov 2016
Posts: 2,256
Likes: 3,084
From: So Cal
2023 C4 of the Year Finalist - Unmodified
The take-away is to use the largest cross-flow mono-tube radiator as it is possible to fit in the application. The OP asked about 3-row vs 4-row. The C4 (and S-10) radiator(s) are mono-tube. The standard cooling version is a 1" thick core. The HD versions are a 1-1/2" thick core. Both mono-tube designs. A mono-tube design has more surface area exposed to the coolant flow than the equivalent thickness core with multiple "rows".
Thread Starter
Instructor
Joined: Jun 2025
Posts: 139
Likes: 2
I'm sorry that I didn't post the fix on Corvette forum. I had switch to Third Generation F-Body fourm and that's where I posted the fix. I will post it on this forum as well. Lets start over on the coolent problem. Instead of changing the radiator what could I do to fix the flow problem. I'm limided in space and cannot get a fan between the engine and radiator. by the way your are talking above my head with the types of radiators
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