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Getting hot at highway speeds -Solved?

There are a few different fan setups.

But when talking clutched fans, there are multiple blades (7 or 9 being max I want to say) and there are apparently light and heavy duty fan clutches.

Someone might have info on how the two fan clutches are different. HD is supposed to cool better.

TBI ran that reverse rotation fan setup, but I dont see how that would affect cooling as long as the fan is turning the proper direction.

I've heard multiple times that when taxed with high ambient temps, GM AC of this vintage isnt spectacular. But if idle RPM is low, then bumping that up a hair may help. Have you tried to use the throttle to push idle RPM up and see if AC gets better?

This is one reason electric fans can be better. Their RPM, and thus most efficient operation, is not dependent on engine RPM.
 
I haven’t messed with the engine RPM (yet). I made sure that it was set to the book when I initially set the thing up.

I’ve been doing a lot of reading on different sites regarding the radiator. The aluminum 4 core I put in at the beginning is 2 1/2” thick core which means the 4 cores are pretty small. I couldn’t find the specific size of the core passages. Would a 2 core with 1” or 1+” flow be better? I’m seeing those being run with a lot of success.
 
I was having same shitty cooling issues but with a shitty dual fan that was maybe 2000 cfm. The Flex-A-Lite 295 fixed my over heating issue but I'm at cooler temps here in Denver. My radiator is also a cheap alum. 4 core. Its not built the greatest. If I had to do radiators again, I'd buy the big diesel radiator which is even wider and run the wider Flex-A-Lite 6000 cfm fan. The 295 is 4600 and seals well against the core. I didn't like the Windstar since after you cut it to fit, there is huge gaps on the sides and its less CFM than the 295. That makes a huge difference.
 
Shawn said:
I was having same shitty cooling issues but with a shitty dual fan that was maybe 2000 cfm. The Flex-A-Lite 295 fixed my over heating issue but I'm at cooler temps here in Denver. My radiator is also a cheap alum. 4 core. Its not built the greatest. If I had to do radiators again, I'd buy the big diesel radiator which is even wider and run the wider Flex-A-Lite 6000 cfm fan. The 295 is 4600 and seals well against the core. I didn't like the Windstar since after you cut it to fit, there is huge gaps on the sides and its less CFM than the 295. That makes a huge difference.
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You just completely summed up my entire build with the fans and radiator. I returned the 295 and I still have the Windstar fans in my garage.
 
AZ79K5Project said:
I haven’t messed with the engine RPM (yet). I made sure that it was set to the book when I initially set the thing up.

I’ve been doing a lot of reading on different sites regarding the radiator. The aluminum 4 core I put in at the beginning is 2 1/2” thick core which means the 4 cores are pretty small. I couldn’t find the specific size of the core passages. Would a 2 core with 1” or 1+” flow be better? I’m seeing those being run with a lot of success.
Click to expand...
Mine is an elcheapo aluminum with plastic tanks. It said 2 core/row. But the water passages are about an 1" wide each and it does wonderful. No matter if I'm on the highway, idling, cruising town, etc, it's 185 always. 94* actual temp is the hottest day I've run it though.

Stock fan/clutch, shroud.
.040 over 454 w/mild-medium cam.
 
I think at least one reason for going with wider but fewer tubes is that it allows air to flow better, and probably more surface area exposed to airflow with less space wasted. Also holds marginally more coolant, and flows better.

I noticed Griffin is making radiators with up to 1.5" wide tubes, so there has to be benefit.

I too have one of the parts store cheapie AL/plastics and it's cooled fine, after replacing an old plugged up copper/brass 4 core that couldn't keep it cool in 90* weather under load. Of course, I'm running a pretty mild setup that minimally taxes a cooling system, so mine isnt a good example probably.

Now if they are making the old giant diesel radiators in AL/plastic, one would be a worthy experiment. I still think the non-OEM AL/plastic are garbage (first one failed as soon as the engine came up to temp in the driveway after install) but with the lifetime warranty nearly nationwide and like $80, it's hard to justify a $500 premium radiator that others complain about failures with.
 
This is the one I bought, and what I wrote about installation at the time.

Screenshot_20200728-091435.png

IMG_20191016_153349435.jpg

Screenshot_20200728-091333.png
 
Yes, that appears to be much thicker than a "stock" replacement k5 radiator.

Doesnt look like the ~34" wide diesel radiators are being made in plastic/AL. At least based on what autozone shows.
 
dyeager535 said:
Yes, that appears to be much thicker than a "stock" replacement k5 radiator.

Doesnt look like the ~34" wide diesel radiators are being made in plastic/AL. At least based on what autozone shows.
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Actually I just bought one.
Autozone has it, o'Reilly has it, napa, Amazon and rock auto which is where I ended up buying, but I have no choice I am running the diesel and I need the engine oil cooler which this one has.
I will report on the quality once I receive it, it's been sitting in Carson, California for a week no idea what is going on.
 
imiceman44 said:
Actually I just bought one.
Autozone has it, o'Reilly has it, napa, Amazon and rock auto which is where I ended up buying, but I have no choice I am running the diesel and I need the engine oil cooler which this one has.
I will report on the quality once I receive it, it's been sitting in Carson, California for a week no idea what is going on.
Click to expand...

Interesting. 1988 r20 suburban 6.2l shows me this 34" radiator, https://www.autozone.com/cooling-he...iator/duralast-radiator-b850/155741_1093051_0 which based on the pic, is definitely not AL/plastic.

What part number or vehicle did you find it under? I see the plastic/AL shown on rockauto, but out of stock. Heck the all aluminum one isnt that pricey, comparatively.
 
dyeager535 said:
Interesting. 1988 r20 suburban 6.2l shows me this 34" radiator, https://www.autozone.com/cooling-he...iator/duralast-radiator-b850/155741_1093051_0 which based on the pic, is definitely not AL/plastic.

What part number or vehicle did you find it under? I see the plastic/AL shown on rockauto, but out of stock. Heck the all aluminum one isnt that pricey, comparatively.
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I called them and they said aluminum and plastic.
850 is the diesel radiator.
Cu850
B850
S850
...
Each manufacturer has a different prefix.
Amazon has 2 brands, one is all aluminum fully welded stamped tanks, looks like good construction but at $297 it was $50 more than the rock auto with shipping.
 
Looks to be only 2 core? Is that the wider width. Thought I saw some 3 cores on the wider radiator
 
Shawn said:
Looks to be only 2 core? Is that the wider width. Thought I saw some 3 cores on the wider radiator
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I did some more searching and I found some 3 row from $150 - 250 range, I wouldn't pay that much for this one.
I paid $245 plus tax for my diesel radiator.
 
imiceman44 said:
Same one on Amazon for $334
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Thanks - I saw that too. The only thing was a week to three week shipping. Amazon lately has been rough with their orders. For the price difference, I don’t want to be down for two or three more weeks.

Shawn said:
Looks to be only 2 core? Is that the wider width. Thought I saw some 3 cores on the wider radiator
Click to expand...
It’s a two core rated pretty good and 1” cross tubes. It’s a 3” radiator which is thicker than my current 4 core.

imiceman44 said:
I did some more searching and I found some 3 row from $150 - 250 range, I wouldn't pay that much for this one.
I paid $245 plus tax for my diesel radiator.
Click to expand...

Does the diesel one have the plastic tanks? I’m a little concerned with that since we are looking at 115 today for a high temp. My junk is parked outside year round. Did you have to make any modifications to make it fit? Hoses, etc?
 
20200722_193551.jpg I chose a Cold Case direct fit for my 66 Fury. Just installed it this past weekend and the car doesn't run yet. Looks great as far as build quality goes. I gladly paid a little more for something that wasn't chinesium.
 
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