Gets hot after adding shroud?

L31MaxExpress said:

Yea what was wrong is the electric fans do not move near the CFM of the clutch fan. My clutch fan cools better everywhere including at idle than the Tahoe fans. I had 13.8 volts on the system and 13.5 volts across the fans back probing them on high speed. Problem was purely the fans in my case. Clutch fan moves way more airflow even at idle. It will stick a shop rag to the grille over a foot away at idle. At 2,000-3,000 rpm the clutch fan moves in excess of 10,000 cfm, something the electrics cannot do. My cooling issue was never at idle, it was always climbing a long grade at speed or pulling uphill at slower speeds or in bumper to bumper traffic with constant stop and go. My 8.1L Tahoe has a clutch fan on it too and you could kick back and take a nap in the ice cold ac while the engine sits at 185°F.

My uncle towed his travel trailer into Colorado this summer with a bone stock 2017 6.2L Denali 4x4 crew cab. It went into reduced power mode and shut the ac off numerous times on the grades. Its about to get a clutch fan on it.

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BeXtreme said:

Just a final note on this conversation. I did the math yesterday, and heres what I came up with. A 454 radiator has a 34"x19" radiator. That is ~4.48 square feet of surface area. At 65mph, the air is stationary and the truck is moving at 5,720 feet per minute. That works out to 25,660 cubic feet per minute of air being forced through the radiator at 65mph. I have seen some posts by people with the newer trucks and electric fans, where the rubber pads on the side of the radiator that keep the front sealed on either side of the radiator had torn. This allowed the air an easy path around the radiator and kept it from being forced through the radiator at speed, which then caused it to start overheating. Replacing those side pieces fixed their issues. I was having similar issues for a while and replacing mine also fixed it.

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L31MaxExpress said:

I finished that retrofit actually Friday afternoon. Van stays 185F now on the dot. Its controlled off fan 2 output on the LS PCM, via a relay. The 6.0 LS2 powered the SS and that is what my Hayden was built to replace. Its a severe duty and turns about 50-60% when it is commanded off and about 80-90% when it is on.

A guy on the Express/Savanna group I follow put one on from a 6.6L Van on a 6.5L van. I mounted mine the same way. My van has a newer 3 wire pressure sensor on it. When the ac pressure exceeds Fan 2 setting right after startup the clutch fully engages 5-6 seconds after. Once I am driving around for a few minutes and the interior cools down the pressure drops and the fan clutch releases. The 16" electric puller and the freewheeling clutch have been enough to keep the ac ice cold and the engine at 185F on the dot.

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Markmartin01 said:

So I have a 91, 350, pretty run of the mill truck. Converted to 16" electric fan a couple of years ago after the water pump mount sheared and about threw the mechanical fan through my face. Cooled fine at speed without a shroud, wants to get hot after driving on the freeway and pulling off. Thought it was the lack of shroud so I made one from thin gauge. Made it 5 miles with the shroud and it's getting hot. Fan seems to move a ton of air. But why would adding a shroud make it get hot at slower city speed where it didn't without a shroud at all? Thoughts?

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