Tuning for e-fan conversion?

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L31MaxExpress

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How many failures have you seen? My point is that efans are quite reliable. A lack of reliability shouldn't scare one away from them, the risk is minimal.
I have had several fail over the years. One motor on my Tahoe fans quit after a year and it was a 10K mile assembly. The fans literally ran on high speed all the time when it was over 85°F outside and under 50 mph. I have also seen numerous relays fail on non-stock type setups. GM uses 3 relays on their setup to cushion amp draw on startup.
 

L31MaxExpress

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Based on your complaint of the fan being engaged long-term when cold, you're about to change the wrong part.

You most likely need a new fan clutch, not a new fan. And not an electric fan conversion.

Perhaps $65. O'Reillys lists two Murray clutches, one for '96 Tahoe with A/C and HD Towing Package, another a few dollars less for vehicles without A/C. I admit being surprised that they're suggesting a "severe duty" clutch at all. I was wrong in my earlier post.

There's also the AC-Delco fan clutch, which in the very poor photo appears to be the exact same thing as the Severe-duty Murray in a different box, at triple the price.

Four bolts fan-to-clutch, one bigass nut holding the clutch to the water pump. (36mm on my Trailblazer, maybe the same, maybe different on your Tahoe. O'Reillys loans the special tool set for fan clutches at no end cost--you "buy" it, when you return it they refund your money.

Maybe you also have to pull the rad shroud or something like that...but I suspect not.

Not really the wrong part. Fan clutches are somewhat of a viscous coupling. More blades load the coupling more, slowing the speed of the fan when the clutch is not fully engaged. My 5 bladed sounded like an airplane all the time. My 11 blade was virtually silent by comparison and my Duramax fan would only make noise for the first 1/8 mile or so and then was silent unless I was in stop and go or towing on a ~100°F day. When the Duramax fan would engage my a/c temps at the vents would drop below freezing and actually cycle the compressor off. Even at idle the Duramax fan pulled as much air as electric setups. I will also say that my water pump and at the time fan are 33% underdriven compared to stock with the March pulley set.

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Schurkey

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Fan clutches are somewhat of a viscous coupling. More blades load the coupling more, slowing the speed of the fan when the clutch is not fully engaged.
They are absolutely a viscous coupling. Yes, more blades, or blades with a higher pitch load the coupling more, slowing fan speed. Whether this moves less air is debatable; and I have no idea how this affects noise.

What I don't understand is why his truck requires a "Severe Duty" clutch. I wonder if the description on the O'Reillys web pages is wrong. I get that "HD Towing Package" probably gets a bigger fan, bigger radiator, maybe. Maybe a different pulley ratio on the water pump. Who knows? A HD or Severe Duty clutch isn't out-of-the-question. But a more ordinary vehicle with AC but no "HD Towing" needing a Severe Duty clutch to drive a what is probably a base-model fan? I don't get it. A "Severe Duty" clutch has less slippage than a "Heavy Duty" clutch, which has less slippage than the ordinary thermal clutches. (Non-Thermal clutches are junk and shouldn't be considered.)

My point is, he's maybe got a 5-blade fan just like the one on my K1500, he's got severe fan noise when cold, and I don't. His clutch must be locked-up (faulty) when cold, because they're NOT SUPPOSED TO DO THAT. MAYBE it releases as it warms up, maybe is locked 24/7/365 and he doesn't notice it after awhile. I dunno. When the fan clutch locked-up on my Nova, it was so friggin' loud at highway speed that you couldn't hear yourself think.

My 5 bladed sounded like an airplane all the time. My 11 blade was virtually silent by comparison
Some of that may be due to blade design. The molded-plastic fan blades seem to be more sophisticated in terms of shape than the stamped-metal ones.

and my Duramax fan would only make noise for the first 1/8 mile or so
I'm surprised it took that long to quiet down.

When the Duramax fan would engage my a/c temps at the vents would drop below freezing and actually cycle the compressor off. Even at idle the Duramax fan pulled as much air as electric setups. I will also say that my water pump and at the time fan are 33% underdriven compared to stock with the March pulley set.
Nice!
 

El Tigre

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While mechanical fans themselves are reliable. The load placed over the nose of the water pump do not add reliability to the water pump. I love my dual electric frim Flex-a-Lite it seldom runs at all unless using the A/C . Not a fan (no pun intended) of probes stuck in the radiator. Dakota Digital makes a very nice programmable fan controller with a dedicated sensor I installed in the unused port on passenger side cylinder head.
 

Erik the Awful

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How many failures have you seen?

In the early '90s my parents had a minivan that the fan relay stuck and didn't turn the fan on. It smoked the head gaskets and warped the heads. That was a $1000+ repair bill while we were on vacation.

My son's first Crown Vic burned up the wiring to the fan. The later fans had larger gauge wiring.

I installed a set of junkyard Audi fans on my truck. I bench tested them. Then after installation I verified they worked. A week later they failed, but I immediately spotted the rise in temperature on the Sniper handheld. I threw the clutch fan back on.

I replaced a few electric fans when I was a dealership technician.

The only clutch fan I've had fail was on my RX-7, and it was a rare free-wheel failure. I caught it quickly, but it hurt the motor. In that case I replaced it with an electric fan because I wanted the extra horsepower.
 

El Tigre

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Mechanical fans are clearly on their way out.
How many vehicles have them anymore? Precious few ,mostly tow vehicles....
 

El Tigre

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If you don't want the advantages offered by electric fans?
That's fine ,but let's not pretend they don't exist. My '98 C/K
came with a mechanical fan ,but it's airflow pales in comparison to
the dual-electric fans with built in shroud directly against radiator core.
A/C performance is noticeably improved. Fans are seldom triggered by
coolant temps when truck is moving. When triggered , one fan bring temps down
quickly then shuts off. Compared to mechanical fan ,and it's mediocre air flow that
must always operate to be effective. Mooching between 10-15hp. right off the top....
 

Supercharged111

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If you don't want the advantages offered by electric fans?
That's fine ,but let's not pretend they don't exist. My '98 C/K
came with a mechanical fan ,but it's airflow pales in comparison to
the dual-electric fans with built in shroud directly against radiator core.
A/C performance is noticeably improved. Fans are seldom triggered by
coolant temps when truck is moving. When triggered , one fan bring temps down
quickly then shuts off. Compared to mechanical fan ,and it's mediocre air flow that
must always operate to be effective. Mooching between 10-15hp. right off the top....

At an idle, efans are the bees knees. WOT in 2nd up a long hill in 100+ degree heat lugging a trailer up a mountain pass? Mechanical all the way. There is absolutely no comparison. So I keep electric in the 1500 and mechanical in the dually.
 
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