Fan upgrade


Active Member
I recently put on a cold air intake and got pcm of nc tune. I'm seeing available upgrades for fan. What's the difference between and all electric like pcm and a thermo setup. Is the that no different than what we got stock? What's the unbalanced cooling system we have? Any articles on the topic? I did use the little magnifier thingy at the top but didn't find much.


If you're referring to the electro viscous fan clutch that most of us have, versus the thermal fan clutch, it's not really recommended to make that change until your current clutch fails. There's no performance improvement, just a bit more reliable against failure.

If you're talking about removing the clutch driven fan setup completely, and switching to e-fans, the problem is our radiators are small (thin) and electric fans simply don't pull enough air to compensate for it. GM put in a huge clutch driven fan to balance out the radiator size. A number of us have tried different setups with efans, and they simply did not cool the system well enough, so we went back to clutch driven systems.
All of these trucks came stock with an engine driven fan clutch. 02-07 used an electro-viscous fan clutch and 08-09 used a regular thermal fan clutch. There are a few people here that tried electric fans and switched back because the e-fans can't move enough air to keep the temperature down at all times, especially with the A/C turned on. The cooling system is unbalanced because the radiator is relatively small, so the fan needs to move large amounts of air to compensate.


Active Member
Got ya. Thank you for the explanation. I bought this used and I seem to remember seeing some paperwork about clutch replacement from previous owner. Of course the dealer threw all that away when detailing. Said it was private info about seller. Is there a visual indicator I could look for to see if it was replaced?
The EV fan clutches are slightly larger than the thermal ones and they also have a wiring harness that clips onto the right side of the fan shroud. The brand on my factory EV fan clutch was Behr. The EV fan clutches are a bit unreliable, so many of us replace them with the 08-09 thermal clutch when they fail like Blckshdw said and delete the fan code with a tune.


Yeah, even GM saw its weaknesses and switched to thermal in 08. However, if yours is running fine, wait till it fails to switch.


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Hijacking this thread, since we're talking about unbalanced cooling... is there an upgrade option for the radiator, short of a full custom piece?

Always, the talk is about the fan clutch, so I'm guessing 'not'.
There's an FSR radiator for the TBSS that should fit the 5.3 but every aftermarket radiator for the 4.2 seems to be identical to the stock one. The only difference seems to be that the lower hose connection is on the passenger side on the V8s.


There is another one, kind of. Someone used a Dodge big block aluminum radiator with their efan setup. These seem to be the ones with the same (or near same) dimensions and hose placements for the 4.2. V8 has different hose placements, especially the lower hose.



The upgraded radiator can be found on the ORTB site, but even combining it with the E-fans was found to not be enough for proper cooling.

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