Engine Fan Opinion

[69BlazBlaz]

I have a '69 blazer that the PO installed electric fans on with a SBC 350. They were wired with a switch on the dash that you have to turn on for them to work. After sitting for a little while now, I have to move it and found the fans have power but are not working. I want to put a mechanical fan back on it. What is a good brand fan and maybe fan clutch to install? Don't mind spending a little money for good quality, but like always, don't want to spend and arm and a leg for a fan.

[hemi43]

Don't put a mechanical fan on. Electric is the way to go, but the most important thing is to have a proper shroud. Flex-A-Lite makes excellent electric fan/shroud combos. I've used a few in the past with excellent results. They come with a temperature probe that senses fin temp, but don't use it. The best way to control a fan is with it's own separate thermocouple located right in the water jacket. There should be a location on your intake for you to install this thermocouple. Size your shroud so that it covers 100% of you rad, and you will never have an overheat issue.

Get this style VVVVV


NOT this style VVVVV

[69BlazBlaz]

That second picture is what is on there now. Does the thermocouple come with the fans you recommended or is that a separate part? Other than a small HP loss, what’s the advantage over a mechanical fan? If the fan stops working, like mine has, is there a safety on it to let me know so I don’t overheat? I know I should be watching the temp gauge, but I don’t constantly watch it everywhere I go. Just questions I have.

[hemi43]

Originally Posted by 69BlazBlaz

That second picture is what is on there now. Does the thermocouple come with the fans you recommended or is that a separate part? Other than a small HP loss, what’s the advantage over a mechanical fan? If the fan stops working, like mine has, is there a safety on it to let me know so I don’t overheat? I know I should be watching the temp gauge, but I don’t constantly watch it everywhere I go. Just questions I have.

An electric fan is more efficient, especially if driving slow or idling. Mechanical fans were never any good even brand new, and I blame the fan shape design as well as the large gap needed between the fan blade tips and the shroud. This gap is to allow the engine to flex under load and not have the blades hit the edge of the shroud.
Most of the installs I do are on computer controlled vehicles, so it's easy to switch the fan on and off because the vehicle's computer has one or two fan outputs that can easily be programmed. The link below is a simple type of controller you want if you don't have a computer controlled engine. I've never used this particular one, but it's one I quickly found doing a search. As I said before, it senses coolant temperature, not fin temperature.

https://www.summitracing.com/int/par...85fh/overview/

[1rippen6]

If you are looking for an original fan I have on off a 72 blazer.

[RustyBucket]

Originally Posted by hemi43

Mechanical fans were never any good even brand new
[/IMG]

different OPINION .... have 7 blade clutch fans w/shrouds on both of my old trucks, both have A/C, 1 SB, 1 BB w/headers. Plenty HOT in central Florida. Both trucks run cool and quiet in traffic or waiting on my wife shopping. My DD '02 GMC 6.0 and wife's '06 GMC Savanna 5.3 have factory mechanical fans too. I think the fan blade and clutch are available from auto parts chain stores... Advance, O'rielly..... LMC or one of the repro. suppliers have the shroud OR maybe find an original. I'd get the shroud first and buy the appropriate diameter blade.

[simicrintz]

Lots of guys like the switch on the dash to manually turn the fan(s) on or off. The guys in my Jeepster page shut them off when doing water crossings, for example.

[Haggar]

For the electric option, the dual electric fan from a Ford Windstar is very popular. I don't have the part number anymore, but late 90s. I think there are two sets of years, both work, I think. Googling around should get you the part numbers.

I am running one of these with a 3 relay setup that I found on this forum. I got mine new on Amazon for less than $100. We recently did 3 hours of Woodward cruise, street temp was over 100 degrees, and it was mostly dead stopped. Engine never got over 190 degrees all day, and I have never seen the fans engage high speed yet. This is with a built 6.0 LQ4 with headers that do heat up the engine bay. Was pretty easy to adapt the shroud to seal up pretty well to the rad and core support

[Haggar]

https://ls1tech.com/forums/conversio...tric-fans.html

[viking427]

If you go with an oem viscous coupled ("clutched") mechanical fan, get the matching shroud also. The fan blade tips should protrude 1/2 in and 1/2 out of the shroud. I agree the better electric fans are more efficient, but I've never had a set last more than a few years without some sort of problems (seizing up, relays, controllers etc.). where my oem clutched mechanical fans seem to last decades trouble free.