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  1. #1

    Default E-fan install 1991 Suburban

    Well, those of you that have been around GMTC for a while know that I can't keep my tools off my Suburban, and this is no different. I am working on installing an electric fan on my 1991 Chevy Suburban. Why am I doing this? The answer is that the mechanical fan takes up a lot of space and isn't the most efficient at moving air, particularly while idling. It's hot down here, so air not moving over the a/c coils means it's not as cold as it can be, though to be honest the a/c worked pretty well before. The fan of choice for this project is the Lincoln Mark VIII fan. Why the Mark VIII fan? Well, it's fabled as the fan that moves the most air out on the market; claimed CFM is 4000+ but noone can agree exactly how much. Another excellent choice of fan are from Ford Tauruses, and while I have a couple of those fans, the CFM is supposedly not as much, though still high. I scored the fans for just under $20 each. So, let's get installin'!

    So, here's what I'm starting with, a boring 20-year old mechanical fan and insanely huge shroud:

    So, let's try to modernize it some. I took off the upper shroud and there's already a good bit of space freed up:

    Here I've completely removed the fan and shroud. It's so cavernous, I think I can hide in there with the engine. You can also see my triple hose clamp job for my transmission cooler lines:

    Next, I plopped the new fan in the engine compartment to try to get a feel of where I wanted to put it. About center looked good and seemed to cover most of the radiator. I'd say I have 80% coverage by the shroud:

    Looking at what I had to work with, I decided that I could reuse the mounting points for the lower fan shroud to mount the bottom of the fan and I'd fab up new mounts for the top. So, I took some aluminum flat bar and bent up a couple of 90-degree tabs:

    I then put the fan back in the hole, made a couple of measurements, and mounted the tabs to the bottom of the fan:

    I cut off the original factory mounting tabs with a hacksaw since they would not be used to clean up the sides:

    I took some measurements for the top mounts, sketched them up, and bent up a bracket that I would later duplicate for the other side:

    And then installed the fan for the last time:

    So, all the mechanical install is done. Now, I need to decide what I'm doing for the fan control. It is a 2-speed fan, and I can decide to operate it just in one speed, or step it between the 2, but either way, I need to find a fan controller. The alternative is to try to roll my own fan control setup with a temp switch and a constant-duty relay. Any suggestions on what I should do for the electrical?
    Last edited by Crawdaddy; 03-19-2013 at 11:18 AM.

    1991 Chevy Suburban 1/2 ton 2WD w/ chevy SBC 350-3/4 ton drivetrain upgrade w/4.10 gears 200K miles
    2005 Saturn ION-2 Stock 277K miles
    1982 Bronco, 1993 Bronco (sold), 1971 M35A2 Deuce and a Half

    There are 10 kinds of people, those who understand binary, and those who dont...

    Remember kids, the only difference between screwing around and science is writing it down- Adam Savage

  2. #2


    Nice work! You made it look easy. I have seen some other installs that make it look like a pain.

    1995 Silverado 4x4
    6" BDS Suspension Lift-3" Body Lift-Add A Leaf in rear -Trailmaster SSV Shocks-Duel Steering Stabilizer Kit -AirAid Cold air intake-
    4.56 Gears with Detroit Auburn Locker-Pro-Comp Traction Bars with duel shocks-Aluminum Skid Plate Kit-38.5" x 16.5" Mickey Thompson Baja Claws-Constant Dropping fuel gauge

    2005 Yukon XL Jet Power Programmer, Bilstein Shocks, Bilstein rear springs, Helwig Anti-sway bars, EGR Window Visors, EGR Hood Shield, Denali Headlights, Headlight harness upgrade, GE NightHawk Bulbs, White Night Rear lighting system, Russell Braided SS brake lines, PowerStop Brake pads, PowerStop cross drilled and Slotted Rotors,
    2002 Silverado ext cab 2wd (Sold)
    2003 Yukon XL (Totaled)

  3. #3


    That was about 5 hours of work that I spread over 2 weekends. The brackets aren't perfect and pretty because I bent them in a vise with a crescent wrench and hammer, and overall it's not show quality, but nothing on the truck is. I'm happy so long as it works.

    I am considering rolling my own fan controller with a fixed temp switch and a constant-duty relay. However, I'm still up in the air where I'd put the temp switch. Right at the thermostat housing seems to make sense, but I haven't found a water neck with a sender port that will fit the application yet. There's a pipe plug in the passenger head that's used on the drivers head for the engine temp gauge, but I don't know if that would make the fan never turn off because the temp would never get below the trip point. It might work if I used a 210 degree switch, but I'm still unsure. I am VERY much open to suggestions. Electrical is my forte, but this also entails thermo-mechanical engineering too. Collinsperformance has a similar write-up with a Taurus fan on his motorhome, but I can't find it at the moment. It used to be stickied.

    EDIT: it wasn't Tim, it was Collinsperformance. Here's a link to his thread:
    Last edited by Crawdaddy; 03-19-2013 at 11:58 AM.

  4. #4


    what about a t-stat housing for a 1978 chevy motor? I found one with a 1/2 npt port.

  5. #5


    That might just be the ticket for putting a temp switch in. I am concerned that the height/angle of the outlet might put it right in line with the reinforcing bracket for the a/c compressor and belt tensioner. I'm gonna see if my friend can get one for me to check out.

  6. #6


    There are a few different types on that site. I am sure if you google it you may find the correct outlet angle.

  7. #7


    I talked with my friend who works at AutoZone. 814899 is another neck that might work and is cheaper. It actually has 2 ports on it and is in stock whereas the Mr. Gasket one is special order only.

  8. #8


    I picked up the 814899 water neck last night and it looks like it will fit, but now I'm looking for a hose to fit. I might end up using a universal hose and make a couple brackets to route it, but I'd much rather use a factory pre-formed hose. The hose for a 90 Chevy Suburban seems like it might fit, but from the pics it seems like it might go to a passenger-side radiator outlet where I need a drivers-side one. Also, the hose at the engine side has to make a sharp corner upward immediately coming off the water neck. It'll be an interesting puzzle to figure out, but I think I have it.

    I was planning on changing the hoses and thermostat while I was at it anyways since they're original to as long as I've had the truck.

    - - - Updated - - -

    So far, this controller from Derale is looking like the fan controller I will most likely be using: . I will also need to tie that controller to a heavier-duty constant duty relay to feed the hungry needs of the fan. Choosing the relay will take some research or a custom mount made because most heavy relays use the mounting tabs for grounding of the relay and the fan controller output goes to ground to power the fan.

    But for that price, I could get a static temperature switch like this: and probably get the same result.

  9. #9


    Shameless bump to get more ideas. I'm still stuck on the electrical part. At this point, the plan is to get a fixed temp switch and constant duty relay to power the fan. I just can't get over $40 for a temperature switch. Does anyone know where I can get temp switches cheaper?

  10. #10


    Last night I ordered the Derale 16731 switch I mentioned earlier. The bill with shipping was around $35. It should be here hopefully tomorrow and if not then, Monday. Now to find a nice constant duty relay or two...

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