Mark VIII Fan Two Speed or Not?

[SamHatco]

The debate on the Mark VIII fan being a two speed fan has been argued many times here, but there have been no pictures to show us which one is the true two speed fan or a single speed fan. I thought I post some pictures of my fan and let the experts tell me what I have. Maybe this will be useful when guys are checking ebay or wrecking yards for their fan so they can tell the difference.











I posted this over in Electrical & Wiring and thought maybe this would be the appropriate place for this question. Can anybody tell from these pictures if this is a single speed or two speed fan?

Sam

[85_SS]

Hi Sam,

The pics you have posted are identical to my two speed fan. The wiring is identical, and the motor does not have the plastic "inspection cover" that seems to only be on single speed fans. I am confident that your fan is a two speed version - if you could do a quick test touching the leads to a battery to confirm that would be great. Black/orange is high, Blue is low and black is ground.

Here's a picture of a single speed Mark VIII fan for comparison (note the inspection cover right next to the plug - if you remove this you will see the centre pin is jumpered to another pin):


I believe the single speed fans were in 97/98 when the Mark VIII went to a factory VSC for the fan. FWIW, the single speed fan I have does seem to pull a fair amount more air than my two speed fan on high - this is consistent with what I have read online.

Hopefully this will solve the confusion once and for all!

[camcojb]

I've always thought the low speed was controlled by reduced voltage to the fan, in the stock Lincoln application. I do know I've had several of them, they all had two power wires and one ground; putting 12 volts to either power wire got the same speed and airflow, leading me to believe the factory used something to lower the voltage to one of the two power wires to create a low speed.

Jody

[85_SS]

I've always thought the low speed was controlled by reduced voltage to the fan, in the stock Lincoln application. I do know I've had several of them, they all had two power wires and one ground; putting 12 volts to either power wire got the same speed and airflow, leading me to believe the factory used something to lower the voltage to one of the two power wires to create a low speed.

Jody

You've only had single speed fans then, and yes, the later model Mark VIII's used a variable speed controller (pwm though, not just changing voltage) to operate the fan. The older two speed fans will indeed run at different speeds when the blue or black/orange wire is energized.

I assume the reason Ford still used 3 wires on the newer fans was so that the new single speed fan could be used for a replacement on all cars. This isn't the greatest idea as the low speed wire is a smaller gauge, but it will work, it's just that the fan will be on high regardless of whether the switches are calling for high or low on the older models.

[SamHatco]

THANKS! GUYS!! I never could figure out which fan I had with the descriptions in the other threads. You know as they say, "a picture is worth a thousand words". I hope this helps other guys looking to get a Mark VIII fan.

Regards,

Sam

[ProTouring442]

Mine is definitely 2 speed.

Shiny Side Up!
Bill

[85_SS]

I put this quick image together using both mine and Sams pics for reference:

[Motown 454]

Is either of them a better choice than the other?

[85_SS]

Just depends what you want. If you don't care about having two speeds, then either fan will be fine.

The single speed fan pulls more air, but the two speed will cool anything IMHO. The Mark VIII fan pulls more on low speed than just about any other stock or aftermarket fan (single or dual) out there.

I wanted both speeds as it will be rare (if ever) that high is required so why draw more current than necessary (I do use high for A/C though). Some will suggest going with a controller to keep the current down, but I've been there done that with both DC Controls and SPAL and have nothing good to say about them - this is why I finally made my own harness so I can be done and not worry about some silly controller dying on me.

[Y-TRY]

Speaking of.. how are you guys mounting your Mark VIIIs? Do you have any bracket suggestions? How about pigtails?

[85_SS]

I have two allen head bolts on the top that mount to the brace on the top of the rad, and I made two studs bolted to the lower rad support that poke through the shroud and are mounted with a nut on each. You can see the upper mount locations and one of the lower bolts in this pic:



In a g-body, you will have to notch the lower shroud to sit lower on the rad support.

[ProTouring442]

I hacked mine up and made a shroud.



Shiny Side Up!
Bill