Mark VIII fan install

[85_SS]

After finding out that the Mark VIII fan was too much for the SPAL V3 to handle, I decided to scrap the whole controller idea and make up my own harness/diagrams for a hopefully trouble free system. I designed it so that it operates much like an electric fan in newer cars. It also has a high speed manual override switch, as well as feedback through a single RGB LED for the various states (high/low/AC).


Mark VIII fan installed:

Relays/custom harness wired up and ready to go:

(figured I may as well make use of the Maxi-fuse holder from a painless 70A wiring kit I decided not to use)


Relay rack fits nice and snug next to battery (one more relay was added for proper LED control due to fan motor feedback on opposite speed):

And finally here's the LED in the different stages (mounted at manual override switch/temp gauge):

Off:

Low Speed:

High Speed:

A/C:

It will be nice to finally have a trouble free, fully operational fan setup - beats the unreliability of these worthless controllers out there!

 

[85_SS]

Here's the final schematic and wiring diagram I designed:

 

[DailyDrifter]

Good work, You should put this in the "How To" section.

 

[PaCemkr86]

excellent write up

 

[IawoBill]

Fan Install

I Like It, Very Nice.

 

[Mark E.]

I run this fan on my 94 LT1 in my 65 Olds Vista Cruiser.

I heard about it from my rock crawling habit, but it will be on my GN soon also.

These things just plain rock.......

I have only used low so far.

 

[paintitblack]

I have one of these fans and waiting to wire it up. Do you remember which wire colors are the high, low, and ground?

 

[85_SS]

Thanks guys.

Mark - yes, I've tried a couple other fan setups and wanted to do this one last time so I went with this fan. No other fan out there, stock or aftermarket compares to this thing. They flow nearly 5000cfm on high from what I have read and 2800 or so on low (which is about what most good aftermarket fans flow). Also, for information purposes - I borrowed a clamp-on meter from work and at 12V (car off) high speed pulled around 80A in-rush and 21A running. Low speed pulled 52A in-rush and 12.5A running. These values would be a touch higher with the car running.

I have one of these fans and waiting to wire it up. Do you remember which wire colors are the high, low, and ground?

Some Mark VIII fans are single speed and some are two speed. On the three speed versions, the wires are as follows:

Blue - Low Speed
Black - Ground
Black/Orange - High Speed


...on the single speed versions there are still three wires, but the centre wire is a dummy and does nothing as there are only the two outer wires connected to the motor. I'm not sure of the wire colours on these versions.

 

[turboc87gn]

I may do this to my small block regal subd....

 

[charlief1]

Real good write up and you SHOULD put this in th DIY section.

 

[85_SS]

If a mod can let me know whether I should re-post the thread there, or if it's better just being moved to avoid a double post that would be great

I should note that the actual fan installation requires notching the bottom edge of the shroud about 1/2" or so to get the fan to sit at a nice height with the rad top plate. I bolted two studs to the lower rad support in factory holes, and it is mounted at the top to the rad bracing with another two bolts with allenheads on them. No drilling required in the factory parts (which I'm always very adamant about). On a similar note, the relay bracket is bolted using the two factory bolts in the battery tray on the passenger side.

 

[1BADTT]

85 SS, where can these Mark VIII fans be found? Price? Will they fit a GN with a front mounted intercooler? The pipes won't interfere? Sorry for all the ??s. :redface:

 

[85_SS]

I bought mine off of ebay. I believe it's the pre-97 Mark VIII's that are two speed, whereas the 97/98 models are single speed.

I am not sure how well they may or may not fit with the intercooler on a TR. The dimensions are 22"W x 18.5"H x 6.25"D, but you can cut down the depth an inch if need be. With my SBC, I have about an inch to spare between the fan motor and the waterpump pulley.

 

[87GN_70GS]

Those fit an SS because there is no stock location intercooler. They will probly not fit a GN wtih SLIC.

 

[incharge]

Can this fan be installed so the it comes on automaticlly when the engine reaches temp or do you have to remember to flip a switch ?

 

[jhanson1750]

Based on the schematic and wiring diagram the fan can be operated manually or left alone and it will turn on when the temp probe "closes" the circuit. Jon Hanson

 

[85_SS]

Based on the schematic and wiring diagram the fan can be operated manually or left alone and it will turn on when the temp probe "closes" the circuit. Jon Hanson

Correct - low and high work automatically off of separate temp switches. Both A/C and the manual switch will force it to high speed regardless of any other inputs.

 

[85_SS]

Due to the unexpected operation of the Hayden controller with the engine off, I have made one final change to the diagram so that the fan will only run with the car on.

What was happening is the fans would run for a minute or two when the car turned off (as expected and designed for). I expected this might happen 2-3 times as the coolant would increase in temp again a few times once the fan stopped. This did happen, but the odd part was after a while the controller would call for the fan to be on for a split second every minute or so and this went on basically until the car naturally cooled down. This wasn't good for the battery and left me with just enough juice to crank the car over a couple times. I didn't like the idea of possibly getting stranded with a dead battery, so I made a minor change that only allows the fan to run with the ignition on:

On a side note, regarding how to tell the difference between the 1 and 2 speed Mark VIII fans, I put this quick image together for reference:

 

[RUQWKNF27]

I just put one of these on my 69 camaro and wow! Sounds like a jet turbine in front of the motor! I just wired it to run on hi thru a t-stat switch and also with a manual switch inside!

 

[RUQWKNF27]

I just put one of these on my 69 camaro and wow! Sounds like a jet turbine in front of the motor! I just wired it to run on hi thru a t-stat switch and also with a manual switch inside! Beware of some of the ones on Ebay they sell cause some of those are Ford Taurus fans although still good not as powerful.