Mark 8 fan install in my sc

davec73

SCCoA Member
I am installing a full size radiator and a mark 8 fan in my sc the question I have for you guys is the mark 8 fan only has a 2 wire plug so I dont guess it has a low setting? I just thought I would ask around and see if you guys think I should run the mark fan on the low setting, high setting or try to swap the fan motr out for an sc motor with the bigger fan and shroud? Will it be possible for me to change the settings in the qtr horse to make the single speed fan kick on high at lower temps without worrying about the low speed because of the increased cooling capacity? All of your input is greatly appreciated !

David
 
Well they can be wired high and low. I have done it.

Then it wasn't a factory Mark fan.

If you'll check http://www.philent.biz/images/1996_Mark_VIII_Cooling_Fan.PDF you'll notice it has THREE terminals, ONE labeled "Not Used". By 1997, they only had two connections.

The ECM does pulse width modulation of the Mark VIII fan to get the variable speed.

There are aftermarket controllers that can do the same, but for that money, putting the 2-speed TBird motor in makes more sense to me.

http://forums.tccoa.com/showthread.php?t=136722 is a VERY good thread on the Mark VIII fan motors out there.

RwP
 
are they dual speed David or what the heck should I do now?

It's single speed fan on all the applications I've seen. It's easy to wire up to the current fan wiring but it's going to pull so many amps at start up if will likely melt the wires and the alternator isn't really big enough either. It would be wired the same as the single speed fan you install when switching to an MP FMIC. SC fan wiring has 3 leads hot high hot low and ground. You tie the high and low speed hot leads together and attach a single 10 gauge power wire to the fan and extend the ground wire with 10 gauge lead. Don't use the Mrk 8 fan connection because it will melt, just use insulated female spade connectionsto attach to the fan motor.

I've got one those fans on my 93 SC and would strongly recommend contacting DCC (Delta Current Control) for a stand alone fan controller that is made specifically for use with that Mrk8 fan. I burnt up the wiring on my first Mrk8 fan using a Lonnie Doll wiring kit that hits it with full voltage and doesn't limit the amps, which is the same thing that will happen if you use the stock SC fan wiring.

The control unit from DCC gradually rolls in the voltage and limits the fan to only pulling 35 amps. Fan speed is controlled by coolant temp using a probe that fits into the fins of the radiator. It hooks straight to the battery and doesn't use your current fan wiring. Since the amp draw is limited it should also work with the stock alternator.

http://www.dccontrol.com/

David
 
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OK it looks like they had 2 different fans in the mark 8. One that was a variable speed fan and one that was a 2 speed fan. I guess I have always gotten lucky and found the 2 speed ones. The link that Ralph posted show how to tell which one is which.
 
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So i take it that the 2 speed fan will work with our ircm and the variable 1 speed wont? The fan I have has the white plug and the serial # is close to the 2 speed one listed in the thread but its not the same. It also has the three terminals but has a blue and white wire only coming from the two outer posts. I guess I could use the controler that is 80 bux from dc controls but I think I have to know if it is a two speed or not. with the short amount of time I have to get ready I may have to have my stock radiator hot tanked and flushed and use my stock setup and get this on after I get back from the shoot out.
 
OK it looks like they had 2 different fans in the mark 8. One that was a variable speed fan and one that was a 2 speed fan. I guess I have always gotten lucky and found the 2 speed ones. The link that Ralph posted show how to tell which one is which.

R1dd1ck913 - Look at that AGAIN.

Genuine factory installed Mark VIII fans were ALWAYS 1-speed.

ALWAYS.

If you got a 2-speed out of a Mark, it wasn't factory.

Yes, it may have had three positions in the connector - 12V, Return, and Not Used. Only two were used.

Speed control was ALWAYS done via PWM off the EEC in the Mark VIII.

RwP
 
So i take it that the 2 speed fan will work with our ircm and the variable 1 speed wont? The fan I have has the white plug and the serial # is close to the 2 speed one listed in the thread but its not the same. It also has the three terminals but has a blue and white wire only coming from the two outer posts. I guess I could use the controler that is 80 bux from dc controls but I think I have to know if it is a two speed or not. with the short amount of time I have to get ready I may have to have my stock radiator hot tanked and flushed and use my stock setup and get this on after I get back from the shoot out.

DaveC73 - Think about it.

"but had a blue and white wire only"

It's a single speed fan. Electric fans are usually (# of speeds = (# of wires - 1) ).

ALL factory Mark VIII fans are single speed.

ALL.

OTOH, as that thread mentions, you can graft a 2-speed TBird/Cougar fan in and use the shroud and blades.

Or get that DC Controls controller. That has the advantage that it'll use any future fan also.

RwP
 
Well I love how every one has to be right. I pulled the fans off the cars in the junk yard my self. I traced the wires from the fan plug myself to get as much wiring as I could so I didn't have to lengthen wires. All 3 wires where hooked up on the mark 8 fan that I pulled my self. And it all was factory wires. I can hook the wires up and get a Hi and Low out put.
 
DaveC73 - Think about it.

"but had a blue and white wire only"

It's a single speed fan. Electric fans are usually (# of speeds = (# of wires - 1) ).

ALL factory Mark VIII fans are single speed.

ALL.

OTOH, as that thread mentions, you can graft a 2-speed TBird/Cougar fan in and use the shroud and blades.

Or get that DC Controls controller. That has the advantage that it'll use any future fan also.

RwP

Ralph I may be mistaken but the TCCOA thread that you posted clearly states that certain years com with a two speed fan? All in all it only matters if both fans can be used with the dc controls controler thats fine. For the fab I am going to have to put into this project For the shootout I will prob have to take my radiator into a shop get it cleaned and run it because I have a new water pump heads and the qtr horse where I can adjust the temps. May re visit this after the shootout is over thanks guys
 
I did see where some one said that the mark 8 fan pulls more power then the sc fan. You could always just use 2 relays for hi and low wired up where the stock wiring kicks the relay on and then kicks the fan on.
 
Dave,

This thread over on TCCoA has a lot of info and pics of the original Mrk8 fan I had and the unit I'm currently using from DCC.

http://forums.tccoa.com/showthread.php?t=116879&highlight=mrk8+fan+wiring

Doesn't look like DCC is offering the fans with controller installed like I got, but they still offer the controller kit that you can install yourself.

I would not reccomend hooking up a Mrk8 fan to the stock wiring, because I don't think it can handle the amp draw at start up. It needs a 75 amp relay and a 100 amp fuse if setting it up to turn on with full voltage, like the stock fan on an SC does.

Spal sells a 3000 cfm extreme duty fan that would work better on an SC radiator that looks similar to the one used with the MP FMIC. I can give you some info on that fan, because that's what I'm using in my 91SC with stock alternator and stock fan controls.

David
 
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Dave,

This thread over on TCCoA has a lot of info and pics of the original Mrk8 fan I had and the unit I'm currently using from DCC.

http://forums.tccoa.com/showthread.php?t=116879&highlight=mrk8+fan+wiring

Doesn't look like DCC is offering the fans with controller installed like I got, but they still offer the controller kit that you can install yourself.

I would not reccomend hooking up a Mrk8 fan to the stock wiring, because I don't think it can handle the amp draw at start up. It needs a 75 amp relay and a 100 amp fuse is setting it up to turn on with full voltage like the stock fan on an SC does.

Spal sells a 3000 cfm extreme duty fan that would work better on an SC radiator that looks similar to the one used with the MP FMIC. I can give you some info on that fan, because that's what I'm using in my 91SC with stock alternator and stock fan controls.

David

Thanks David I think I am just going to go with the stock setup for the cooling system for the shoot out. I still have to completely get the motor together, exhaust re fit for headers, hook up innovate boos/shift Wideband gauges and qtr horse get it running then I have to get the front bumperand hood back from paint lol. I have more to do than I want but this is my first shootout and I dont care how many hours I put in to get it there so thats why I am cutting this corner for now. surely with a completely clean radiator w fan running constant on low speed and 2 1500 cfm pusher fans blowing through the fmic I should be ok.
 
Well I love how every one has to be right. I pulled the fans off the cars in the junk yard my self. I traced the wires from the fan plug myself to get as much wiring as I could so I didn't have to lengthen wires. All 3 wires where hooked up on the mark 8 fan that I pulled my self. And it all was factory wires. I can hook the wires up and get a Hi and Low out put.

*amused*

The schematic shows three wires going to the fan. It also shows only TWO inside the fan.

Again, if it was a dual-speed fan, it wasn't factory.

The WIRING may be three wire. The FAN is two wire.

Again, from the factory.

But eh. Argue all you want. Ford just doesn't know about two-speed fans in the Marks, because they used PWM to control fan speed in the Marks.

RwP
 
*amused*

The schematic shows three wires going to the fan. It also shows only TWO inside the fan.

Again, if it was a dual-speed fan, it wasn't factory.

The WIRING may be three wire. The FAN is two wire.

Again, from the factory.

But eh. Argue all you want. Ford just doesn't know about two-speed fans in the Marks, because they used PWM to control fan speed in the Marks.

RwP

Both my Mrk8 fans (1998 Mrk8 replacment) had 3 terminals on the fan motor, and the wiring harness pigtail I bought new from Ford also had 3 wires, but one of the wires doesn't get connected to anything.

I once tried applying power to the extra terminal on the fan motor and nothing happened. Not sure why they bother putting 3 terminals on, when only 2 are used.

David
 
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