Mark VIII, installed.

Rerun · Aug 11, 2004

Welp, took all day but I finally got it in and I'm pretty happy with it. Sure is a tight fit though, probably about 2 inches between the fan motor and the waterpump pully. Got it hooked up to a thermostat via a relay with a toggle override. I'm tired, I'll probably take pics tommorrow or something. I used the hot from the cigarette lighter, I'm probably gonna update the 20 amp fuse because I blew it ****ing around. Would hate to not have control of it because the fuse blows out. Probably put a 40amp fuse in there. Thanks for the help HISSIN.

dvs bullet · Aug 11, 2004

It would be nice to see the pics, when you get them. I'm looking at upgrading my fan to that one

Gearbanger 101 · Aug 11, 2004

Rerun said:
Engine
302 5.0 HO / Ported, Polished, Bored Heads / Cobra Intake, upper and lower / MAC Pullies / 70 MM BBK Throttle Body / Roller Rockers / Roller Cam / MAC Cold Air Kit

Hey Rerun.....not trying to be a smart ass, but what exactly is a "Bored Head"? Are you meaning to say "Milled" or "Shaved".....or were you meaning to say refer to the block and not the head at all?

Rerun · Aug 11, 2004

Gearbanger 101 said:
Hey Rerun.....not trying to be a smart ass, but what exactly is a "Bored Head"? Are you meaning to say "Milled" or "Shaved".....or were you meaning to say refer to the block and not the head at all?

No offence taken, I did that in 5 minutes never really actually paid attention to it, but yeah, milled.

HISSIN50 · Aug 12, 2004

Rerun, nice work - glad it went in w/o too many hitches.

a typical 30 amp SPDT bosch style relay coil will draw about 0.3 amps. the HD relays used for mark 8 fans (~20-30 bucks, IIRC - but highly recommended. i think you got one) might draw a smidge more to energize the coil. i cant recall if the cig lighter is hot at all times (some of my cars it is and some not). if it is ignition-key-on hot only, the blower motor fuse might be a choice if you keep blowing fuses (although on the 20 amp cigar lighter/horn fuse, im not sure why you would blow them - it is stout). i think you said you were just messing around.
you can get a CB (circuit breaker) for that fuse (or for your fan or both). i ve used CB's on my bikes and they can be nice as they reset automatically when the circuit cools off. 5-6 bucks at parts store. as you know, dont toss bigger fuses in if you are blowing one. (i say this in case you do blow fuses).

anyhow, great work and im glad to hear you like it. BTW, you think you had a tight fit - Chris (Blackfox) runs a mark 8 fan with a blower! that is a tight fit.

Michael Yount · Aug 12, 2004

If you're pulling your main power for the fan relay from the cigarette lighter circuit, you're probably in for trouble. The MkVIII pulls BIG current - I've seen references as high as 53A; and at startup for a fraction of a second, it will peak at 2 to 3 times that. I suspect you'll need a REALLY stout relay and even more than a 40A fuse to keep it alive.

Here's the ticket - no temp switch/relay set up even comes close to working as well or as efficiently as this does: www.dccontrol.com.

T_5.0_N'works · Aug 12, 2004

Got the fan and Summit radiator at home, waiting on my DCCCONTROL to come in. Can't wait.

Rerun · Aug 12, 2004

Sup fellas, yeah I might take it off the cigarette lighter and use the hot lead from the stereo or something. I followed the following diagram made by one of our own (FiveOhhStang)!

I know it's for a taurus fan installation but I followed the same premise and put a thermostat on it. I'll take pictures today.

iwashmycar · Aug 12, 2004

Michael Yount said:
If you're pulling your main power for the fan relay from the cigarette lighter circuit, you're probably in for trouble. The MkVIII pulls BIG current - I've seen references as high as 53A; and at startup for a fraction of a second, it will peak at 2 to 3 times that. I suspect you'll need a REALLY stout relay and even more than a 40A fuse to keep it alive.

Here's the ticket - no temp switch/relay set up even comes close to working as well or as efficiently as this does: www.dccontrol.com.

From his diagram, it looks like the power is from the battery, and the relay power is from the cig. lighter, so it should be okay.

Rerun · Aug 12, 2004

Jesus H. Christ that fan sucks a lot of energy, I could never just leave it running I don't think, It was just eating my battery. I also found something strange and maybe you guys can shed some light on it. After watching it eat energy I busted out my voltmeter to do some testing. After driving around, with the car off the voltage at the battary post was 13+, what the hell I say! With the car on, the voltage came up a little bit to like 13.64 or around there. The only thing I could think of is that, when I upgraded the wiring on my alternator it has a 200 AMP circuit breaker inbetween the battery and the alternator to protect the electrical system. I also have the battery to relay wired to the same circuit breaker, this is used for the fan. Could there be some sort of weird electrical **** going on since I have the alternator and fan relay hooked through the same circuit breaker? I also noticed the voltage at the battery posts dropping ever so slightly every few minutes with the car off, kind of like the electrical system decharging or something. Any ideas?

Thanks!

Michael Yount · Aug 12, 2004

Your current hook up should work if the relay is up to the task of handling the current. And now you know why a variable current controller that only runs the fan as hard as it needs to is such an advantage on a fan like this. The spike that the system (wiring, fuse, relay, alternator, fan motor) has to endure on start up is really big (likely between 100-150A), and it shortens the life of all components. With variable current, the spike doesn't occur at all - the controller ramps the current up gradually. Even when mine run, they rarely run at more than 50% speed/current.

But, your wiring approach looks sound - just be sure your wire/fuses/relays are up to the full current and spike demands and you should be ok. Not much you can do about how hard that 50A (plus spikes) hits the system unless you control it differently.

HISSIN50 · Aug 12, 2004

i dont know if you used a freewheeling doide or not - but i would. it is basically a blocking diode, for when the power to the fan is removed, and the fan blade spins like a generator. a 1n5404 diode works (3 amps), per Smithmonte. here is a link to his write up (one of the best write ups i have seen), in case you had not seen it (his site seems to be down sporatically).
http://www.geocities.com/smithmonte/Auto/MarkVIII_Fan.htm

good luck.

Michael Yount · Aug 12, 2004

I've seen this before - 20 years of using electric fans for me - I've never used a diode for this; never had an issue. Perhaps the size of the motor on the MkVIII presents different issues.

HISSIN50 · Aug 13, 2004

Michael, you know way more about this stuff than i do. i figured i would toss that out, as it is supposed to help with relay lifespan (a $3 diode vs a $30 relay). but i dont think that the fan on my older stuff (or bikes) has a diode (not that i looked), so i bet you are right.

but if one was to be frying relays (like Mustang John was), it might be worthwhile.

Rerun · Aug 13, 2004

Bought the diode, and another circuit breaker which makes two (200 AMPS) One for my alternator and one for my fan. Slapped the first diode on, fired up the fan and it blew the diode in half, I'm guessing I had it on backwards? I put another diode on, in a different direction and it didn't blow it the second time. Took the car out for a spin, definate cooling difference. I'm lucky if I see 200* now which is great. It does draw a lot of power, I need to do some more voltage testing. With my lights on, stereo blasting, and fan running, I sit about the N on NORMAL while crusing, not half bad I guess. Damn thing is like a tornado, can feel the air while standing behind the car.

blk92stangg · Aug 13, 2004

Man, I have GOT to get one of those to go with my 3g...rerun, where and how much did you get the fan for, and how much total did it cost in the end? Thanks!

tmoss · Aug 13, 2004

I didn't see nayone mention the fact that is you do not use a wire size (called "guage") large enough for that current, you can overheat the wiring, melt the insulation off it and possibly cause a fire. The diagram above does not mention wire sizes. You want at least a 10 guage wire for the fan power circuit. The relay coil circuit can use 16 guage.

Michael Yount · Aug 13, 2004

Ditto Mr. Tom - and the power 'circuit' includes the ground wire size as well.

Rerun · Aug 13, 2004

Pretty much usin' 8 guage all around, except for a few spots. I.E Toggle switch to relay, etc.

Rerun · Aug 13, 2004

blk92stangg said:
Man, I have GOT to get one of those to go with my 3g...rerun, where and how much did you get the fan for, and how much total did it cost in the end? Thanks!

10$ -> Fan
10$ -> Relay
3$ -> Toggle switch.
10$ -> 200 AMP circuit breaker.

Pretty much it, I already had all the electrical wiring I needed, and miscellaneous things like a soldering iron and stuff like that.

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