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Old 04-11-2011, 08:27 PM   #1
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MarkVIII fan wiring info

I am putting together a lincoln mark VIII fan setup to take care of the cooling duties. Ive been doing a lot of research inside and outside the corvette community and there is a lot of conflicting info out there. Below is a part list which Im planning to use. If you have any experience in this area take a look and post your comments. I am working on a clear wiring diagram which I will post and can serve as a reference for all those doing this swap.

Lincoln MarkVIII fan sourced from craigslist.
Tyco 75 Amp relay Tyco 75 Amp relay

Bussman 50 amp circuit breaker
Zirgo 180 degree temp switch
180 degree thermostat
CS144 alternator 140 Amp (still looking for a source)
8 gauge wire (unless someone can make an argument for 10 gauge)

My local radiator shop will weld in a 3/8NPT bung into the cold side radiator tank about 6 inches above the outlet. Since the radiator is not grounded I am thinking of finding a 3/8 eyelet to run a wire to either the chassis or back to the alternator. I will also hook up a manual override switch in parallel to the temp switch.

Thoughts? I hope to have a full diagram later this week after I incorporate any comments from this thread. I will also follow up with a full install thread and cost breakdown.
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Old 04-11-2011, 08:59 PM   #2
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....Ford & Chevy....isn't that like pouring antifreeze in your
crankcase....

....I'm going to follow along to see the outcome, creative
thats what it is all about....

Quote:
Originally Posted by Double_Take View Post
I am putting together a lincoln mark VIII fan setup to take care of the cooling duties. Ive been doing a lot of research inside and outside the corvette community and there is a lot of conflicting info out there. Below is a part list which Im planning to use. If you have any experience in this area take a look and post your comments. I am working on a clear wiring diagram which I will post and can serve as a reference for all those doing this swap.

Lincoln MarkVIII fan sourced from craigslist.
Tyco 75 Amp relay

Bussman 50 amp circuit breaker
Zirgo 180 degree temp switch
180 degree thermostat
CS144 alternator 140 Amp (still looking for a source)
8 gauge wire (unless someone can make an argument for 10 gauge)

My local radiator shop will weld in a 3/8NPT bung into the cold side radiator tank about 6 inches above the outlet. Since the radiator is not grounded I am thinking of finding a 3/8 eyelet to run a wire to either the chassis or back to the alternator. I will also hook up a manual override switch in parallel to the temp switch.

Thoughts? I hope to have a full diagram later this week after I incorporate any comments from this thread. I will also follow up with a full install thread and cost breakdown.
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Old 04-11-2011, 09:28 PM   #3
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Quote:
Originally Posted by Double_Take View Post
Lincoln MarkVIII fan sourced from craigslist.
Tyco 75 Amp relay

Bussman 50 amp circuit breaker
Zirgo 180 degree temp switch
180 degree thermostat
CS144 alternator 140 Amp (still looking for a source)
8 gauge wire (unless someone can make an argument for 10 gauge)
Are there any "pic & pull" salvage yards around you? That's where I found my Taurus fan for $25. Cleaned up very well and looks great. I've had no issue with my 10 gauge wire and 30 amp fuse, but I only run the low speed. No harm in oversizing the wiring and breaker. The 140 amp alternator might be overkill depending on your other accessories. I'm getting by fine with a 100 amp Powermaster but I don't have a radio or A/C.

With a good size aluminum radiator I haven't needed the high speed fan at all. I've been running off a temp switch in the location you mentioned, but will probably change to a slightly hotter switch near the top of the hot side tank. That will help keep the wiring harness shorter since I'll be getting power from the horn relay rather than the starter lug.

If you haven't read through my thread on the Taurus fan you might find some useful tidbits in there.

Looking forward to the write-up
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Old 04-11-2011, 11:03 PM   #4
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Quote:
Originally Posted by 92Roadster View Post
....Ford & Chevy....isn't that like pouring antifreeze in your
crankcase....

....I'm going to follow along to see the outcome, creative
thats what it is all about....
Im an equal opportunity engineer. The fan is the best thing ford ever made. However it does not move as much hot air has the ford fan boys spout.

Quote:
Originally Posted by lsejlowe View Post
Are there any "pic & pull" salvage yards around you? That's where I found my Taurus fan for $25. Cleaned up very well and looks great. I've had no issue with my 10 gauge wire and 30 amp fuse, but I only run the low speed. No harm in oversizing the wiring and breaker. The 140 amp alternator might be overkill depending on your other accessories. I'm getting by fine with a 100 amp Powermaster but I don't have a radio or A/C.

With a good size aluminum radiator I haven't needed the high speed fan at all. I've been running off a temp switch in the location you mentioned, but will probably change to a slightly hotter switch near the top of the hot side tank. That will help keep the wiring harness shorter since I'll be getting power from the horn relay rather than the starter lug.

If you haven't read through my thread on the Taurus fan you might find some useful tidbits in there.

Looking forward to the write-up
I found a guy who parts out mark viii's and got it for $50. IMO thats a good deal. From what I read the mark8 pulls more power than the taurus so im being extra safe with the electric components. The temp switch location and temp is where lots of people differ in opinion. IMO I want the fans to come on only if the water leaving the radiator is hotter than desired. If Im driving the radiator should be doing its job and cool the water on its own. If im am stationary the water will heat up and kick on the fans. I dont care what the temp is coming out of the engine. I hear that the 195 temp switches tend to switch in the 195-200 degree range and the zirgo listed above tends to switch on in the 185-190 range. This way I always have cool water when the thermostat opens. Since the thermostat opens slowly I should be running somewhere in the low 190's.
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Old 04-12-2011, 06:34 AM   #5
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Here is a diagram I made for a single fan like a Taurus or Mark VIII fan.



The T-stat is the best controlling method. The relay will be triggered as long as the IGN system is energized but the fan won't run unless the T-stat closes the relay ground through the block or head based on coolant temperature.

Once the relay ground is closed, the relay activates, powering the fan with the 12V source.

The best source for the fan is NOT the alternator...but the BAT junction at the starter. That's the best 12V source you'll get outside of a direct line to the battery.
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Old 04-12-2011, 08:39 AM   #6
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Quote:
Originally Posted by Double_Take View Post
Im an equal opportunity engineer. The fan is the best thing ford ever made. However it does not move as much hot air has the ford fan boys spout.



I found a guy who parts out mark viii's and got it for $50. IMO thats a good deal. From what I read the mark8 pulls more power than the taurus so im being extra safe with the electric components. The temp switch location and temp is where lots of people differ in opinion. IMO I want the fans to come on only if the water leaving the radiator is hotter than desired. If Im driving the radiator should be doing its job and cool the water on its own. If im am stationary the water will heat up and kick on the fans. I dont care what the temp is coming out of the engine. I hear that the 195 temp switches tend to switch in the 195-200 degree range and the zirgo listed above tends to switch on in the 185-190 range. This way I always have cool water when the thermostat opens. Since the thermostat opens slowly I should be running somewhere in the low 190's.
You've got it right.
Let the fan control the coolant temp out of the radiator and let the tstat control the engine temp. The more consistant the temp of the coolant entering the engine the better. Here in S Florida, fans sometimes work even at cruise speed.

Kepp the fan power wires as short as possible t keep the voltage drop down.
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Old 04-12-2011, 08:45 AM   #7
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Quote:
Originally Posted by D_B View Post
Here is a diagram I made for a single fan like a Taurus or Mark VIII fan.



The T-stat is the best controlling method. The relay will be triggered as long as the IGN system is energized but the fan won't run unless the T-stat closes the relay ground through the block or head based on coolant temperature.

Once the relay ground is closed, the relay activates, powering the fan with the 12V source.

The best source for the fan is NOT the alternator...but the BAT junction at the starter. That's the best 12V source you'll get outside of a direct line to the battery.
Thanks for the post. I have seen arguments for connecting to the starter and directly to the alternator.

For example this post from the Taurus install thread.

Quote:
Originally Posted by 1 MN MCN View Post
Couple of things that you might find useful. The ideal place to draw your power for your fans is at the + Power terminal of the Alternator, that way the current goes right into the fans from where it's being generated, Shortest possible run, direct, and it won't register at all on your in car ammeter. No advantage from running it from the + batt terminal, the current actually has to flow from the Alt to the batt terminal now.
The alternator senses the voltage at it's sense input to control it's output, it's voltage controlled.
To keep the fans off after you turn the ign off, disconnect the relay control voltage (+ side of the relay coils) from the 30A fuse fan power, and reconnect it to the ACC tab from the ign box. that way, when you cut off the power, you cut the relays ability to close, regardless of the state of the temp switches, and they are also off during cranking of the motor (enabled now by the ACC state). This also has the advantage of making sure that the alternator is always supplying the power to the fan, and not the Batt, keeping it from draining and leaving you stranded.
What is the advantage of running power from the starter? If the fan is running juice now has to go to the starter (through the fusable link) then the fan.

If the t-stat is closed, by definition the water in the block is colder than the t-stat opening temp (lets call it 180 for now). Over time the water in the block will approach 180 signaling the t-stat to open. If the temp switch is in the head and the turn off temp is lower than the 180 wouldnt the fans run continuously?

These are some of the questions I found unanswered. A healthy debate should come up with the best designed electric cooling fan system for our cars.
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Old 04-12-2011, 08:57 AM   #8
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One nice thing about pulling power from the starter is that you can watch your ammeter to see when the fan is on. You won't get that pulling from the alternator, but that's a pretty minor consideration.

As for the temp switch location, I used the same logic you did: let the T-stat control engine water temp and the temp switch control radiator water temp. Makes good sense
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Old 04-12-2011, 05:52 PM   #9
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The reason for NOT wiring fans directly to the ALTERNATOR is several fold-

The battery acts as a bank account...The fan(s) are a bill (House note- it's a big draw) and the alternator is your income. You would NEVER want to have your house payment taken directly out of your paycheck....

The battery stabilizes the loads - like the current surge when your fan(s) start up. If your sitting in traffic, idling- alternator is not spinning fast enough to create enough current to start up the fan(s) -that's were the problem starts...

The battery also filters the AC ripple created by the alternator- electronics (MSD/Stereo) don't like this- however this is less important w/ lights & fans.



These cars were NOT/never designed to handle these large amounts of current.- GM lucked out by putting the battery in the cabin- protected from heat and cold.

You should- unless you have "Agreed Value Replacement" insurance-UPGRADE the alternator AND the output wire off the alternator when adding a fan...

Run a large gauge wire from alternator output to the starter terminal - the wire from the starter to the battery should be 4GU or larger.

Bigger is better
8 GU can handle 150 amps
10 GU can handle 100 amps
12 GU can only handle 60 amps

REMEMBER- these are MAX "ballpark" rating at 70 degrees w/ copper wire...rating goes DOWN as temp increases-and if bundled, rating goes down as well. And how hot is it underneath your hood????

The ratings are basically how "HOT" a wire can get "safely!!!" Isn't that an "oxymoron?"

So why not spend the few extra bucks for the thicker wire? I personally think 10GU is too small for a CS 144....

The next trick is to run the wire SAFELY from the Alt to the starter- wire ties-split loom tubing-away from heat and moving parts...

I don't like to put safety devices in the path- fusible wire/fuses/circuit breakers...If you have done your job correctly protecting the wire from a short- these devices do nothing but slow down the flow.


As far as an ammeter- they are not that great at telling you what's really going on- Rather how fast you money is moving in and out of your bank account not HOW MUCH...
Upgrading your wires will cause the ammeter to read incorrect. However, have seen a few threads on replacing w/ a voltmeter.

Richard
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Old 04-13-2011, 07:37 AM   #10
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When converting old rides to electric fan I take a cue from modern rides......

Add a two post terminal block to the + battery cable, there's nice ones in late model wrecking yards. They've even got fancy red flip top covers.

Now, route a 4 ga cable from the terminal block to the car's original underhood power point. In this case, the starter.

Going forward, the fans, headlight relays, security system relays, heavier gauge alternator wire, etc can all be moved to the new terminal block. It's up away from starter heat & oil and just generally a better setup all around. Easier service, greater expansion room, etc. I get so irritated that chevy powered most of their cars off a low point on the engine that's typically oily and burning hot when trouble arises.

good luck!
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Old 04-13-2011, 09:01 AM   #11
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Quote:
Originally Posted by Richard454 View Post
The reason for NOT wiring fans directly to the ALTERNATOR is several fold-

The battery acts as a bank account...The fan(s) are a bill (House note- it's a big draw) and the alternator is your income. You would NEVER want to have your house payment taken directly out of your paycheck....

The battery stabilizes the loads - like the current surge when your fan(s) start up. If your sitting in traffic, idling- alternator is not spinning fast enough to create enough current to start up the fan(s) -that's were the problem starts...

The battery also filters the AC ripple created by the alternator- electronics (MSD/Stereo) don't like this- however this is less important w/ lights & fans.



These cars were NOT/never designed to handle these large amounts of current.- GM lucked out by putting the battery in the cabin- protected from heat and cold.

You should- unless you have "Agreed Value Replacement" insurance-UPGRADE the alternator AND the output wire off the alternator when adding a fan...

Run a large gauge wire from alternator output to the starter terminal - the wire from the starter to the battery should be 4GU or larger.

Bigger is better
8 GU can handle 150 amps
10 GU can handle 100 amps
12 GU can only handle 60 amps

REMEMBER- these are MAX "ballpark" rating at 70 degrees w/ copper wire...rating goes DOWN as temp increases-and if bundled, rating goes down as well. And how hot is it underneath your hood????

The ratings are basically how "HOT" a wire can get "safely!!!" Isn't that an "oxymoron?"

So why not spend the few extra bucks for the thicker wire? I personally think 10GU is too small for a CS 144....

The next trick is to run the wire SAFELY from the Alt to the starter- wire ties-split loom tubing-away from heat and moving parts...

I don't like to put safety devices in the path- fusible wire/fuses/circuit breakers...If you have done your job correctly protecting the wire from a short- these devices do nothing but slow down the flow.


As far as an ammeter- they are not that great at telling you what's really going on- Rather how fast you money is moving in and out of your bank account not HOW MUCH...
Upgrading your wires will cause the ammeter to read incorrect. However, have seen a few threads on replacing w/ a voltmeter.

Richard
Excellent post. That is the technical details I was looking for. I will work on a wiring diagram today and have it up tonight.

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Old 04-13-2011, 11:03 PM   #12
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"If you ever injected truth into politics you'd have no politics."
Old 04-14-2011, 08:50 AM   #13
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here's a silly question... What is your "ignition" power source? Isn't the horn relay only supposed to have power when the key is on? That's what I thought was the case, but when I checked mine I have 12V there at all times. Did bubba really screw up my harness?
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Old 04-14-2011, 09:49 AM   #14
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Quote:
Originally Posted by lsejlowe View Post
here's a silly question... What is your "ignition" power source? Isn't the horn relay only supposed to have power when the key is on? That's what I thought was the case, but when I checked mine I have 12V there at all times. Did bubba really screw up my harness?
The horn relay lug is just a junction block, same as the batt term on the starter, hot all the time.
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Old 04-14-2011, 10:03 AM   #15
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Quote:
Originally Posted by lsejlowe View Post
here's a silly question... What is your "ignition" power source? Isn't the horn relay only supposed to have power when the key is on? That's what I thought was the case, but when I checked mine I have 12V there at all times. Did bubba really screw up my harness?
I assumed I would tap into the ignition wire going to the starter solenoid.

What is the best keyed 12V source?
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