cooling fan motor

[dagenham]

Does the voltage at the fan motor vary by the temperature of the engine??
It seemed like the fan motor was running slower earlier tonight, then later it seemed like it was running faster. (after I drove the car)
I checked it with a volt meter and got 10.63 volts.

[MikeFleming]

No, voltage should be all same. Ideally.

The vicious fan cycle:
As the bearings in the fan age, they drag more. As drag increases, the fan speed reduces. As the fan speed reduces, the current draw increases. As the current draw increases. the wiring gets hotter. As the wiring get hotter it's resistance increases so the voltage at the fan goes down - and causes it to slow down and draw more current. The fan controller relays and harness connectors are a part of the wiring.

Inspect/repair the wiring and fan controller and replace the fan motor. Don't forget the pigtail connector from the harness to the fan motor.

[Jay4hand]

Just use a MkVII fan, its faster, moves more air, and has a very low profile.

[Gyrhead]

I think I still have a few NOS motors from the Gyrhead days. Not the cad plated ones tho. The black cased Ford service replacement ones. Aftermarket Delco ones are around $35. I'll hook you up.

[dagenham]

I replaced the relay and noticed that the motor was still spinning the same speed as before. When I say I checked the voltage at the motor I ment coming out of the pigtail itsself.
Like I said, when I hooked the motor direct to the battery it ran fast enough to make a loud roar.
I dont beleive the bearings in the motor are bad because I have spunthe fan by hand and it feels very smooth and free yet.

[Meotchh]

I would hope it spins faster with a direct connection to the battery. Providing you are using a heavy gauge pair of wires you will have less voltage drop across the wires which will also supply less resistance to current flow & therefore spin the fan up pretty fast. The 30yo wiring in your car has been heated, cooled, stressed & abused. The wiring in the car will not supply the same amount voltage due to the greater distance & resistance to current flow. You also have the ~50ohm coils in the relays which will drop some voltage. How much of a difference in RPMs are you seeing?

[SVO4PWR2]

Anyone know what the cfm of a stock fan?

-RICH-

[MikeFleming]

The voices just yelled out 1400.

And I have no idea where they got that number.

That assumes 14.0 VDC system voltage, a new motor and good wiring.

[SVO4PWR2]

Thanks Mike.

Also at what temp does the "Stock" coolant switch "fan control" close and open?

I was thinking of changing over to an aftermarket set up that i use in my SVO but seeing what the stock fan puts out
i might not do anything except put in a Bosch relay for the fan.

BTW its for a 2.3T Capri thats been sitting for years.

-RICH-

[caroth]

Another fan option is the Ranger Duratec fan that is mounted as a pusher in the Ranger. I have been running one of these fans for years as a puller and it works great and doesn't pull near the amps of the Mk7, SC, or Taurus fan. You can see images of it mounted on this page: http://www.rothfam.com/svo/wiring.htm It is not a direct bolt on, I used 3/4" delrin for the mounting posts, drilled and tapped each end and used normal body bolts to give it an OEM look.

[MikeFleming]

Also at what temp does the "Stock" coolant switch "fan control" close and open? 221-222 degrees F.

[SVO4PWR2]

221-222 degrees F

OK, i took out the fan switch it had a lot of crud on it so i cleaned it.
I tested it, its working.

Is there any benefit to running a cooler "< 220*" switch. I had to put in a new rad since the original was starting to look funky
and the coolant had seen better daze. It looks like the RS is going to get a full cooling system overhaul....heatercore headn' your way Pat :stick_poke:

-RICH-

[NY eric]

RELAYS!!

As much as I hate to modify stuff a set of relays for the fan motor, foglight switch and headlights can make a big difference. I personally dont trust the 80s wiring harnesses. I have seen too many car-B-Qs. We have very few of these cars left and I hate to see them go up in smoke.

Rule of thumb if it doesnt seem right it probably isnt...