So something with my 2nd alt system froze up, and destroyed an idler pulley, the belt wrapped around the fan, and proceeded to rip the wire's out of the fan. I ordered new Belt, pulley, Pulley spacer, bolt, and fan clutch.
Can I run this truck on just the main alt, or does it need both. I'm thinking the alt is going, and locked itself up.
This would only be temporary.

 

I think i read on fte with the 2 alternators, the pcm switches between them. DO you have digital gauges? , you could watch the voltage to make sure its always above 13 volts.

 

I watched it on the run home, and everything seemed fine. 13.6vlts. Even though it shredded all the fan wires, it never set a code. I actually just got in, from drilling the broken bolt out of the front cover.

 

If you decide to go from dual to single, you will need to follow this. Read the "background".

https://www.fleet.ford.com/truckbbas/non-html/Q91.pdf

 

Your charging the batteries at that voltage. If towing or hot the fan becomes real important!

 

Thank's guy's!
By no mean's am I wanting to run it like this forever! I am gonna get the alt fixed, and if the belt wouldn't have destroyed the wiring for the clutch fan ($325) I would've already replaced the alt, and been on my way. Unfortunatly, It destroyed the Clutch fan (I'm gonna fix the original as a back up), and that took all the money for the alt.
I see the voltage as the same as before, sooooo.
I ordered a new idler pulley, but am not positive that is my problem. I am thinking the 2nd alt froze temporarily (Everything else is smooth, including the broken idler pulley) and the alt kinda Squeaks.

 

Fan clutch, with and without plow package.
[YB-632]Motorcraft cooling fan clutch(YB632/4C3Z-8A616-AA) - Diesel Filters,Additives,brake rotors, and brake pads for Chevy, Dodge and Ford Diesel Trucks

[YB-3013]Motorcraft cooling fan clutch(YB3013/4C3Z-8A616-SA) - Diesel Filters,Additives,brake rotors, and brake pads for Chevy, Dodge and Ford Diesel Trucks

I also replaced the secondary alt with a upgraded 140amp. They don't advertise the secondary on the website, but when I bought mine it was around $300 with a lifetime warranty. Plus they are located about 10min from house.
PA Performance- You only buy quality once!- 877-471-8010

 

Here is the carnage.

 

Are both alternator's the same?

 

No, two different designs and case size. Also different amp output when in stock form.

 

Do you know what the AMP rating is for the stock dual alternators?

I suspect one is 110 and the other is the 140??

 

CHARGING SYSTEM

The charging system is a negative ground system consisting of the following:
- generator(s)
- internal voltage regulator
- charging system warning indicator
- storage battery
- necessary wiring and cables


Generator
The generator is belt-driven by the engine accessory drive system.

The single generator system consists of the generator mounted on the top right of the engine (diesel) or top center of the engine (gas). The gas
engines use a 3G 115-amp generator with a 2.71:1 pulley ratio. The 6.0L diesel engine uses a 6G 110-amp generator with a 2.79:1 pulley ratio.

The dual generator package consists of an upper/lower dual generator system. The 6.0L upper generator is a VR42 140-amp generator with a 2.79:1
pulley ratio. The 6.0L lower generator is a 4G 120-amp generator with a 3.00:1 pulley ratio. The upper and lower generators are not interchangeable.

In the single generator system, with the key in the ON position, voltage is supplied through the instrument cluster warning indicator I circuit to the
voltage regulator. The regulator grounds this circuit and the charging system warning indicator is illuminated. When the engine is started, the
regulator removes the ground on this circuit and the warning indicator turns off.

On the dual generator system, the PCM controls the charging system warning indicator and commands the lamp on if the PCM detects a concern on
the monitored circuits.

The dual generator system is also monitored and controlled by the PCM. The PCM monitors both the upper and lower generator I circuits to
determine the output of both generators and sets possible diagnostic trouble codes (DTCs). The PCM controls the lower generator by turning it off
when the glow plug system is commanded on by the PCM to avoid possible damage (excessive voltage) to the glow plugs. As soon as the glow plug
system stops cycling, the PCM powers up the lower generator.

The dual generators operate independently of each other. The control is through the internal voltage regulators. If one generator fails, the other
generator can maintain system performance under light load conditions. Under a heavy load, the PCM detects a concern, sets a DTC, and illuminates
the warning indicator.

The set voltage varies with temperature and is typically higher in cold temperatures than in warm temperatures. This allows for better battery
recharge in the winter and reduces the chance of overcharging in the summer.

 

Good thing it is warm here, as I am only using the primary (top) alternator as of now.

 

Lilpooh - GREAT info! reps too

 

Well got the truck the rest of the way together. That belt was a pain in the rear. Had to take the shroud back out, unhook fan, put belt over fan, than trying to keep it on all the pulley's, work the tensioner, and keep the belt on the pulleys, all by yourself suck's! Took about 45 minutes, once I realized the fan had to be unhooked.
Ended up with a 135amp from napa, with a lifetime warranty. Charging at 14.1vlts now.