Stock harmonic balancer help

[Socal Mach]

The stock harmonic balancer on my 2004 Mach failed last year so I replaced it with an OEM replacement from the parts store. Since I've replaced it the battery isn't charging correctly. It has a new alternator and battery, it's only putting out around 12.5 volts. The battery reads the same.

The stock pulley is about 5.5" across and the new pulley is around 7". I ordered a 2nd one recently which was the same size both showed OEM replacement. Ford no longer makes the stock pulley any one know where I can get a pulley that isn't an underdrive pulley?

Any help is much appreciated.

 

[DSG2003Mach1]

there are aftermarket pieces out there - innovators west, ati etc... I want to say Summit has a cheaper brand as well. Not that it really matters but these are just vibration dampeners, they're internally balanced.

If a bigger crank pulley makes more boost it's spinning the blower faster, shouldn't it be spinning the alternator faster then? I thought under drive pulleys gave you a smaller crank pulley and bigger accessory pullies.

Was the alternator replaced before or after the crank pulley and what alternator? A lot of these rebuilds/remans (even OE) are bad out of the box

 

[Socal Mach]

I've never messed with pulley sizes so I'll have to read up on them.

The crank pulley was replaced first. I took a reading of the original alternator of around 12.5. I replaced it with a Duralast alternator. It reads right around 12.5 as well. That's why I'm coming to the conclusion of the pulley being the issue.

Also, it's a new battery as well.

 

[DSG2003Mach1]

I've never messed with pulley sizes so I'll have to read up on them.

The crank pulley was replaced first. I took a reading of the original alternator of around 12.5. I replaced it with a Duralast alternator. It reads right around 12.5 as well. That's why I'm coming to the conclusion of the pulley being the issue.

Also, it's a new battery as well.

how are you measuring voltage - with a meter at the battery or something connected to the OBD2?

 

[Socal Mach]

Multimeter at the battery and the alternator.
The battery is reading pretty much what the alternator is reading.

 

[DSG2003Mach1]

Multimeter at the battery and the alternator.
The battery is reading pretty much what the alternator is reading.

question was mainly because there is frequently a decent variance on the OBD 2 readout, it might show .5 less than at the battery (ie 13 at the battery becomes 12.5 via obd2)

 

[Socal Mach]

I got ya. Thank you for the tour inputs so far.

 

[01yellercobra]

Bigger crank pulley would spin the alternator faster. The pulley isn't your issue. I'd get the alternator load tested. New doesn't mean good.