Help Needed Alternator???

[wcsmithiii]

2004 250 Super Duty 4X4 6.0 ran good for three weeks after replacing the FICM and having the alternator repaired. Ran good on a short run for groceries (about 4 hrs) stopped for about 2 hrs then tried to start and all I got was the dead battery chatter. Replaced both batteries with Optima's (800 CCH) now it starts up and runs good. Problem is, checking the voltage at the battery with the engine running is only 12.3V. I'm use to seeing at least 13V. Checking the voltage at the alternator:12.5 at the heavy post, checking the two pins on the plug (key on) .03V (key off) 12.3V......I'm stumped. Any ideas????

 

[DaveBen]

You should get 13.8 volts at idle. If not you will need a new alternator.

Dave

 

[wcsmithiii]

Thanks

That is what I thought. However, being new to the oil burning world I prefer to verify especially with the degree of difficulty involved with the removal of the alternator. I do appreciate your help.

 

[DaveBen]

The alternator is right on top. Removing and replacing it should not be too tough. Getting to the belt tensioner may cause you more problems. Cut the shroud along the lines to the sides and remove the top section. This will give you a fighting chance. The shroud can be reattached using a couple of small bolts.

Dave

 

[wcsmithiii]

My apologies for the delay. This morning went to check all voltages:
Not running w/ key on red/green wire 11.95
Orange/blue 12.11
key off red/green 12.19
orange/blue 0.0
Battery passenger side 12.21
Battery drivers side 12.21

Truck running: Battery passenger side 13.16 climbed to 13.45
drivers side 13.20 climbed to 13.45
I stopped monitoring at this point to seek further assist. The truck was running at idle for all readings (fired right up and ran smooth all the time). When you say 13.8 is this at initial cranking or is this after recharging for a few minutes? Or should I monitor for a few days (a while any way) to see how it goes. I am a firm believer in "Don't fix if it ain't broke".