On a trip out of town for a weekend at a friends lake house my alternator died. Of course it's Saturday afternoon in a small town so the only replacement available was a duralast gold, so bought it and got back on the road. Thank God the alternator is so easy to get to! The batteries checked out ok, just needed some water. I kept my OEM core to get it rebuilt, but what I don't get is the only indication of a problem was my ac wasn't blowing cold air, I assume it was because there wasn't enough voltage to hold in the clutch, but outside of that the truck ran fine, I didn't get any other lights or warnings. Weird. Should I check anything else out?

 

i've done a few "on the road" repairs to my guy's Vans on the road using the same Duralast alternator...they work just fine, one of them has around 50K on it, I prefer buying a rebuilt from Ferd but at 8PM stranded...it is what it is! As far as checking anything, you could just verify it's charging w/ a meter if u wanted but probably not necessary if no battery light and everything is working including bright headlights.

 

Get yourself one these digital voltage meter and leave it plugged in to your cigarette lighter outlet and you can monitor your charging voltage (14.3v), your glow plug operation (drops to 11v if working properly for a one minute on a cold start) and your battery voltage (key off).
Amazon.com: Vector VEC008 Digital LCD Voltmeter, 12 Volt: Automotive

 

Keep in mind that if your batteries are severely discharged, but just enough juice to re-start the engine, a new alternator will have a lot of stress put upon it trying to get them fully re-charged.This is especially true if at night where there are even more demands put upon it. That's when it will get its hottest, and is the most likely time for any premature failure to happen.

Ideally, a new replacement alternator should begin it's life by just keeping two fully-charged batteries up-to-snuff. If you were in your garage, it would be a good time to hook up the external charger, a few hours before the change-out.

I know, it isn't always an ideal world out there.....

Pop

 

You got that right - Murphy and his stupid law! The batteries are sitting at 12.99 right now, but s.g.'s are in the 1.17 area. I'll put them on an 8hr slow charge and see if I can't get those up where they should be. My charging voltage with the new alt stayed in the 13.6 - 13.9 range. Does this seem a little low? I'll see what putting a good charge on the batteries does for that, too. btw, Springerpop, in another thread you said you think the average life for an oem starter with no mods is about 140k, mine crapped out at 138.7, so I guess I'm a little below average!

 

Your 13.6 - 13.9 should go up abit when the batteries come closer to full charge.

 

Funny this must be an "alternator" weekend - alt went on our 03 TDI Sat. Had to replace it in a parking lot in the heat. - they never go when it's "convenient" ended up w/ a reman from O'riellys never tried any reman'd parts from them I'll have to wait and see how it fairs. I didn't have many options - they were the only one that had one in stock. Alt looked good - nice & clean with all the hwde right out of the box. No pulley on it though which forced me into an extra trip to let them change it out at the parts store

 

The SuperDuty alternators have a "set point" of between 14.4 and 14.7 volts, and that's about what you should be seeing when taking a measurement across the battery terminals when they are virtually fully-charged, and after the glow plugs have "timed out".

Because the glow plugs draw so much current, if their relay is still activated, you can't make anywhere that voltage, and it will read around 12.6-12.7 volts. Once the relay shuts off, it will jump up to around the set point. That should take no more than about two minutes from key on.

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