Alternator questions (L300 gas / 4G64 engine)

[Intrepidor]

I was having some electrical issues on my new-to-me '91 L300 van (gas engine). Wipers were moving slow, lights dim and once I hooked up my multimeter, I was getting intermittent low voltage to the battery. Occasionally it would be in the 14v+ range, but a drive around the block and the voltage would drop down to the mid-12v range.

After some inspection, I found that while the belt was tight, my mounting bolt was just... gone! . I removed the old alternator and found the mounting holes had been ovalized, so ordered a new one. I just installed the brand new alternator (which looks identical to the original one) but am having two head-scratchers:

1: I'd marked the adjustment bolt before removing so I could get close to the original tension, but with the new alternator the adjustment bolt is pretty much bottoming out. again, belts were tight when I remove the old one and as far as I can tell the bolt locations are identical.

2: I have decent tension on the belt, but I'm still only getting mid-12 to low 13 volts to the battery with nothing running, so is there some other reason a brand new alternator might not be charing the battery?

Any advice here would be appreciated!

[thelazygreenfox]

Check and clean the positive and negative battery cables and terminals. The delica wiring is usually undersized so any corrosion can greatly reduce power to the battery. Check each connection carefully for arc spots. If your connections ever loosened before, the wiring could've arced to ground and left an arc spot.

Check/ change your battery. Is it 5 years old. Do a load test if you're uncertain.
Good luck
MD