Alternator questions (L300 gas / 4G64 engine)
Posted: Sat Feb 08, 2020 2:42 pm
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!
After some inspection, I found that while the belt was tight, my mounting bolt was just... gone!

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!