Bad alternator - 2zr fe

[tmontague]

I posted a while ago on another thread (I cannot find it) about what "normal" voltage is for the alternator charging output. I stated that I typically saw 12.7 or so and that this always seemed to be the normal for my engine. I also have a slight underdrive NST pulley on my engine.

A while ago my non oem battery died after 3 years (wouldn't hold a charge for more than 4 days) so I picked up a replacement. This replacement started to not hold a charger or crank slow after 4 weeks until it eventually wouldn't start the car. I had it tested and was told it was a bad battery and received a free replacement. Fwiw my smart charger also couldn't properly charge the battery. It kept showing low power and would never go over 60% charged.

Everything was fine until the same problem appeared about 3 weeks after the new battery was installed. This evening when I went to leave work the battery was too dead to start the car. I noticed for the past few days it was cranking slower. I picked up an alternator on the way home from the recyclers (its from a 2011 Matrix). I tested the charging voltage with no load and the old alternator was 12.4 and with load it was 11.6 volts. I installed the new used one and the charging voltage is now 13.9 volts and with load it was 13.6 volts.

This was different then how my Vibe's alternator died as that just suddenly lost power and half the dash lit up and the car was in limp mode. In this case the alternator wasn't charging adequately and over time the battery was loosing its charge until it wouldn't start the car. Not always the most typical way for an alternator to go. I'm pretty sure this was the problem as the charging voltage is much better now, but I won't know until I drive for another month or so. There was a slight whine coming from the old alternator but it was very quiet, I wouldn't have noticed except I checked for it.

As a side, it is possible to remove the alternator on a 2zr without removing the intake manifold or a/c bracket/lines. It's a huge pita but it is possible with some scrapped knuckles

I think I'll keep the old alternator and attempt to rebuild it so I have an extra. I don't think it's worth the $11 core I'd get back. Besides, the one that went bad was one I purchased from the same recycler when I did the swap 2 years ago. I don't trust this one will last for a long time