Replacing the Alfa’s Alternator

I just recently came across these photos, which I had frankly forgotten about, which is why this technical procedure, performed in May, is only getting its own blog post now.

 

If your memory is good, then you’ll recall reading back in May’s report on this year’s New England 1000 that the Alfa’s alternator failed us in the middle of the rally. If your memory is not so good, or if you’re just joining us, you can read about it here.

The truth is, I should have been wise to an impending failure, as even with the Red-Top Optima battery on trickle charge, the car would still occasionally need a boost. Alternator output measured at the battery was barely 13 volts, a weak statistic which I rationalized to a low idle.

As mentioned in the rally write-up, the drive to our starting destination was done in a steady rain, with lights blazing and wipers flailing. It’s likely that was enough to seal the fate of the battery.

Tuesday morning, we bought a NAPA-brand battery, and leaving the Optima in its place in the trunk, we simply swapped the cables onto the new unit, using bungee cords to keep it from sliding around. The alternator wasn’t completely dead, just on life support. With the new battery, we had zero starting issues the rest of the week, and coasted home on Friday.

Once again I must give a shout to my friends at Classic Alfa in the UK. A new alternator, ordered Tuesday afternoon after they had closed for the day, arrived at my house on Thursday evening. I dare say that most U.S.-based suppliers would not have been able to get me one with such speed. So Memorial Day weekend was spent in part performing the alternator-ectomy.

Old alternator and attendant wiring connections

Access to the unit in the engine compartment was quite good, improved by the battery’s relocation to the trunk, performed by the previous owner (PO). The PO had also removed the factory generator (which I still have) and installed this alternator plus an external voltage regulator. My new replacement alternator has an internal regulator, and it’s a so-called one-wire job.

 

Old one again. Note alignment of upper bracket.

I photographed the wiring to help with any reinstallation questions, then removed the two components. I noted that the alternator’s upper mounting bracket was at a slight angle, and vowed to focus on improving that geometry when putting it all back together.

With everything hooked up, I measured a steady 13.8 volts at the battery (yet another new Red-Top that I purchased to be on the safe side). I was able to recover the old Optima by very slowly trickle-charging it, and both that battery and the barely-used NAPA one were sold to a young man in my office who is always working on 3-4 project vehicles at a time. (And for the record, both the old alternator and regulator were put in the trash. I don’t keep worn-out parts around.)

New alternator in place, and better aligned too

The only issue, and it’s the smallest of nits to pick, is that the one-wire alternator needs to be ‘excited’ after initial start before it will charge (much the same can be said about me). The ammeter reads zero until I bring engine revs above 3,500 rpm (waiting a few minutes so that oil circulates), at which point, the amp gauge needle jumps to life. It’s a small price to pay to be secure in the knowledge that the battery’s got the juice to crank that 1300cc monster to life.

 

A good number

 

All photographs copyright © 2018 Richard A. Reina. Photos may not be copied or reproduced without express written permission.