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Discussion Starter · #1 ·
(Alfa Spider 1991.)

Hey folks, I have a problem- My alternator was going bad (hard starts, fading radio & horn, etc) so I had it replaced a few days ago.
When I got the car back, I noticed the battery gauge on the dash (top right) was showing weakening battery (needle moving left) and the same old symptoms-fading horn & battery. Signal would get stronger on highway driving but drop when on side roads or if accessories were turned on.
Last night after work, car started, turned on lights and drove home –but had no horn and no radio. Battery needle was almost all to the left (dead) but the car drove all the way home with lights. NO BATTERY LIGHT/WARNING CAME ON EVER.

When I got home, battery needle was almost all to the left and car would not start.
Battery is an Optima about 2 years old.
Could the new alternator be defective or installed wrong? Most mechanics are clueless with Alpha wiring.

Suggestions?
 

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just start her up, put a voltmeter across the battery and look for about 13.5-14v - if you have that your alternator is Ok

It sounds as though you have a power drain this points to the voltage regulator- take out the voltage regulator on the back of the !new! alternator and check the brushes are good. If they are worn unevenly go back to the guy who sold you the alternator!
But I would in any case go through the various earth connections to make sure they are clean. Bad earths cause nightmares in electrics/charging/starting -;)
 

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You can check the output of the alternator when running, as well as what the battery is actually seeing with a volt meter. There are a few places where poor connections can cause charging issues. First off, does the battery light come on with the ignition then go out once the engine starts? It should. If not, you may well have a connection issue with the "exciter" wire circuit to the alternator (small green wire on my '80). If this circuit is open (bad connection, burned out bulb, etc.), the alternator will not be able to generate power. My guess is that your problem lies there. You can check it by checking the voltage on that wire with the ignition on, but engine not running. You should see voltage there, although it will not be as high as battery voltage. If there is no voltage at the exciter wire, you will have to trace back to find the problem.

If the battery (really the alternator) light operates properly, then I would check the alternator to battery connections and engine to chassis and battery to chassis ground connections.

I had a similar issue with my '80 Spider. In my case the previous owner had replaced the alternator, battery and starter, but the car continued to crank poorly when hot and the battery would run down in time. In my case the ground strap from the bell housing to the chassis was at fault, even though it was clean and LOOKED fine. With a new strap the car cranks well hot or cold and the battery charges properly.

Steve
 

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Qmulus is on the right track...I had the same problem...took my 91 Spider in to have the water pump replaced, once this was done, they told me the car would not hold a charge(did not have this problem before I took the car in) and I need an alternator, so I got an alternator from IAP, they replaced it and told me it still would not hold the charge, so they replaced the battery, which was still under warrenty, still would not hold a charge, and they told me they give up...had to take it to an electrical place, turned out when replacing the water pump they blew a fuse for the alternator light...the electical guy replaced the fuse and has been holding a charge fine for months...moral of the story, did not need a alternator, or a battery, what I needed was a machanic that knew what he was doing..hope it works out for you...
 

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...Battery is an Optima about 2 years old...
Along with checking everything else, go have your battery tested. Your Optima should still be under warranty. If you got it at Kragen/O'Riley, they should just swap it out. That's what they did for me earlier this year. Had a 3 year warranty, they tested it, initial test ok, deep cycle testing was bad, swapped with new one, gave me another replacement warranty for 3 years from date of exchange.

Seems the Optimas will work great until they don't. When they go bad, they go bad almost instantly. They will work, show fine on a volt meter, but won't hold the charge for very long.

Either way, take advantage of your warranty. You may get a brand new one and should get another 3 year replacement warranty on top of it. FWIW
 

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Discussion Starter · #6 ·
Thanks guys, off to do these checks.
 

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N4S,

I may have missed it as I scanned the posts above, but there is a recurring thread about the main power wire that goes from the alternator to the junction box on the left fender well. Fabricate and put in a new one. Feel free to use a heavier gauge wire than original. A visual inspection of the old one will NOT tell you whether it is working. You will save a lot of heartache if you just go ahead and change it.

I left the original wire in place rather than try to fish it out from the bundle it was with, and simply ran a new wire from the B+ terminal on the alternator the junction box stud/nut on the left fenderwell. A few wire-wraps, and bingo, all better.

Meanwhile, I had purchased a rebuilt alternator. Fortunately, it was "core free" so I still had my original unit. This was useful when the bearings went out on the rebuilt about 2 years and 3,000 miles later, locking up the alternator, burning off the belt, and shutting me down on the road home in a heavy rainstorm.

I simply re-installed the original alternator which continued to work fine until I sold the car. I assume it is still working.
 

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that junction box is sometimes overlooked, i agree - worth unbolting the wires, and cleaning the connections - done in 5 minutes:)
don't break the little plastic tabs when removing the top to the box!
 

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I left the original wire in place rather than try to fish it out from the bundle it was with, and simply ran a new wire from the B+ terminal on the alternator the junction box stud/nut on the left fenderwell. A few wire-wraps, and bingo, all better.
I did the same thing (ran a second 8ga wire in parallel) and it didn't change squat voltage-wise. YMMV, of course.
 
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