Symptom: Alternator works fine for a few miles then cuts out. After driving for like 10-15 minutes, the alternator kicks back in and work fine for a while, then it will cut out again for a few minutes, then it works again. I'll turn off the car, then start it up it will work or it won't work. A random pattern, but frequent.

2 weeks ago my alternator was bad and I replaced the diode and the voltage regulator. It was working fine till the last 2 days till this problem started. I first thought a bad connection or a short in the charging system. I checked the wires and the connections. All are good.

Any idea's?

 

Update. I had the alternator and the battery tested and they both passed. The belt is good condition and is tight.

 

Did they test it for 10-15 min.?

 

No. You know those Autozone/Pep Boys/Kregan guys. They run it on the machine till the machine stops with a Pass-Pass-Pass.

 

How do you know it's the alt.? The dummy light or the voltmeter dropping? Is the case getting hotter then normal? What about the charge wire, is it getting hot? What's the alt. really putting out (check with a volt meter at the back of the alt.)? Also check and see what the voltage drop on the charge wire is. Just use you volt meter, one end on the battery +, the other end on the alt. +. If things are getting hot, or you have a large voltage drop, it would indicate something is pulling to much current. If that's all good, I'm thinking something is up with the alt.? But lets start with cheap fixes first...

 

Something I'm noticing. I tightend the belt even tighter and it seems to be working more often but it still will fail, but it will come back on, just on and off more periodicly. Also sometimes, it will rise up to 14.5 volts only when the engine is reved up, but later will stay at 14.5 volts at a low idle speed. For some reason I'm thinking it has something to do with the brushes. The brushes are new and installed the same why the old ones were installed, but what I think its the core itself. This was the second time I repaired that alternator, plus it was a remanufactured one. Is it possable to be the core of the alternator? That dosent come with the repair kit.

 

Where are you measuring this 14.5V and how? Just want to make certain it not some bad connection causing a intermittent voltage drop making things dim and the dash gage drop.

 

After having a brain lock on this issue. I desided to take the car to a electric shop. The problem was the Alt., the 2 little wires to the Alt were bad, and the battery was bad.

What makes me mad is the battery. The battery was almost 9 months old and still under warrenty. I had it tested at the same place I got it (Autozone) about 2 or 3 weeks ago and they said it was good, and it just needs a charge. I got it from them because the last place (Sears) I had bad issues with the battery and its warrenty.