Start of an alternator problem?

[joetiii]

I noticed today that the lower red lamp on my oil pressure guage stays on when I first start up the car. I have noticed this in the past when starting but the light went out after I got the RPMs over 1500 or so. Today I noticed that the light stayed on even after I reved up the motor to 2k. Went out after 40 seconds or so by itself, regardless of RPM. Do I have a loose connection perhaps, or is something starting to go bad in the charging system??

[oneblueyedog]

It could be a diode in the alternator going out.

Or, in one case I had a wire from the voltage regulator pinch between the voltage regulator housing and the alternator body and that made the red light glow.

You could get it tested in the car to see what it's doing. You measure voltage over the battery terminals with a Voltmeter. With it charging I think it will read 14V. But check in the archives with a search. I think you check it with the lights on with engine running.

When I had a bad alt it read 12, 11.9, 11.7....then wouldn't crank.

[joetiii]

I think I'll start by tightening the belt, then test voltage at the battery. Will report back.

[joetiii]

So belt tension was fine and the voltage at the battery was 12.2 volts, so I changed out the alternator. $500 and it still tests 12.2 volts at the battery

What next????

Battery load is 620 cranking amps and shows 13 volts with the ignition key off

[oneblueyedog]

Is the red light still glowing?

[oneblueyedog]

Is the Voltage regulator on the alternator or on the fuse/ relay panel?

[joetiii]

The dash light stays on constantly. The ground strap is a bit worn but still solid on both ends. When the car is running, the voltmeter reads a little over 12 volts. When the car is off, the voltmeter starts to rise. I understand that there should be 12v at the starter and 12 at the lamp wire to excite the regulator.... now how to test?

[Formerly Steve Wilkinson]

$500 for an alternator? Where can I get one? It must be gold-plated.

[jeffrey2]

Joe - any luck? I took mine out for a leisurely commute today and the alt light came on; the alt is only about 3 years (and 1000 miles) old; hoping that's not the case.