What Are the Symptoms of a Bad Alternator, ...will the car run off the battery Options

[7TPorsh]

The other morning my car wouldn't crank; lights on dash but no juice. So I charge the battery up and start the car....drive around for a bit. Stop and start after half hour. OK

rive some more and get home...turn the car off and same thing; no juice. I take the battery to FLAPS who analyzes it and says it's bad....even though my meter says 12.5 volts.

I get a new battery and installl. Car starts and runs and I drive back to FLAPS to test system in the car. Master guru technician says machine says I need a new voltage regulator. Of course they don't car it so I drive back home.

i get in the DD and hunt down a new voltage regulator and put it in. Car start and drives...so i drive back to FLAPS. On the short drive there the car is running "on and off".

i make it there. the 2nd master guru technician hooks up the meter and I manage to barely get the car started and running but it shuts off. He tells me the same thing again, the voltage regulator is bad.

I say i changed the voltage regulator and he says no its the one in the alternator. (IMG:style_emoticons/default/blink.gif)

So I coast the car back towards home but couldn;t get it started...going to try again later.
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So does this sound like a bad alternator? Car cranks but wont fire. Always thought it would run off the battery if alt is bad. Please help.

[dangrouche]

here is the comprehensive thread involving the alternator. Also make sure the incandescent idiot light bulb at the instrument gauge is working. If you changed it to an LED, the voltage for an LED bulb does not trigger the charging circuit. Yes, the car does run on the battery, for an hour or less.

http://www.ratwell.com/technical/ChargingSystem.html

[injunmort]

car will start with 11 or so volts, will run down to 8 or so volts off battery. easiest way to check if you are charging, is start car and measure voltage across the battery poles. should be 12.5 to 13.5 volts. less than that you have a charging issue. voltage regulator, alternator, grounds all could be culprit. start with battery first.

[7TPorsh]

Car cranks but does not start now.

[colingreene]

Fuel air and spark, its one of those things.

[porschetub]

here is the comprehensive thread involving the alternator. Also make sure the incandescent idiot light bulb at the instrument gauge is working. If you changed it to an LED, the voltage for an LED bulb does not trigger the charging circuit. Yes, the car does run on the battery, for an hour or less.

http://www.ratwell.com/technical/ChargingSystem.html

Good call on that reply and (IMG:style_emoticons/default/agree.gif) or the other side is that it runs on the altenator until the revs drop then it dies,I don't know that much(lol) but really feel the OP has a bad altenator and is running on the battery because the brushes in his altenator are screwed or the commutator is carboned up.

[McMark]

Master guru technician says....
2nd master guru technician hooks up....

I say i changed the voltage regulator and he says no its the one in the alternator. (IMG:style_emoticons/default/blink.gif)

I hope you're using the term 'master guru' sarcastically. (IMG:style_emoticons/default/blink.gif) (IMG:style_emoticons/default/huh.gif) (IMG:style_emoticons/default/dry.gif)

While the car is running you should see 13.5+ volts at the battery. Battery cables are also a 'service item' and if yours are original may be part of the problem.

Charge the battery, start the car and test the running voltage.

[TheCabinetmaker]

Master guru tech at flaps. (IMG:style_emoticons/default/av-943.gif) (IMG:style_emoticons/default/av-943.gif) (IMG:style_emoticons/default/jerkit.gif)
The alternator has no internal regulator. Follow marks instructions.

[7TPorsh]

Yes, guys, master guru is sarcastic term. ....I did change the battery and the regulator. I can crank the engine but no spark. Everything else is relatively new: coil, distributor, etc.

Will it spark with a dead alternator?

[TheCabinetmaker]

Yes. You can remove the alternator and still run the engine. It charges battery and nothing else. So it cranks but no spark? This is an unrelated problem.

[McMark]

Yup. Curt is right. The alternator's only purpose in life is to charge the battery. It does nothing else. If it's not working, the battery voltage drops and you start getting problems, including no-crank or weak-crank. If it's cranking strong but not firing you have another problem.

Solve the spark issue, then confirm the charging voltage.

Do you have conventional points or electronic points?

[Toast]

The symptom is the generator light comes on. ;-)

You can get things like dim lights or slower starting. But usually it just goes out. I was able to drive all the way from Riverside to Jean Nevada on just the battery only before I finally didn't want to chance it the rest of the way. That's about a three and a half hour drive with headlights on.

Could possibly be the starter. If the alternator is getting weak your voltage will be lower. Its easier to test the alternator and the battery.

I can get a voltage regulator fairly cheap here in Vegas. Let me know if you need me to locate you one.

[7TPorsh]

I can't rely on the dash lights; not sure it's wired up correctly. I suppose fixing that too will be part of all this.

I managed to get the car running. Fuel pump fuse blew. Meter shows 11.4 volts with the engine off. i start the car....no change......bummer., time to jack the car up I guess.

Is the next step the alternator? Should I just replace it or is there anything else in the circuit?

[TheCabinetmaker]

Have you checked belt tension?

[7TPorsh]

Have you checked belt tension?

Thanks Curt, ya going to check the belt, wire connections, etc. I don't hear slippage and I dont recall sensing the belt break.

But going up on stands tonight.