how do I check for a bad alt????

 

Chilton... haynes.... those should help. If for some reason it's not blatently obvious, you can check continuity through the plug and make sure it's not an inductive short in the alt. If you aren't real sure about working on your car.. take it to the "Wrecker Auto Parts" and have them check the battery first before you run out and buy a new alt. Good Luck.


Modified by delslo26 at 11:01 AM 6/28/2003

 

you can also have it checked at a parts store, but you have to remove it..which sucks ***** to do.

 

Put a voltmeter on the battery and have someone hit the gas it should go up a little and be around 13.6-15v

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 95excoupe &raquo;</TD></TR><TR><TD CLASS="quote">Put a voltmeter on the battery and have someone hit the gas it should go up a little and be around 13.6-15v</TD></TR></TABLE>

You shouldn't even have to hit the gas... Test battery voltage with the car off. It should be 12.50+/- volts. When the car is on, the voltage should be higher... 13 or 14 volts. If the voltage doesn't go up, you have a bad alt.

 

unhook the battery while car is running.

 

Just take it to AutoZone or something unless you have a voltometer sitting around.

Those things are great.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Mikey &raquo;</TD></TR><TR><TD CLASS="quote">

You shouldn't even have to hit the gas... Test battery voltage with the car off. It should be 12.50+/- volts. When the car is on, the voltage should be higher... 13 or 14 volts. If the voltage doesn't go up, you have a bad alt.</TD></TR></TABLE>

he's right, i did the same thing and its reall easy...it could also be that you have a bad battery.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Caveman74 &raquo;</TD></TR><TR><TD CLASS="quote">unhook the battery while car is running.</TD></TR></TABLE>this is the best way for a DIY'er to test it. take off the negative terminal from the battery...if the car dies quickly, the alt is bad...if it is good, then it should remain running.

 

Don't listen to this crap about pulling off a battery cable, that is a real quick way to cause more damage than may already be there. If you have a dvom, with the engine off get a baseline voltage reading from your battery 12.5 is 75% charged (this is a minimum) and 12.7 volts would be 100% charged. Then start your engine with no loads on and check the voltage again at the battery, this is your base voltage. Once you have done the base voltage test, you can go on to the charging voltage test. Start your engine have someone hold your rpm's between 1800 and 2000 and turn on all your loads ie. wipers,a/c,radio,headlights etc. Then measure your voltage at the battery again, if it is within 0.5 volts from your base reading then the alternator is good.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by panman41 &raquo;</TD></TR><TR><TD CLASS="quote">Don't listen to this crap about pulling off a battery cable, that is a real quick way to cause more damage than may already be there. If you have a dvom, with the engine off get a baseline voltage reading from your battery 12.5 is 75% charged (this is a minimum) and 12.7 volts would be 100% charged. Then start your engine with no loads on and check the voltage again at the battery, this is your base voltage. Once you have done the base voltage test, you can go on to the charging voltage test. Start your engine have someone hold your rpm's between 1800 and 2000 and turn on all your loads ie. wipers,a/c,radio,headlights etc. Then measure your voltage at the battery again, if it is within 0.5 volts from your base reading then the alternator is good.</TD></TR></TABLE>

thats the only way less doing a load test on it with a VAT style machine.
dont know what VAT stands for but it is the standard machine that checks that.
you can have 14 volts at the batt. if there isnt enough amps goin back to the batt, it will not charge.

 

You are 100% correct...What I described is only a voltage test I figured that would be a good start and I was not sure if he had a load tester. With a load tester and a dvom you can test voltage and amperage.