need help with alternator problem

Have a 1986 DL240. It will not charge the battery. Have bought new alternator, test light shows power going to the batter but still isnt charging the battery. Anyone have any suggestions on the problem and how to fix it.

thank you
Paul

Things to check- (1) voltage across battery should be at least 12volts without motor running. (2) battery terminals should be super clean (3) pos/neg cables should be in good shape & clean (4) the alternator should be producing almost 14volts with motor running...test light not a reliable check for this,you must use a voltmeter. (5) the battery my be faulty...internal short, plate breakdown etc...this kind of a problem is a pain. Best solution is to drop by a good parts store you trust and have them do a load test on your battery. Good luck

Hi.
Just had this problem with a rebuilt alternator. Turns out no charging was due to a loose earth wire, so check your connections.

1987 240 DL wagon. I have gone throuigh 4 batteries in 8 weeks.
Alternator has been removed and tested good, New voltage regulator installed. All of the wire connection have been cleaned and appear to be tight, I have conectivity through the wire from the alt to starter and from the starter to the battery.
Voltmeter shows 14 at alternator and 13.5-13.6 at the battery with car running.
The car runs about 4 days then it won't start, the battery is dead and the first three checked out at the auto parts store as being bad wouldn't hold a charge anymore. I'm about to return my 4th battery.
Any suggestions as to what else could be destoying these batteries? :banghead:

1987 240 DL wagon. I have gone throuigh 4 batteries in 8 weeks.
Alternator has been removed and tested good, New voltage regulator installed. All of the wire connection have been cleaned and appear to be tight, I have conectivity through the wire from the alt to starter and from the starter to the battery.
Voltmeter shows 14 at alternator and 13.5-13.6 at the battery with car running.
The car runs about 4 days then it won't start, the battery is dead and the first three checked out at the auto parts store as being bad wouldn't hold a charge anymore. I'm about to return my 4th battery.
Any suggestions as to what else could be destoying these batteries? :banghead:

You may be having something discharging your battery when it sits...
Look here for some testing notes.
http://www.brickboard.com/FAQ/700-900/ElectricalStarting.htm#SlowBatteryDischarge

i had the same problem I repalce 3 alternators and I end up replacing my crank shaft pulley, was separated in the middle after that the car was perfect,no more problems with the charging system was pain in the butt but now is ok

Make sure your alternator is grounded

Make sure a ground wire is not broken going to your alternator case--MIKE

how do you know there is electricity coming from the alternator unless you removed the terminals from the battery while it is running?

how do you know there is electricity coming from the alternator unless you removed the terminals from the battery while it is running?
With a voltmeter. Read battery with car off. Run the car and read voltage. Should be around13-14.5. If the readings are the same, suspect alternator or associated wiring.

With a voltmeter. Read battery with car off. Run the car and read voltage. Should be around13-14.5. If the readings are the same, suspect alternator or associated wiring.

what if anything is wrong with removing the battery terminal once the car is started. I can tell you from experience that the car will behave normally unless it is shut off,and it is indisputable proof that the alternator is functioning.

what if anything is wrong with removing the battery terminal once the car is started. I can tell you from experience that the car will behave normally unless it is shut off,and it is indisputable proof that the alternator is functioning.

I do know people who do it that way. But I also know folks who's computer got fried. I'll stick with the voltmeter..

I do know people who do it that way. But I also know folks who's computer got fried. I'll stick with the voltmeter..


Never heard of somone frying their computer that way, It's common practice in all the shops I've seen. It's not like computers are exspensive for these anyways, you can get them on ebay for like 50 bucks.


Not knocking the voltmeter method, I do that in addition to the other test.