Ph34r

I looked and searched but could find nothing that addresses my question.

I recently replaced my alternator and discovered a host of new problems after I did so.

#1: When the engine gets to operating temp the output of the alternator goes to ****. Main problem here is when I drive at night. With the headlights on the voltage drops to 6-8 at idle and the lights dim and when I am at higher revs the voltage goes back up to 13-14. But when the car is not at operating temp this problem does not exist, I started the car cold and turned all the lights, AC, radio on and even opened the sunroof and never got that bad of a voltage hit. I have checked ground and even ran new grounds from the Strut towers, engine and firewall to the neg post on the battery.

#2: The car will, after sitting for a while, have trouble starting. I will crank it and it will sound like the battery is dead... but then if I hold the key it will slowly get faster and faster until the car will start.


Help?

Jason

satch

iTrader: (1)

When the voltage output of the alternator drops check the output at the alternator to see if perhaps the problem is the gauge or not. To measure the voltage from the alternator touch the B+ terminal (single Black wire bolted to the side) of the alternator with the red meter lead and the black meter lead to the negative battery terminal.

Ph34r

I am pretty sure it is not the gauge. It will turn off my radio and dim every light in the car when it happens.

But i'll check tonight to make sure.

satch

iTrader: (1)

Also, pull the two wire plug off the back of the alternator and w/key to on check for battery voltage on the Black/White wire. Then place the plug back onto the alternator and w/key to on ***** the White/Black wire with a pin and see if the pin has 1 to 3 volts on it. When you turn the key to on and the engine off do the idiot lights turn on? Do they turn off when the car is started? Do these lights ever turn on when the gauge shows a sizeable drop in voltage?

Read through the info provided in the link and do as suggested with regards to the voltage drop test.

http://www.aa1car.com/library/charging_checks.htm

In addition you might want to do this test as well which was taken from a fellow board member named "HAILERS."

"Or you can start the engine up. Put the pos lead on the output of the alt and the neg lead on the Case of the alternator. Put it on A/C volts and rev to around three grand with the headlights on. The A/C shouldn't be over a half volt when you do that. Actually should be a lot lower. That gives you a clue if the diodes are good/bad."

Ph34r

I'll do all of that, but the whole cluster lights up when the car gets to idle revs (850).

After it revs to about 2.5k they go away. But I do hear a faint buzzing from behind the driver side dash that goes away when the cluster lights up.

satch

iTrader: (1)

Napa makes the best off the shelf alternators while many of the other offerings are garbage/hit or miss quality. Appears you need a different alternator. The W/B wire should not be putting out a low voltage when the car is running unless the alternator has issues, which then causes the idiot lights to turn on.

If the B/W wire has voltage w/key to on and is plugged in properly then your problem likely lies within the alternator be it the regulator and or diodes.

RotaryRocket88

iTrader: (7)

Definitely sounds like voltage regulator trouble. At low engine speeds the alternator will struggle to put out enough current, but once you rev it up it will be decent.

And when it comes to replacement alternators, I've found the same thing that satch mentioned: stay away from anything other than OEM or NAPA reman alternators. I've had 2 from Kragen that were DOA right out of the box.

Ph34r

I actually got referred to a local shop that rebuilds alternators. I plan to take and have him wind it to a higher amperage. At least I can cross that off my list of "**** that I have to figure out"

Thanks again for all the help. I'll post up when I get another alternator and give the verdict.

Jason

ericgrau

iTrader: (1)

Most auto parts stores will test the alternator and battery for free, and it's usually one of those. Sometimes problems that come and go won't show up on the tests though. Sounds like the battery is bad at least if it has trouble starting, or else there's a short in the alternator. See if it has trouble starting when you disconnect the alternator.

Ph34r

Figured I would update this for the rest of the people who may be having this problem. Turns out it was a multi-stage issue.

The previous owner ran a new ground to the starter bypassing the strut tower ground point... and there were several points that had corroded over.

This caused the alternator to go south in a hurry.

I followed this guide and replaced the alternator... everything works like a charm now.