Alright, sometimes when i take the load off the engine (press clutch in) my voltmeter will drop to halfway between 13 and 8, doesn't happen when i'm moving, and when i put load back onto the engine or i rev it up, it rises again nice and fast. the alternator is less then 5 months old. i'm thinking its either my battery or theres not enough tension on the serp belt.

anyone have any ideas?

this just started happening about a month ago(when it started getting cold)

 

My 3.1 was doing that too. The voltage was fine when driving but dipped below 12 when at idle. I tried replacing the belt, and it didn't help any. About a month later the Alternator died.
If you bought a reman it could be going out on you again. I went through 3 remanufactured alternators on my Formula before I got one that lasted more than 6-7 months.

 

damn i was kinda hoping it was the battery not the alternator, it has i 1 year warranty but if it goes i'm gonna get a new one, did the new alternator fix the problem?

 

Yes. A new (rebuilt) Alternator fixed it.

 

if you're idling less than 600 rpm it can play a huge factor.

 

lol my cars kinda screwy i'm idling at 1300-1500 rpm

so thats not the problem

 

yep you need a new alternator. even if you had an under-drive pulley on the alt, you should still be making 14.4.

 

Do you have any other "power draws", like rear window defroster or front defroster with the fans on full? Is this when it's dark out?

It is NOT uncommon to see a power drop during winter when you have most of your accessories on while idling. I really noticed this when I installed smaller pullies too.

Also, the alternator you installed may have been a bit smaller than you should have installed. I prefer to install the highest amperage alternator available.

 

you also have to think, the alt doesn't make full 14volts until 2,000rpm, thats why it dips and your lights are dimmer at idle compared to crusing speed.

 

Where did you get that from?
Every car/truck/motorcycle I've ever had has made 14 volts at idle. I'm not talking about the reading on the gauge in the dash either. This is using a voltmeter. Yes, if you turn on all the electrical devices the reading will drop, but it still shouldn't drop below 12.5-13 volts.

 

this alternators been in for about 10 months now, never had a problem until a about a month and a half ago, i try not to draw any extra power(like rear defogger) unless i have to, its more common with the lights on, but it does happen during the day aswell.

i'm just gonna go out and get another alternator with a better warranty(this one was 1 year and the reciept got stolen) and higher output

 

I have a similar problem, when i turn on my turn signals, the voltage on the gauge, drops and fluctuates below 12. Some times it doesn't do it but it does it most of the time. Also some times when i start the car the voltage is reading low on the gauge.

I don't have anything that requires electriclity hooked up, just lights, ignition thats all.

Could the problem be the flasher or the alternator, voltage regulator. I don't really want to was my performance money on a new alt if i don't have to, thanks.

 

its most likely your alternator,these things do die, and its better to get a new one and be on the safe side, then to have it crap out on the side of the road and need a tow

 

I have a similar problem. Mine drops down to ~13v when at idle with the lights and defrost/heat on-(not the window). I notice a difference in the engine as well- runs rough. I lost two batteries because the car was running off of the battery at this level. I bought a new battery and now watch the voltage with a real voltmeter. It seems to drop on it's own but usually as described above.
I have the 2.8 as well, it must be a common problem with some kind of resolution. I have a "new alternator" when I bought the car. I'll have to pull the alt off of my F-41 to see if that makes a difference.

 

just because the alternator was new when you bought the car, doesn't mean its still good, as i said mines only 9-10 months old, and i'm gonna bet money that a new one fixes it.

 

How hot does your alternator get? I had one that did something like that most of the summer (although it didnt dip as low) and it got VERY hot to the touch... I swapped it out for another, and it was above 13V all the time and it never got as hot as the old alt did.

 

i've actually never felt it, i'll see tommorow

 

Thanks for the info.
I bet that could be an overheating problem.
I'll hang onto this until I can check this out. Besides, nothin's gonna overheat at -10 F. I'm letting my truck take the brunt of the salt this year as well.
I was told that the connector to the alternator can cause problems too. But I haven't been able to find a good one to try yet.

 

I've heard that too, but haven't had personal experience with that connector being bad.
Also make sure the alternator is grounded well. Clean off the outside of the bolt holes on the bracket. I've seen a bad ground do strange things.

 

I have also been told that cheap alternators do not have the charging capability at low RPMs that say a AC/Delco or other expensive name brands do. It is not all about more total amp output either. If you can't get the amps at low RPMs it doesn't matter how many you get at 2000-2500 RPMs. I know my next alternator will be a rebuilt AC/Delco.

 

have any of you had an alternator drain the battery overnight? i have unhooked everything except it from the battery and with a meter it still shows a drain until i take the hot wire off.

 

no the alternator won't drain a battery when the cars off, its some other power source.

 

It will if theres a short in there, or a resistor or some other electrical component doing odd things.

 

It will if the diodes in the rectifier are bad

 

Thanks, that's good advice, I should know that.


That's interesting about the alternators at idle speed.

As a note:
It seems like something unknown changes like a switch and then the engine runs rough (presumably due to it running off of the battery) the voltage drops from 14.5v to ~13v. If I rev the engine I get very little response in voltage. It seems to be random and have a mind of its own. This could be a ground or alternator issue.