Yet more alternator problems?
 

I just replaced my alternator and today I was setting the timing and noticed that above 3500 rpm's the alternator light comes on. What could be causing this?

Mike

Is the belt slipping?

I checked the belt and its tight. I might make it tighter to see if it makes a difference. I cant hear it slipping but then again my gutted muffler is kinda loud!

Mike --

I'd suggests you check your grounds. Most of my most mysterious and irritating electrical issues have been a result of a bad ground.

T.

odd..usually if the light is going to come on, it's going to be at low rpms and if the brushes are wearing out, it takes a bunch of rpms to extinguish it. is the alternator internally or externally regulated? have you checked system voltage at various rpms?
ryan

the system is externally regulated. I haven't checked the voltage at dif. rpm's will do that later today. What are the symptoms of a bad external regulator?

well, the alternator puts out more than 14 amps...the regulator 'regulates' it down to 14. if it starts reading abnormally high voltages would be a sign. a digital meter is best for taking instantaneous readouts.
ryan

Mike,

Is the warning lamp full brightness, or perhaps only a half-bright glow? If the system Voltage is 13.2 - 14.5 Volts from idle to full rervs and the glow is only half-bright ... it isn't a real problem, just a phantom. Older electrical systems can develop Voltage drops at all of the connections due to corrosion and that causes the lamp to glow dimly. You can ignore it or clean every connection ... from all ground straps at alternator and regulator panel ... all connections at the alternator, regulator, 14-pin connector, and at the warning lamp Faston and bulb holder body!

hi warren :) is it just my imagination..doesn't seem like i've seen you posting as much in recent weeks? good to see you at any rate.
ryan

Thanks for the advice warren. It isn't glowing very bright. It just worries me to see it on!

I checked it again tonight in hte dark just because I wasn't 100% sure. The light does seem to come on light around 3300ish and and very bright at 3500+. Anyone know whats going on?

Mike

mike...did you ever check your system voltage with a voltmeter with the car running?
ryan

not yet, I need to go pick one up. Im only 18 and just started building my tool collection! Ill check it today.

Mike

okay..i understand that. you'll find they come in analog (just a moving needle) and digital form. try to get the digital model if you can..doesn't have to be the most expensive model either, but digital is more accurate and you'll find a use for it all the years you own cars. with the car running, if the cig lighter works that's a place you could hook up the leads or at the battery terminals themselves. with the car off, it should read around 12 volts at the vattery of course, but while running, expect it to read between 13.5 and 14.5 volts..that's where the voltage regulator 'regulates' your system voltage. if you can check it at various rpm's and at times goes much beyond this, i'd suspect regulator problems. some times people see 15, 16 volts..means a faulty regulator and can destroy a battery through overcharging it in the process. good luck!
ryan

Well I tested the battery today with VERY interesting results. I tried to start it up and the battery was dead. I charged the battery and started her up. She read 11.97 but slowly dropped in voltage about a hundreth of a volt every couple seconds and would then stop about every tenth of a volt. I decided to take her around the block and she died about halfway down my block. Obviously the new alternator I installed isn't charging the battery. The weird thing is the alternator light isn't on anymore. I am going to tear it down and triple check the alternator connections. Could it possibly be the external regulator? Im sooo sick of dealing with stupid electrical issues! I just want to drive!!!!

Still frustrated,

Mike

mike,
many on the board will change batteries every 2-3 years, just because it's 'cheap insurance'. if your battery is very weak, your alternator is not designed very well at to re-charge it..that's understating it. my advice (i'm assuming an old, weak battery with dead or dying cells) is to buy a new battery and see what happens. with the new battery, check system voltage while the car is running..that way you'll see what the voltage regulator is doing. it should regulate alternator output to 13.5 - 14.5 volts. if it's higher than that, say 16, 17 volts, i'd be suspicious of your regulator..and that could be the reason that the current battery is dead - it's been overcharged and in essence, 'burned up'. on the other hand, of the voltage is low, say 12 volts, i'd suspect your alternator..that would suggest that battery voltage alone is trying to power your system.
ryan

The more I think about it the more im suspecting the alternator. probably because I just replaced it. If there was a problem with the alternator wouldn't the light be on though?

Mike,

If you have to pull the alternator again check the grounding strap. It won't work without it attached. Maybe you can take the alternator in to a shop to test it, too. Let us know when you solve the problem.

Dave

where did you get the alternator? do you recall the brand, number of amps? did you do the installation? could be that the ground strap isn't tight..or maybe not connected? other wires not on the right posts?
ryan

Marchal 60 70 amp. I picked it up from a pelican. Had a rebuilt sticker onit from 05. I installed it... which im concluding was/is the problem. Ill check it out and keep you guys posted. thanks for the help bigchillcar

Mike