Alright, second question, and I am looking for answers other than "Tighten the belt, idiot!"

After I start the car, the alternator does not produce any output until I rev it over 5000rpm. I can drive all I want under 5000, and the voltage just gets lower and lower. Once I rev past 5000, the volts jump up to 13, and stay there until I turn the car off.

What could be causing this? I will accept answers that explain why a belt may start turning the alternator properly above 5000 and not below, but "Tighten the belt, idiot!" is still out.

Thanks for the help. The winner will be sent my congratulations, and, if they are canadian, a certificate for $1000 off their next GM vehicle.

 

Nah, I think I'm gonna answer this one first and then move onto #1...

Anywhoozer, how new is the alternator. Could be bad... I've had em so that they don't produce much usable power till high RPM...

Also what year GSL did you put the SE engine into?

I believe earlier cars had an external voltage regulator. Later cars have them internal to the alternator. Running two voltage regulators might mess with things.

 

1985 chassis with a 1984 engine.

 

I agree with Pele.The voltage regulator is acting up.
The coils inside start to charge @ low rpm allready (900 if i remember correctly).The regulator is suppose to supply it with a switch on voltage; for the diode bridge to be activated.The diode bridge then converts it to dc.

These days the regulator and bridge are a integrated unit.

Karis

 

yup,

this seems to be field current/diode related. I'll continue to think of alternators as black boxes and have it rebuilt.

 

Some people still think of ignitors as black boxes or brain boxes. lol

 

I'm having the exact same problem with mine. Changed out the alternator and bought a new battery and its still happening.

 

Second the regulator is dead. For one thing, you should be seeing 14-15 volts not 13...

 

14-15? NO. Anything above 12.5 is charging but you should be sitting between 13-13.5 on a properly charging system.

 

one word buddy, WRONG!

14-15 is what is supposed to be on a properly charging system

 

but anything over 12.5 is "okay"

 

WRONG

 

shheeesshh! Never thought charging rate would be such a heated discussion!
hahaha!
Karis

 

Darnit! This is all George Bush's fault!

 

"If the voltage produced by the alternator goes above 13.5 - 14.5 volts, the battery will be ruined very quickly. It's the job of the voltage regulator to keep the output voltage between the 13.5 - 14.5 volt range."

http://autorepair.about.com/cs/elect.../aa122700a.htm

So we're both right. Go check your charging system on your car and tell me how many volts your actually putting out.

 

Wow, all this talk about how inacurate the gauges are in Hardcore Technical Question, and the fact that I glanced at my gauge and read 13 volts almost causes a riot!

Anywho, worse of 2 alternators is in getting rebuilt, 5000rpm alternator is in the car now, and I am getting the temp probe tonight for investigation purposes.

 

The voltage is temperature-sensitive. When it's hot out (think Arizona in August) then you'll be seeing low 14's maybe high 13's to prevent from cooking the battery. Conversely you can see as high as 15-15.3 in the cold (think Minnesota in February).

So: 14-15 volts.

 

you guys are lucky I drop to 10 volts at idle lol