Forcefed86

iTrader: (4)

Using a 98 LS1 alternator thats about 2 years old now. Factory diameter pulleys.

Recently looking at my logs it looks like my voltage drops from a steady 13.9 to 12.5 or less above 5800 rpm? This a sign of a alternator that is about to go? Or possible belt slip? This common at all?

I've had alternators just quit, but never seen one drop voltage at RPM and then pick right back up again at idle and lower RPM?

conan

iTrader: (5)

Could be the voltage regulator going out. I had a alternator that would do the opposite, it would hit 19v at 5,500 rpm and hold 14v in the 2-3K rpm range.

Redbull87

iTrader: (3)

2 things that could cause this and i experienced both.The belt would slip at high rpm and not spin the alt enough,this was a combo of a weak tensioner for me and a old worn out belt.And 2nd is the alt itself was failing on the regulator as mentioned above. Check the easy things first and then have the alt checked.I upgraded to a truck alt at the sametime for the fact of the higher amperage needs on my car.

Forcefed86

iTrader: (4)

Thanks. Put a new belt and tensioner on it this week. Still doing same thing at track. Drops to 12v during a pass. Pops right back up to 13.4 after. Looked at old data logs and it held 13.4 steady the whole run. THink it has to be the alternator itself.