Is my alternator shot?

[mathd]

Well, just taken a 4 hour drive, and halfway trough the ride my voltage gauge went from 14v down to almost 9 volt.. sometime it went back to 14 volt for a few minute then back to about 10 volt(dim light), drove the truck for 2 hour like this... glad i made it home.
Also when i was at a stop light my tach was going completly down at the bottom(those model has the tach signal from the alternator)

The alternator is a CS-130 i think,
So what do you think? bad alternator or i should look for something else?

 

[grumpyvette]

carefully inspect, clean and re-attach, BOTH ends of your battery and ground cables and the main power cable to the starter, on some cars they can cause similar symtoms if the cable connections are corroded, but it sure sounds like the alternators shot, read the link

viewtopic.php?f=36&t=3222&p=8575&hilit=testing+alternator#p8575

If you have a belt slipping issue....you do realize they make dual v-belt belt alternator pulleys and 3 and 4 v- belt crank pulleys and 3 v belt groove water pump pulleys

https://store.alternatorparts.com/2-groove.aspx

just a point many guys seem to over look, the fans run on electricity and a higher amp capacity alternator provides a good deal more current to spin those cooling fans, charge the battery, and provide current to the lights , Ive seen several cars with marginal cooling that had that cooling issue disappear once a 160-200 amp alternator replaced the stock alternator, the increased current allowed the cooling fans to spin a good deal faster at low engine speeds and the result was more efficient cooling.

 

[mathd]

Just got it tested this morning, it was the alternator, charging at only about 12 volt.
I wanted to upgrade to a CS-144 but they didnt had one in stock so went with the stock cs-130/105 amp model.

 

[grumpyvette]

just a side note here, Ive been absolutely amazed at times at the difference in how cars run, when you upgrade to a larger more powerful alternator.

while all the factors were a bit hard to measure there was zero doubt that the ignition proved to run cleaner, plugs looked better and the electric cooling fans cooled better, which indicated to me that the stock alternator was marginal.

viewtopic.php?f=70&t=6964&p=22890&hilit=corvette+alternator#p22890

http://storesense1.mysuperpageshosting. ... &total=111

http://garage.grumpysperformance.co...that-some-guys-don-t-look-at-the-clues.11176/