Driving home from work today and the 105 amp alternator kicked the bucket. Barley got to parts store and upgraded to 145 amp in o'rileys parking lot. ('03 silverado 5.3). Now i didnt change the belt to the bigger one, using the little smaller factor belt. Battery checked good. Now while driving its at a constant 14v til i let out a lil bit and goes to under 12. Only does it in gear. Im wondering if the smaller belt is causing more drag from tensioner being close to maxed or if something else to check.

 

i swapped to 145 on mine, too, but the stock belt wouldn't fit. i put a longer one on & ain't had a problem out of it since.

 

What YMM did you give them to get the 145?

 

mine was a cross-referenced option at autozone: i believe 01 tahoe 5.3 rung it up.
and it was a few bucks less than a 105 w/ same lifetime warranty

 

The belt is 3/4" difference. Not sure if the tensioner compensates that evenly. Is there any reason to not just put the correct belt on and see if it fixes it?

 

Yeah im gonna buy one today. I was just seeing if maybe someone else had ran into the the issue before and then did X,Y,Z and the problem was fixed. Im about positive thats it thought. The tensioner was no where near as tight before and now its close to maxed out. Im gonna try it and the big 3 today. Thanks everyone.

 

Although you have the wrong belt, it will not cause a low voltage issue. The old belt is probably stretched enough that you were able to get it to just barely fit. As mentioned you should run the correct belt so that you don't put added stress on the bearings of the drive system.

You really can't use the gauge as an accurate way to measure the voltage.
Check it with a meter at the battery and verify, it should not drop below 12V while running.
With vehicle in park, turn on the AC, The radio, and The headlamps and interior lamps to load the electrical system and see if drops below 12 volts.

Sometimes the crappy rebuilds with Chinese parts don't work correctly.

 

Yeah, it doesnt drop below 12v but I also believe the gauge. You can feel it droping voltage. Do you recommend i return it for another one? I bought a reman because i literally had $160 in my truck and didnt have my debit card and was broke down. The reman with tax was 159 thank god. Im going to try the belt here shortly because the tensioner is damn near maxed and im think maybe with deflection with the ac on itsjust bogging it down. If that doesmt work im going to return it. Thanks guys.

 

How would the belt be stretched out enough, that when he just added the larger pulley to it, the belt would be ok? (I really don't understand it, but) the belt is only "stretched" from normal use at the correct length. Now the larger pulley is causing the belt to be 3/4" shorter. Wouldn't any stretch be picked up by the tensioner, and then still be too short with the new/larger alt pulley? Does a belt really stretch out 3/4" from normal use?

 

Well, just to update i replaced the belt wih the appropriate one. Drove around for awhile last night and the problem never came back. Had a slight scare thought. Put the belt on, checked all the way around to make sure it was seated in the groves. Go to start the truck and noticed it was running funny, rev it a few times and it stumbles bad and dies. I start think about it and remember i didnt put the intake back on so its getting unmetered air. Also, i went to do the BIG3 and cant find my crimp ring for them so ordering them tonight along with another 10ft of skyhigh audio 0 gauge.