320A alt dropping voltage

[wew lad 5,000+ posts]

i think the reason why some alternators do this is cooling. some vehicles like our chevy trucks idle low at around ~450 (cars are like 600-800 I've seen) and i dont think it cools the alternator enough to keep it on. I'd like to know for sure though.

when you put the belt on, was it tight? when i put my serp on my 5.3 it was tight as hell, i had to struggle to get every last bit of it on lol

 

[C1500martin 10+ year member]

Well i had to move the truck this morning and its maybe 63 degrees and its squeeling ALOT, my belt was toght but i was able to put it on with one hand while the other was puching the tensioner, so it wasnt THAT tight

 

[wew lad 5,000+ posts]

how old is the belt? might be glazed over and need a new belt. i bought a dayco belt or something from advancedauto and it was 100x better than my last belt (it was like 10 years old though). bad belt tentioners or bearings can also cause this, your truck is around the same age as mine and I've been told to look out for it.

 

[C1500martin 10+ year member]

Yea belt and tensioner are probably still from the 90s lol, i went to autozone to see if they have the tensioner and belt but ive had real nad luck with autozone parts so i just wemt to get part nulbers and ima see if i can find better parts online

 

[wew lad 5,000+ posts]

if you have an advanceauto there you can get the stuff pretty cheap, dayco has been a good brand for me. belt was like $20 and you can usually find a coupon online lol but you're on the complete opposite coast so idk if they have those there

 

[los33 10+ year member]

Yea belt and tensioner are probably still from the 90s lol, i went to autozone to see if they have the tensioner and belt but ive had real nad luck with autozone parts so i just wemt to get part nulbers and ima see if i can find better parts online

Replace the idler pulley, belt tensioner, and buy a goodyear gatorback belt.

Theres a chart you can cross reference stock belt size with it.

Sent from my Z970 using Tapatalk

 

[C1500martin 10+ year member]

Replace the idler pulley, belt tensioner, and buy a goodyear gatorback belt.
Theres a chart you can cross reference stock belt size with it.

Sent from my Z970 using Tapatalk

the belt tensioner comes with a new idler pulley if i buy the whole part together right?

my local auto zone has them and the day belts but is $50 for the belt tensioner and $35 for the dayco belt

 

[los33 10+ year member]

the belt tensioner comes with a new idler pulley if i buy the whole part together right? my local auto zone has them and the day belts but is $50 for the belt tensioner and $35 for the dayco belt

The belt tensioner and idler pulley are 2 different parts.

The tensioner should be like 30+$ and the idler pulley assembly should be 20-25$.

The gatorback belt can be bought on ebay for 25$ and it is known as the best non slip belt made.

 

[wew lad 5,000+ posts]

you should be able to find coupons, i only paid like 12$ for my belt from my local auto parts store. shop around maybe. id start by just changing the belt if the old one looks like crap and see what that does. no point in throwing an idler pulley at it unless you know its bad.

 

[fatboytyler]

Whats your RPM at when idle? I have this issue with my Singer 6 Phase and after much troubleshooting and talking to Mike we've come to the conclusion that my truck idle RPM is too low to keep the regulator active. So I am anywhere from 12.4 - 13.6ish at idle (only when in drive, my park RPM is fine). Shouldn't be an issue, but my truck is also 16 years old with exhaust leaks left and right. So I'd check and make sure your RPM while hot idling in drive is enough to fire the regulator.

 

[C1500martin 10+ year member]

Truck doesnt have a tachometer so isk what my idle speed is, but that sounds like it could be it, low rpms although my teuck being a 6 is noisy as hell

 

[r0llinlacs 10+ year member]

Put a smaller pulley on the alt???

I don't have a HO alt but I had a brownout problem where voltage would drop to 12 at idle/stopped/in gear. I grounded the battery with 0 gauge and somehow fixed it 90% of the time. Didn't expect it to fix that but I won't complain.

But it just sounds like either your engine is idling too low (something wrong with it) or the alt just needs a smaller pulley to keep up at low idle speeds.

If your batteries are junk that could be the problem too, or a bad connection which was the problem in my case, a bad ground.