Vannin' Community and Forums Forums Chevy Troubleshooting Rattling Noise

Hello,

I hate posting stuff like this, as I know all too well how difficult it is to diagnose mechanical problems without seeing it first hand. But, my van has developed some sort of rattle, I'm thinking it's coming from the alternator pulley but am not sure. I know some of you guys know these vans inside and out, what do you think? I already brought it to a mechanic a while back, he said it might be the flywheel and said don't worry about it....which sounds kind of dumb. I'm thinking maybe the alternator pulley?

Video of the rattle

I appreciate any insight. The sound in the video came out fairly well when played on my PC, but on my phone it was really distorted, not sure why that is.

edit: Van is 1994 Chevrolet g20 5.7l

May be a water pump ... yes alt and or air pulley .. deff a bad sound ... time for some maintenance .


put a broom stick to it and your ear your will find out quickly which one it is ....

After watching the vid my first thought is a bad tensioner because they'll tend to rattle like that when they go bad, but I didn't see it moving around.

I'm thinking I just might replace all the pulleys I can get easily, any ideas of a good place to get them besides locally? Those pulleys are pushing 300k miles, wouldn't be a bad idea even if some are still good.

I bought this for my 93 from Rock Auto. I had to replace the alternator so I figured while I had everything apart.....

https://www.rockauto.com/en/moreinfo.php?pk=9117636&cc=1046719&jsn=887&jsn=887

I thought the exact same thing, but since it wasn't shaking, I didn't offer a guess.
Looks like we were on the same page.

Thanks for the info, gonna change it all out this weekend.

Just in case someone with a similar problem stumbles upon this thread, it's definitely the tensioner causing the noise. I was thinking maybe water pump, but I got a mechanics stethoscope, and it's definitely the tensioner, the water pump is not making a sound. I'm unsure exactly how a tensioner is constructed, so I cannot fathom how it is making that kind of noise. But, you can see the alternator and the tensioner very, very slightly shift when it's running, and it coincides with the knocking noise.

Happy you found it. And indeed, some use a big screwdriver and personally I finally invested in a stethoscope ( a few bucks ) which really help. They amplify the sound and mine also has an extension.