So, yesterday I changed my serpentine belt. Everything went smoothly. I started it up after to test it and it was nice a quite just like a new belt should be. I drove the truck several times today and it sounded perfect. Then...

This afternoon I changed my oil. Immediately following the oil change the truck makes a horrible sound at start up. I mean it was so bad that my first thought was that I forgot to put the oil in and the engine was seizing up. But, I checked and oil level and pressure are fine.

But, the horrible squealing sound at start up remains! How were things fine yesterday and today before the oil change and now this? The sound goes away like 2 seconds after I start the truck, but it sounds horrible. I had this belt spray lying around that you're supposed to spray on the belt to make the sound go away. It worked right after I used it, but now, the sound is back again. There were a few times today when it started without the noise, but it mostly still makes the horrible squealing noise when I start it.

Did I get oil on the belt? Would that make the noise? I was thinking this because it was fine pre-oil change. Or, has my oxidized old automatic tensioner gone bad? The truck didn't make this noise before, so naturally I'm concerned I fouled something up.

Please help!
pf

 

my guess is you have a semi-seized pulley of some sort...i'd take the belt back off and check to make sure all your pulleys spin freely.

 

Sounds like the tensioner pulley or the tensioner itself. Remove the belt and check all pulleys like wjxavier said. And while the belt is off make sure the tensioner travels to it's full tightening direction. And make sure the belt has the same amount of ribs on it as the pulleys have grooves .

 

I just checked all the pulleys and the only one that does not spin is the way bottom one, but that shouldn't spin right? I mean isn't that connected to the engine crankshaft, making it not spin freely?

 

yes...next i would suggest if you have a wife or someone else that can start the truck, have them start the truck, and see if you can pinpoint EXACTLY where the noise is coming from. do you think maybe your a/c is left on before you start it, and then when you start it, the clutch might be going bad and is squealing for a couple seconds? idk just a random thought.

 

Pulleys may have turned, but were they smooth with no roughness>

 

I'm thinking it's not the A/C because the truck's AC is broken (at least no cold air comes out). And that pulley spins fine too. This sucks. Truck might have been better off with old a$$ oil and a beaten up belt.

 

like i said, i would suggest you having someone else in the cab to start it, and you near the engine to pin point exactly where the noise is coming from.

 

Just because they spin fine, doesn't mean they are good. You have to check how much they wobble. And did you see if the tensioner arm travels fully? It needs to travel farther than just barely tightening the belt.

 

Okay, I examined all the pulleys again, and the water pump pulley (a smooth one) has some black hard gunk on it in some spots. For the most part I can scrape it off with my finger nail. Can this cause this noise? What's a good way to clean it off without damaging the pulley?

Ya, I checked the tensioner again. I mean it seems to be traveling to it's extent in both directions...and it takes a good amount of leverage to get it to turn clockwise. But then again, I'm new to this, so I have nothing to compare it to.