Hey, how's it going everyone.

My truck is making a squeaking/ chirping noise. I think it's either belts/ tensioner or drivetrain. But I think more likely drivetrain because it doesn't do it at all in neutral, only while driving and only under power, never when coasting.

It also doesnt do it when I'm on the brake and load up the driveline tension by giving it some gas.

It's a little intermittent but more so consistent. Sometimes it quiets down a bit but it happens every time I drive. It's been happening for about a week now and it's not going away or getting any better so I really want to figure it out.

Let me know any missing details and I will provide. Thanks in advance for any help or insight.

 

Mine turned out to be a combination of the bearing in the water pump, as well as a bad harmonic balancer.

Would only chirp regularly on acceleration.... Would totally stop when decelerating. Sometimes I would hear an occasional chirp at an idle.

Of course start by making sure your tensioner, idler pulley and serpentine belt are in good condition.

With it idling, look down at the harmonic balancer and see if it's wobbling at all. If it is, it needs replaced.

With the serpentine belt off, grab each side of the water pump fully and check for play. If you can detect any play in and out or sideways, time for a new water pump. Or if you spit a fast by hand and you can hear it squeak.

 

same advice as the water pump for the iders and tensioners. grab em , wiggle em, spin em. look for wobble, slack or play or grindy or loud bearings.

 

Thanks and that all makes perfect sense except this: "Or if you spit a fast by hand and you can hear it squeak." I didnt understand that last line?

Thanks, both you guys have been super helpful. These are the best ideas I've heard and I will definitely try these as soon as I can.

 

Lol, typical typo by Google voice. If you spin the water pump pulley by hand..... Give it a really fast turn.... If you hear it squeak, time to replace the water pump.

If you turn it slowly you won't hear anything....

But a chirping belt only on acceleration is usually the harmonic balancer or the tensioner pulley.... There's a lot of load on that belt when accelerating, compared to deceleration.

 

While you have your serpentine belt off, remove the AC belt and the dreaded tensioner.... Throw the tensioner away, and install a stretch belt like the later models use. AC Delco 4K355SF.

 

Thanks again Robert, for your help. My mechanic refuses to remove the tensioner or install a different belt and he is skeptical about the water pump and harmonic balancer as the cause. But we are planning to check them this week as you directed anyway. Since he does the work, I do have to go along with his advice even if I do push him a bit to try other things and every once in a while, I end up being right about the core issue. Hopefully this fixes it because the noise is completely annoying. It sounds like I'm driving around in The Jetsons mobile...

 

OEM GM harmonic balancers on LS engines are a known issue... You can probably Google it and find a hundred results.... Summit racing sells some really good aftermarket ones. (Such as the ATI brand)

The problem is in the thin rubber layer between the two pieces. The outer part with the pulley gets loose, causing the belt to squeak because it's wobbling.

The bad water pump bearing does the same thing.... Only takes about half a millimeter of slop in the bearing, and the belt will chirp in response.

The old style AC belt tensioner.... They don't tend to last long. It's a really small bearing that's spinning probably four times faster than the RPM of the engine. Pretty much why they abandoned it.....