Noise coming from accessory drive on engine (with video)

[gone_fishing]

I've owned my Sierra for over 5 years and 145,000 miles. I do most my own maintenance and feel I'm pretty in tune with the truck. Lately I've noticed an abnormal noise coming from the engine bay. I'm not sure if it's due to cold weather or just happen to begin when cold weather started. I took this video immediately after a cold start in my garage. Temp was around 38°F so cool but not really that cold. From what I can tell the sounds appears to be coming from the very front of the engine around the accessory drive. It's a little more noticeable on the driver side compared to the passenger side. Belts are all original but the vacuum pump was replaced in March. Sounds doesn't appear to be coming from that anyways. I'm wondering if it might be the belt tensioner? Belts look good but might be about time to replace them anyways.

 

 

Edited December 19, 2018 by gone_fishing

[B R A D]

My 1st guess would be the belt tensioner. I had one go bad on my Mustang and replaced all of the pulleys at the same time, wasn't that much more expensive.

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[diyer2]

Tensioner, idler pulley or?

Auto stethoscope will help find it.

 

[gone_fishing]

4 minutes ago, diyer2 said:

Tensioner, idler pulley or?

Auto stethoscope will help find it.

 

Forgot I had one of those! I'll listen to the tensioner through the stethoscope.

[Sierra Dan]

Could also be a water pump bearing.

[kickass audio]

Make sure all of the pulleys are tight and not loose from a worn bearing. To check the belt get some water and spray it on the belt. If it gets louder when you spray the flat side of the belt you have a tension issue, if it gets quieter when you spray the ribbed side of the belt you have an alignment issue. Your belts look a little old so maybe they are getting close to needing to be replaced.

 

Start the truck with the accessory belt removed but don't run the engine too long since you will have no alternator or water pump. If it goes away then you know your problem lies with something on that belt.

[gone_fishing]

Update: Removed the serpentine belt. Water pump and alternator felt normal. The tensioner pulley spun freely but had a little bit a "gritty" feel to it and noticed felt some slop. I decided to pickup a new tensioner (and belt since I had it off). After installing it does seem to be a little quieter. Will have the truck outside for the next few nights. If I don't hear anything after a cold start I know the tensioner was the problem. Thanks for the help!

[Strewn]

I have just taken in my 2921 Sierra, noticed a whining noise, they told me it was the idler pulley, was shocked that it was worn out after 12000 miles

[JimCost2014]

Sorry, just had to.

 

Amazed you were able to buy a truck from 900 years in the future, and most can't even order a 2021 or 2022