[SOLVED] Underhood Intermittent Screech In Freezing weather

[marktrafton]

I have never had any issue with a .5 to 1 second spray of WD-40 cause any issues with a fan belt.

 

[B-train]

I have never had any issue with a .5 to 1 second spray of WD-40 cause any issues with a fan belt.

Silicone spray works as well and doesn't leave an oily residue.

 

[OR VietVet]

I have never had any issue with a .5 to 1 second spray of WD-40 cause any issues with a fan belt.

Silicone spray works as well and doesn't leave an oily residue.

Used both many times. The spray stem nozzles allows very pointed and precise amounts of spray.

 

[EddieC]

As a side note, since our ac has quit a few years ago, is it ok to leave that belt off permanently?

 

[OR VietVet]

Yes.

Besides having no a/c, it will no longer cycle when defrost is on, to help remove moisture in the interior air.

 

[Ghoff]

I recently have has a screech that seems on the left front side of our (5.3) engine (2008 Tahoe) when the weather temperature is 20 degrees and lower.
After a certain rpm, perhaps 2000 to 2500, it goes away but effeminately varies with the rpms and comes back when the revs drop but is mostly gone at idle.
It seems like it might be the PS pump or alternator but on a few tries it's tough to pin down.
There does not seem to be an uncharacteristic odor and the alternator seems to be functioning normally based on the instrument panel gage and the state of the battery. The power steering is functional and there is fluid in the reservoir.
Both drive belt tensioners were replaced with oem last year as were the belts.
Also there are no coolant leaks at the water pump and the temperature gage is running normal.

Any thoughts on which might be more likely to make the screeching noise if failing?

I saw an online clip that showed the alternator on some GM vehicles have a decoupler pulley which can screech if it is going bad. May want to google that and see if the symptoms are familiar.

 

[B-train]

I saw an online clip that showed the alternator on some GM vehicles have a decoupler pulley which can screech if it is going bad. May want to google that and see if the symptoms are familiar.

I have never seen such system on any GM vehicle. Post the video link if you have it.

 

[EddieC]

Thanks for all the input guys.
Simplest solution is the one. I can't believe how sounds travels because I was sure it was from the alternator/PS pump area but then maybe the throttle body.
It turned out to be the AC system. It has not worked in quite a while but the tensioner was changed with the belts last year with an oem replacement so if I count out the tensioner then that leaves the compressor. I can't get under there at the moment to play with the two things but could get the belt off from above and noise is gone.
It is amazing how the sound traveled.
Thanks again. Much knowledge acquired.

 

[Scrappycrow]

I have never seen such system on any GM vehicle. Post the video link if you have it.

These aren't videos, but:

1) They've been standard on Corvettes since '01, so they've been on GM vehicles for at least a quarter century: https://www.corvetteforum.com/forums/c5-tech/2607028-c5-alternator-decoupler-pulleys.html

2) They're on GMT K2XXs: https://www.tahoeyukonforum.com/threads/decoupler-pulley.152924/

Are they on any GMT900s? I dunno, the above is enough to show they are indeed on GM vehicles and have been for a while.