Squealing Noise Near Firewall [Archive] - Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum

: Squealing Noise Near Firewall

03-02-2013, 02:25 PM
I own a 2005 GMC Envoy XL SLT 5.3L V8

I have had a loud squealing noise for a couple weeks now. The noise sounds like a metal on metal squeal of some sort. I can not find the exact location where this noise is originating from, but it squeals loudly the worst when starting vehicle as well as when I put the vehicle into gear and start slowly moving. Within the last couple days the noise has started to squeal when revving the motor regardless whether or not the vehicle is in park or in gear moving.

I replaced all pulleys, tensioner assemblies, and belts. However the noise is definitely not even coming from the front side of the motor. It sounds as if the noise is coming from somewhere near the firewall, or even farther back on the vehicle. The fact that the squeal is happening when starting the Envoy, revving the motor in park, and when the vehicle is in gear and moving really has me confused as to what it could possibly be???

My Envoy is displaying no other symptoms other than this loud screeching metal noise.

Can someone please help me out with any possible ideas as to what may be causing this?? It seems like there are a lot of people on here that are extremely knowledgeable when it comes to issues like this, someone please save me!!:thx

03-02-2013, 03:21 PM
Someone please help me!!!!!!

Jewel red 5
03-03-2013, 12:02 AM
Take off the fan belt and start it for a min or so it
Will rule out fan clutch,alt,pwr steer, water pump then remove small belt to rule out ac comp.if you still have noise then you know it's internal or even a vac leak check seal on brake booster the rubber drys out and cause a whistle noise. Good luck.

03-03-2013, 08:10 PM
Thank you for the reply!!

When I changed the serpentine and AC belts, idler pulley & both tensioner pulleys I had done that check just to make sure I didn't need to replace anything else that was belt driven. Noise is definitely not coming from that area or any of those parts.

Today the noise lasted a little longer than normal, and I was able to hop out of my Envoy and try to locate where this noise was coming from exactly. I was able to pinpoint the general area as to where the noise is coming from. It is coming from the right side of vehicle near or even a little behind the firewall, but definitely behind the motor!

Until I put it on my lift I won't know for sure, but I am thinking it is a heat shield rattle or exhaust issue of some sort. Maybe a loose bolt/nut?? Has anyone ever had an issue with a rattling/squealing noise in this area of your vehicle?? If so, would greatly appreciate some advice!!

Just hoping I am right and the noise is coming from behind the motor and not from internally in the motor!!!!!!!!!

Any suggestions would be GREATLY appreciated!!!

Thank you!!!

03-03-2013, 08:17 PM
Not sure if this could be it, but I had a noise coming from the area you are talking. It was the catalytic converter. Just a thought.