03 Trailblazer making odd noise when engine is reved up

[Jim Uran]

I have no idea where to begin looking, well I know I'll bring it to a shop. But, when i start it up it has a wierd growl to it, I can tap the gas and once it starts going up in RPM's it's like a little snore or a growl that wasn't there before. I can fell extra vibration also. And when I turn the key off and the engine shuts down you can also hear it give out a growl before it completely shuts off. This happens in gear and in park or neutral. I don't really notice anything or hear anything while going down the highway. ANY IDEAS or has anyone ever experienced this before.

[Scott K]

I would check the fan clutch

[Jeremy airjer W]

The fan clutches are pretty common. Does it sound like you are accelerating really hard even though your just idling? Be prepared for a little sticker shock when you see the price tag of that bad boy!

[Shack]

Does it sound like a big woooosh air noise noise?

Could be the clutch fan.

Do you have your setting's on defrost? If so shut the heater/AC control head all the way off and see if noise goes away.

[Jeremy airjer W]

Its that electronically controlled fan clutch assembly deal. When they go bad it typically doesn't matter whats on or off

[Shack]

Sorry Airjer, with my last question I was ruling out a possibility of a bad a/c comp.

But, would having the A/C on cause it to electrically engaged?

[Jeremy airjer W]

I don't remember specifically when it is activated or not. Good thought on the A/C compressor! I guess I was thinking the common problem without even thinking of the other possibilities. Typically they will stay engaged all the time when they go bad. Theres something about unplugging it and running the vehicle at a certain RPM for x amount of minutes if it doesn't deactivate then it gets replaced. They have all been replaced!

[Jim Uran]

Thanks guys, Airjer, no it doesn't sound like i'm accelerating really fast when I'm idling, it only makes the noise when I just slightly tap on the gas. That initial tap makes a little like almost a hole in my exhaust noise, but with some vibration. I turned everything off so I could hear it. It's really not that noticeable, but I drive it everyday and I could notice it. And like I said before also, when I shut it off it'll make that noise before the engine completely stops.

[Scott K]

One thing you can do is remove the serp belt, to eliminate anything like fan ac, ps, ect.. Since it sounds like exhaust it is possible you have a cracked exhaust manifold, or a emmision tube, or egr leaking.