Hi everyone! First time on this forum. Over the past few weeks my blazer has been making a strange noise coming from the dash area. I'm fairly certain it's coming from the engine though as it is rpm dependent. The sound normally goes away when my foot is off the gas. I have been able to stop it from coming back by pushing on the intake hoses a bit and adjusting them. I have always secured them correctly. And all of a sudden today I can't get it to stop. The video below is the best audio clip I could get of it. I'm pretty sure it isn't a major problem but it's sure driving me insane!
Edit: There aren't any cables on the pcv hoses, and the noise gets a lot quieter/basically goes away when idling for a while. Also, you cannot hear it if you're looking in the engine bay.

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Thanks!

 

Nobody?

 

Not a clue Dude, I have a bump over my dash area but haven't heard your sound. Sorry

 

It sounds like the problem is your throttle and/or cruise cables resting on the PCV vacuum line. This will transmit the noise of the PCV valve into the cables and then into the firewall resulting in what sounds like a plastic gear stripping it's teeth somewhere inside the dash.

I know you said that isn't the case, but that is exactly what it sounds like to me. Perhaps something is moving when you reinstall the intake ductwork?

You could troubleshoot this by finding a new PCV valve that is a fixed orifice design (i.e. no rattle) and see if swapping that in does away with the noise.

 

Thanks for the responses guys, the problem has actually escalated a lot since I posted. I got my blazer inspected yesterday and when I got home cylinder 1 started misfiring and now I can't drive it. I think I'm just going to take it to a trusted mechanic and have them take care of it.