Whistling noise

[WCBlueSky]

I sometimes get a loud whistling noise after I've been driving for a while. It sounds like it is in the dash, and at first I thought it was from the vents, but on the last trip it stopped making noise whenever I pushed on the brakes. So I'm thinking maybe a vacuum leak. Anyone ever have a similar issue, or have suggestions on where to look first?

 

[brettk]

Can you hear it in the engine bay as well as the cab?

My instant thought is the brake booster hose, but I just replaced mine and It didn’t sound anything like that.

 

[enox]

That's annoying

Does temperature have an affect?

 

[brockdeck]

Are all of your dash vents properly open?

 

[Bludozer]

I opened this thread ready to type that its the classic 80 exhaust whistle. Instead someone took a squeak toy shoved it into a microwave and turned it on in your truck

 

[Kernal]

Is the seatbelt warning light on while you're driving (seat belt on or off)??

 

[bicycleagent003]

I had a weird whistle for years. By luck, I realized it goes away when I put the front PS window down a hair, not even though to let rain in.
Maybe play with your windows a bit, one at a time.

 

[WCBlueSky]

Thanks for all the replies. Next time I get the noise I'll check in the engine bay and poke around in the dash.