Join Date: Feb 2006
Location: Boise, ID
Bronco Info: 1981 300ci 6cyl w/4bbl conversion. 4spd NP-435 manual. 32" tires.
Back to this.
Turns out my brake booster was bad (noise got progressively worse and the braking power was fading quickly) so I replaced it.
However, now, whenever I let off the brake, there's a slight air hissing noise. (I really only hear it when the engine's off because it's pretty quiet). Kinda like the sound you get when you have a pin prick hole in an air mattress. You can hear it, but you can't exactly tell where it's coming from.
If I press on the brake, it goes away. If I pull on the brake pedal with my foot, it goes away.
I don't think this is normal, but is it something I should worry about? If so, I'll take it back and swap it out under warranty, but don't want to mess with the whole ordeal if it's no big deal.
March 2016 FOTM
1981 Bronco. 300 I6. 450cfm QuickFuel 4bbl. BFG A/T KO2 32x11.5" tires. NP-435 trans. EFI exhaust manifolds. 2.5" Exhaust. DUI performance ignition. Redhead steering box.