Air Squeak on 70 series when braking

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Feb 28, 2005
Hey guys
I have a 1986 BJ70 and I get and squeak when the brake pedal is at a certain level of depression, sounds like the booster is letting pressure out into the cab and gives off a fairly loud squeal... Is this a sign of a bad booster? Braking performance hasn't been effected that I notice.

Any comments/direction would be appreciated!

I guess your brake warning light does not come on...
Does your brake warning light function correctly? There is a vacuum sensor/switch that registers not enough vacuum and turns the light on.
Since I installed a larger 2 diaphragm booster, my warning light comes on fairly frequently.
just today I started getting my idiot lights popping up... typically I would have to rev the engine about 2000 rpm to get the idiot lights to turn off on a cold start up, is that that vac sensor? Now it seems like it cycles on off, on off quite a lot... hot hot weather seems to make it worse... its the e brake light and the battery light beside it, I always figured it was a chargin relay or something
The brake light in the dash is wired to the e brake handle as well as the vacuum sensor/switch. I think it is also connected to the brake master cylinder.
Any of these can make the light come on.
what about the battery light that's the one comming on with the brake idiot light

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