Brakes

[MTChevy]

So I was thinking, I just picked up an 85C30CC.... When the engine is cold and i press on the brakes there is a few times when a hissing noise is heard, sounds like a vacuum leak from under the dash. Can anyone explain to me what this is? It still has normal braking when doing it and doesnt do it when its warmed up. It is a hydroboost system.

 

[neverendingproject]

Thats what hydroboost sounds like sometimes. There might be air in the system or the fact that its just cold. Mine does it sometimes.

 

[FlatBlackBurb]

yeah mine does that too... its onlywhen its cold and sometimes it doesnt even do it when its cold. but it always does it when the truck is off. when it warms up it works great