Why does it sound like air escaping when brakes applied in my 1998 chev k2500?

SOURCE: hydro boost

Hi,

Appreciate the "Ask Me" and my compliments, scary driving one of those in our roads.

Might you have to check the Brake Booster. Normally, there would be a vacuum line to the booster from the intake manifold. Common design calls for a PCV type valve at the entrance to the booster. Pls check this. It also operates on the same principle and therefore checks the same, you can blow one way but not the other; would have a sliding ball inside that acts as the valve. In some instances, it could be the diaphragm inside that might have a tear.

Of course, the Proportioning valve system must likewise be checked. I have heard a lot of brake problems with K2500 especially the rear drum.

Incidentally, there was a recall order of some sort. TSB 99-05-24-001A SEP 99 which addressed brake pull/wear, the recall involved replacing the proportioning valve.

• The Technical Service Bulletin referenced previously discusses the issue surrounding the proportioning valve. Also, there's a corrosion issue which has resulted in the recall of the trucks in certain states.

SOURCE: 97 Blazer brake pedal making hissing sound

Sounds like a vacume leak from power break booster, when you loose vacume it will stall out the engine if enought vacume is lost. chk. power break booster. and hose from engine leading to booster for vacume leak, booster is under hood, break master cyl. bolts to it.

SOURCE: brakes

Flexible brake lines are probably balooning out causing pressure not to build up, replace flexible to the calipers.

SOURCE: need Rear Brake Diagram for 1994 Chevy K2500 4x4

Here is the diagram,It is always a good idea to only disaasemble one side so you can use the other side as a reference,I also reccomend using a set od brake pliers,they will the disassembly and reassembly much easier.

SOURCE: Hard brake pedal while applying brakes

with the sound of air when applying the brakes, sounds like a bad power brake booster, located behind the master cylinder,large round peice