I have a 98 extended cab. It has always had somewhat of a spongy pedal and I have been told this is a common problem with these years of truck. A new master cylinder and new calipers and bleeding of brakes and ABS some months ago did not help. I got hearing aids last week and am hearing a lot of things I never noticed before. I hear a noise like air exhausting under dash when I apply the brakes. Is this something I should be concerned about or is it a normal noise that I just was unable to hear before?

 

Nonsense! My 1998 K-1500 has SOLID brakes. If yours are spongy, then you still have air in the system. Didyou use gravity or a brake fluid pump?

 

I had the brakes bled by a mechanic after I put on the calipers as 1 was sticking. I don't know how he did it but the pedal was spongy before and after the caliper work.

 

The sound of air rushing is usually a tell-tale of a bad booster. A bad booster will cause soft brakes on the first or second pump of the pedal. If you can pump the pedal and the brakes get harder I'd say the brake booster. If that doesn't happen you probably have an issue with water in the lines or a leak somewhere.