Hello all...
Just last week my trusty (and certainly rusty!) '84 Sierra w/ 6.2 started playing games with the brake pedal. At all times I have "good" power brakes and I can lock the tires up and slide even when the pedal is misbehaving.
What happens: At times the pedal works properly and is firm. Braking action starts very soon and seems to work fine. Other times the pedal goes waaaay down (but not anywhere near "bottomed out") before braking action takes place. There doesn't seem to be a rhyme or reason to this behavior. I can use the brakes quickly with less than a second's pause and while the first use may have long pedal travel, the second use is fine. It does not matter if the truck has been running at highway speeds or if has been sitting idling for a while.
As best I can tell, all of the front brakes, the fluid and the belt driving the vacuum/PS pump seem to be in fine shape. I have not checked the back brakes due to lack of time.
Can anyone say what might be going on here? I'd really appreciate some assistance or thoughts...
William The Guesser