The brake peddle seemed to be getting spongy on my truck over the past couple weeks. It probally changed slowly enough where I didn't get alarmed by an imediate change. Anyhow right before I left on my trip I got a brake and antilock light. The master was low so I topped it off. The brake light and anti lock light will come on and then go off when I press the pedal and I hear a click when the lights go out. I suspect the matser clyinder is going out. The truck still stops but once and a while it will give squirelly on stops and has a higher pedal it I let off and apply the brakes a second time. Where is a good place to get a Master cyl at? Or who has a good reman? I really don't want to be stuck with one that I change every 3months. Or is this something else other than the master. There are no leaks noted elsewhere so my guess is the rear of the master is leaking.

 

I just went through a similar problem. The anti lock and brake lights were on since I bought the truck, so I replaced the rear shoes since they were getting close to the rivets. When I got it back together it had almost no pedal and felt very spongy. Did a search here on RWAL and took most everyone's advice which was to clean the sensor on top of the differential and bleed the rears thoroughly and reset the system by taking the battery lose for a few minutes and make sure the shoes are adjusted right. It worked very well, got better brakes than I ever had on most trucks and the lights went out .Worked for me and it didn't cost anything..wv smoker.......

 

Definately start by checking/adjusting the rear brakes, then THOROUGHLY bleed the whole system. If the pedal still feels iffy then consider a master cylinder change.

On mine the rear adjusters didn't, and witht he extra slack it became a 2 pump wonder. Your's may have just gotten low enought to suck some air in also...

 

Sounds like the rear seal on the master has failed and taken the booster with it.

 

Sounds like the rear seal on the master has failed

My sentiments. Try MC after inspecting and adjusting rear brakes properly.