2nd Gen Non-Engine/Transmission Why Spongy Brakes?

[JoelMartin]

On a 1993 the rear brakes are adjusted but they still are quite spongy. It takes pushing the pedal pretty hard to get stopped. Any ideas why? Thanks

 

[fest3er]

(1) You've got air in the lines. If you bled them, do it again. If the fluid isn't clear, keep bleeding each corner until it is; this is a good time to change the brake fluid. If the pedal is still spongy then, drive it a while and bleed again; there may be air lodged in a corner somewhere.
(2) You mis-installed the rear brakes.
(3) You've lost vacuum boost; but this should result in a very hard pedal, so is not likely to be the problem.

 

[SFPADGETT]

If the above post doesnt cure your problems, then maybe the rubber parts of the brake line could be flexing "expanding" under pressure, which will cause the brakes to feel like you described. We have had trouble on some of our trucks with a similar feeling--but it was actually the front lines causing the problems

 

[TboneMan]

Brake fluid is hygroscopic, i. e. , it likes to absorb water. Try a complete flush. That worked on mine several years ago.

 

[JoelMartin]

Thank you for the help. I'll let you know the results.

 

[MStearns]

Check the steel brake lines running to the rear as well. I just replaced mine. they were so corroded that they just "sweat" brake fluid as my wife pumped the brakes. Of course the worst of it was behind the fuel tank.

 

[JoelMartin]

By the way this question was for a friend. He ended up replacing the hydro-booster and this fixed the problem.