1998 1500 brake system

[kerstingm]

I just got a 1998 1500 4x4 5 2 Ram that has really spongy brakes. Past owner said she just thought it was a Dodge thing, I know it's not, my question is it the power booster or master cylinder? Fluid is full so I know it's not a busted line or bad wheel cylinder. If I pump the peddle it will build some back pressure, but nothing like it should have.
Is there any way I can check one or the other to know what to replace?
Any suggestions would be greatly appreciated

 

[dapepper9]

Easiest thing would be to try and bleed both the front and rear. If that doesn't do it you may need to go through and do a master cylinder

 

[dudeman2009]

You might want to take off the rear drums and just check everything out anyway. It sounds like air in the lines or a bad master cylinder, that's mostly common.

I don't remember how the shoes in these trucks adjust, whether it's the parking brake or backing up and coming to a quick halt and rocking the vehicle. But a lot of tricks with drums that are as old as ours have adjuster problems due to corrosion. Leaving the shoes too far away from the drum, and can make a big difference in how long the pedal feels. If you already have air in the lines or something, that longer pedal feel will make it a lot worse.

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