Soft brake issue

[dave110]

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I'll try to explain what I got. The first inch or so of my pedal travel is soft after the truck sits. If I pump a few time or put my foot under the pedal and pull it up I have nice firm brakes but after a few minutes it goes soft again. The pedal will return on it's own but slower than in should. I have no leaks or fluid loss although at first I thought a rear line had gone bad. I'm thinking master cylinder but I am fairly new to the hydro boost system and this started around the time I had the PS /vac pump out to rebuild the vac pump. I have not checked my rear adjustment yet but they were good not too long ago. I'd appreciate any advise. I put this on another forum and thought I'd try here also.Thanks __________________

[MarbleCrusher]

Sounds like a master cylinder to me.-Jordan-

[dually]

Are you sure you dont have liquid on any fitting or line. I have a 01 and mine are looking real crusty.I would also look over everything around the vac pump you repaired.

[Mopar1973Man]

What's your brake fluid look like? Brake fluid should be a light honey color when in good condition but as it ages it darkens. Brake fluid needs to be changed every 30K miles. Brake fluid is also hydroscopic in other works absorbs moisture from the air so as brake fliud ages it gains water but this is a problem because now the boiling point of brake fluid falls. What's your power steering fluid look like? Same here the power steering fluid should also be a honey color too but it will darken as it ages too. It needs to be changed at 30K miles.Just a few basics. But it does sound like there is either air or contaminated fluid in the system.

[dave110]

Brake and PS fluid where changed about a year or 7k ago. I keep thinking air too but would't it be spongy all the time then? After a few pumps I get a firm pedal again. In town driving it stays firm but if on the highway after they don't get used for awhile they get soft. Only the first part of pedal travel though.

[IBMobile]

Check the rubber hoses in the system. Have a helper either a stick between the seat and peddle or person push down on the peddle while you inspect the brake hoses. Look for bulging.

[dave110]

Thanks. Good idea. I'll check the hose.