MY OLD MAN WENT CAMPING YESTERDAY TUGGIN THE 5TH AND THE BRAKES went soft ??? would that be the vaccuum pump. cuz im looking at a 3hr drive w/tools and a new part in hand. and a cold one when im done o yea looks like im going camping to

 

I'm guessing it's a 99-03 PSD since you posted in here. If so, the brakes are hydroboost, and do not use a vacuum pump. Vacuum pump on these trucks is only connected to the HVAC system, and ESOF 4x4 if the truck is equipped with it.

Check for leaks, check for air in the lines, check for wear on the pads and rotors that would increase brake fade.

 

Another potential issue is "blow by", or leaking seals around the Master Cylinder piston. Changing the MC is not too difficult, and is the perfect time for a complete system flush as well.

First, check hydraulic levels in both power steering pump reservoir (source of fluid for hydrobooster) and in the master cylinder reservoir. Top off if necessary.

Check for and fix any leaks found.

Next, bleed the brakes to ensure that no air is in the lines.

If none of the above resolves the problem, you need to find out if it's the master cylinder or excess water buildup in the hydraulic system. [ Water buildup will result in steam in the lines as the entire system gets hot, and since steam is compressible, it can result in sever brake fading while under heavy use. The only way to eliminat ethe water is a complete brake system flush.]

To test "water" versus "leaking MC piston seal", simply stop the truck on level ground and apply as much pressure as possible on the brake pedal... if you feel the pedal continuing to move down to the floorboard, your piston is leaking by and you need to either rebuild the MC or replace it. If the pressure holds and the pedal does NOT ease downward, then simply flush the entire brake system hydraulics.

Hope this helps.

 

well the old man says fell ok now ( rollin back and forthe) butt when turns the truck off the pedle goes to the floor ??? = NEW BOOSTER

 

Check you Power Steering fluild level. May have air in your booster.

 

Do yourself a favor and have him check that both pads are still in place at all 4 wheels. My pedal "went soft" one day... turns out the outer pad on my left-rear wheel got "ejected"... and the piston went to work right on the caliper. Yep, new rotor AND caliper were needed. Luckily I was already doing new pads & rotors, but still... check it.