I've noticed in the last few weeks my brake pedal is at times normal firmness and at other times (on the same drive) it will slowly drop almost to the floor. If the truck is just idling in park, I can press the pedal down and it keeps going, then the BRAKE and ABS lights go on, and it keeps going down, until finally the lights go out and it sort of comes to a squishy stop down near my floormat. I still have braking ability, but not near as much, so I don't want to drive it much until I figure this out.<br>The fluid is not low, and I don't have any leaks that I can see from under the truck. The only thing I've noticed is that my right front brake line is slightly worn from the oversized tires rubbing on it. It's not leaking at all, but the rubber cover is rubbed down to the steel braided inner lining. I know this is bad, but I really can't imagine it is ballooning enough to cause this degree of pedal loss. I've ordered a new set of steel braided brake lines from 4 wheel parts, and will put them on next week. Hopefully this and a good bleeding will take care of this.<br><br>I wonder if it's possible my vacuum system has anything to do with this? Could it be low vacuum at idle? But if that was the problem I should have a HARD pedal- right?!?!<br><br>

 

I'm not sure about the vacuum question, but it sounds correct to me. Maybe someone else can shed some light. I would really expect your problem to be the master cylinder. Every one that I have had go bad displayed those problems. Would recommend you have that looked at very soon. Just my opinion, but brakes are not something to guess about.<br>Ed

 

If you do not lose fluid these symptoms point towards the seals of the master cylinder. <br><br>REPAIR IMMEDIATELY! These seals can blow any moment now when you really need to stop and push the pedal with force. The sealing cups of the master cyl. pistons leak through and the piston just travels through the fluid. <br><br>AlpineRAM

 

as alpineram said check the system for leak and if none are found replace/repair a defective master..

 

I third that! The master cylinder is leaking past the seals internally. Replace or rebuild immiediately.<br><br>Chris

 

Thanks, guys. I'll pick up a rebuild kit today.<br>I didn't even think about that.<br>

 

As AlpineRam said. Don't delay on this. Replace your master cylinder IMMEDIATELY if not sooner!!!

 

REPLACE IT NOW!!! The master cylinder is made out of aluminum and the pistons might have scored the sides. The master cylinder is getting ready to take a dump on you. Trust me, you don't want the feeling of the pedal going to the floor and not slowing down. The &quot;pucker factor&quot; goes to extreme. <br>Tom

 

Amen to all that's been said above - plus....<br><br>If it were me I'd get a new or at the least a rebuilt Master Cylinder from Napa or such instead of trying to put a kit in myself. Unless you are very good and have a good hone and micrometer. If it is not done right you'll soon have the same problem or worse, and if it decides to at the wrong time - look out!!!<br><br>Just MHO.<br><br>Stan

 

Check your front wheel bearings. If they are worn, the caliper on that side will extend all the way before it applies pressure on the disc. It just pushes the brake disc away. Cost me bearings, seal, rotor, spindle and backing plate. Maybe this is why the wear on your brake hose. BTW, I returned the master cylinder I had purchased to fix the problem. :P