After driving 20 miles on the NYS Thruway, I was braking for a toll booth. The best way to describe it was that the brake pedal felt very high and hard, and it wasn't stopping well. I pumped it once and the pedal softened out and the truck stopped fine as always. Thirty miles later at the exit ramp the same thing happened. This time I applied a little extra pressure and the pedal went through the hard stage and into the lower, softer, normal operation. Three miles at low speed to the house and the brakes worked normally. The fluid level hasn't moved, and I don't see any signs of leakage.

Does any one know what this problem might be? Thanks, I've gotten nothing but great advice on this forum, and I appreciate it, John

 

you may have a sticking brake caliper.are any of the rotors warped?.you can take the calipers off and grease just the slides and see if it cures your problem.also check for pads that are wore more than others. keep in mind that the fronts always wear faster than the rears but if one corner's at 30% and another is at 60% you can be relatively sure that's the one sticking on you.if they all look good look to your master cylinder next.

 

When is the last time you flushed your fluid. Sounds like air or water pocket....they like to hang around in the brake caliper piston reservoir where rust is formed causing sticking caliper pistons....I would flush the brakes and go from there.

 

I have never flushed the brake fluid. Do you know where I can find the correct prcedure to do this?

 

There arte several topics with this and the Super Duty forums...just use the Serach feature key in Brake flush...you will have some great info. Personally I picked up (2) packages of brake speed bleeders Item 12701 from Advance Auto...they're everywhre (Advance, Autozone, Pepboys, Carquest, etc...) replace all your current bleeder valves with these. They have a small built in check-ball....which allows you to do the job yourself, or with a helper at least do it easier. Get some 1/4" ID clear tubing (approx 4-5 ft) and a clear recepticle to collect the old fluid and junk. I used a couple of old juice jugs. Pick up 3-4 qts of DOT3/4 Synthetic brake fluid...get something nice...Valvoline, etc...Have your helper pump the brake pedel while you control the bleeder valve...just crack the bleeder valve open enough so that fluid is coming out and wait for it to be clear...no worries about air being sucked back in while your helper is pumping the brake pedel due to the ball valve. Keep in mind.. you will want to start with the right rear, then left rear, then right front, then finish with the left front. Before you go to the caliper bleeder valves, suck as much as you can from the brake fluid reservoir (make sure you don't get any brake fluid on your paint...it will eat it...if so, wipe up quickly)...also as soon as you suck the old stuff out, quickly replace with the new...IMPORTANT, don't ever let the fluid level of the reservior get below the plastic molding line the reservoir....otherwise you run the risk of exposing your abs sensor to air...not good. Good luck.

 

Thanks for the help, gonna flush it tomorrow. John

 

While doing the brake flush today, I noticed a screen at the top of the brake fluid reservoir. I wanted to siphon most of the old fluid out of it rather than pumping it all through the right rear line as I bled it, but couldn't figure out how to remove this screen to get my turkey baster in. Is there a trick to remove this screen? It would be nice to know for the next flush. Thanks, John

 

With your description in your original post. I would question the vacuum pressure or brake booster.

 

i wouldnt think it would be a fluid problem but?.

 

Yeah...it can be a PITA to remove...I just used needlenosed pliers and yanked it out....sucked all the old out, quickly filled her back up, then put the screen back for the tope offs.