Hi all, new to the forum. I'm having a weird braking issue on my 'new' 2001 f250 diesel, AT, 112k miles, 2wd.

If I brake normally, the pedal will depress pretty far with minimal resistance. Once it's pretty low it will firm up and then slow the truck as normal. Sometimes the ABS light is on.

I had it at a shop and and they found a leak in rear-left brake line and fluid was low. Once that section of line was replaced it actually seemed to fix the problem- but the same issue came back just 2 days later. I took it back to them and they said it wasn't leaking. I bled both rear lines when I got home to be sure and didn't find any air.

I've found that if I quickly apply brake that the pedal will be firm immediately and will stay firm so long as I keep constant pressure on it- but as soon as I let off a bit then the pedal will lower under the weight of my foot and then firm up again when near the floor.

I've read that if the system runs low then air can get in ABS unit and needs to be bled w/ special tool or by engaging ABS and re-bleeding. So I did some hard stops on wet pavement and the ABS didn't seem to be cycling. Further confusing me, I found that after especially aggressive full stops that the truck would not accelerate afterwards- I'd then shift thru gears and push on brake pedal a few times then it would accelerate and drive as normal... this was not a one-off thing, it did it after 3 or so different hard stops.

Thanks in advance!

 

I had it back at Firestone today- they said the issue is the hydroboost, but sited no other reason than the feel of the pedal... Seeing as they originally said the issue was the leaking brake line I'm not inclined to trust them. And regardless they don't change hydroboost units as they've had "bad luck" with them- they told me to go to the dealer.

There is a small power steering fluid leak (not sure if from the pump or a fitting). Prior to the brake issue the steering was getting hard so I flushed the power steering and that immediately fixed the steering issue- though afterwards the brakes were no better- maybe even a little worse.

 

Issue was just master cylinder after-all...

Bizzare Brake Issue - '01 F250 PSD - Diesel Forum - TheDieselStop.com