Recently I've noticed that my pedal pretty much goes to the floor. The pedal has always been spongy but its been good enough that I've never taken any action because I rarely drive the truck (98 F150). It feels like there is air in the lines so I flushed all the fluid in the system. I've pretty much eliminated the possibility of air in the lines so I'm thinking it might be a bad brake hose. With the engine off, I can pump up the brakes and they'll be very firm and the pedal will be pretty high up. Once I start the engine, the pedal goes to the floor pretty much.

Any ideas or tips on checking for a bad brake hose? I'd rather ask around before just replacing random things.

 

Has anyone ever used a brake hose clamp for diagnosing braking problems? Just wondering if its an effective method.

 

I'm having the same problem with my 1999. I've tried bleeding the brakes and new fluid, it helped a little bit but not enough. What exactly is the brake hose clamp method?

 

Sounds like the master cylinder is bypassing internally. Pump the brakes up a few times with the engine running, then hold it. Don't try to slam it through the floor, just hold it normally as if you were waiting on a redlight. If it starts falling to the floor, you'll probably need a master cylinder. Depending on how bad it is, you may see fluid trace on the piston at the rear of the master cylinder where the vacuum booster pushrod contacts it. As far as brake hoses go, inspect visually for any cracks or deterioration on the outside of the line. Hoses are cheap enough, I'd replace them just based on age and mileage.

 

They won't pump up with the engine running, they just go to the floor pretty easily. The only time the brakes will pump up and hold a pedal is when the engine is off.

 

http://www.carquest.com/techbulletin...QB%2000-06.pdf

 

If you replace your lines, go with the braided version.
I use them and they feel better.

 

Hmmm...what shape is the fluid in? I hate using process of elimination, but with brakes, barring visable fluid leaks, I still think you have a master cylinder problem.

 

Roughly how much do they run and who makes a good set?

This is only a truck I drive maybe 5-6k miles a year if that so I'm not looking to drop a lot of money into it.

 

Well I just flushed all the fluid so the fluid is new. I'm going to buy some Speed Bleeders this weekend and see if that'll help the bleeding process.

 

Well so far I've replaced the front two brake hoses and my master cylinder. After bleeding the lines my pedal still goes to the floor after the truck is cranked up. The pedal will pump up with the engine off but as soon as I start the engine, it goes to the floor. Does this sound like air trapped in the lines somewhere still? I've bled the lines a couple of times but no luck.

 

Hows the booster? It could have a small leak in the diaphram?,,,,98

 

My 99 f150 5.4 4wd had the same problem. We repalced the master cylinder and it did not help. We found out the problem was the master cylinder and that the replacement was an aluminum master cylinder. We got a direct ford replacement master cylinder and it works great. That was 11,000 miles ago.

 

Where can I get an aluminum master cylinder and for how much? Is it hard to install?

 

You did bench bleed the master cylinder before installing, right?