hard brake pedal
 

I'm having an issue with my brakes. Most of the time when I hit my brakes its like trying to mash a concrete block and has very little stopping ability. When the pedal actually feels normal, it stops better but not great by any means. I thought maybe it was my vacuum pump but I pulled the main vacuum line and it seems to have good suction. I have new calipers and pads on the front and I bled the lines until there were no bubbles. I have no idea about the rear drum brakes as to how old they are. I'm thinking a master cylinder or booster problem or maybe both? Any other suggestions?

When it's hard most/all of the time like that, it's generally either vacuum or booster. I've also learned that anytime I replace a booster now, I replace the master cylinder at the same time, as often there are issues there as well. (Often a seal in the master is starting to leak, the fluid kills the booster diaphragm.)

Same thing with me, it was my vacuum pump. The pump should be pulling at least 19 on the gauge.

Sounds like lack of vacuum from dead/dying vacuum pump.

I was thinking vacuum pump but someone suggested pulling the main vacuum line to see if it sucked to my finger pretty good and it did so then I began to have doubts. What kind of gauge can I test it with?

Any vacuum gauge will do.

cool, thanks

Brake Light possibly caused by dieing vacumm pump - Oilburners.net
Read my thread ^^^^^

My vac pump would easily pull 25 inhg at idle even right before it died.

While we are on the subject, my brakes are stiff if I hit the pedal fast but if I slowly depress it, the brakes are soft and the pedal travels further. Is this vacuum related?

Someone cut me off the other day and I was surprised when I stomped the brakes and nothing really happened. They didn't seem to move from the hard position, ie: they didn't suck down or at least not quickly.

Time for a hydroboost! :-drink

I would love to but the wallet won't agree with me on it. I think I need new brakes anyway, I get a squeak/squeal every time I apply the brakes.

F250 hydroboosted his brakes and he seems to like it.

He also says that they feel like manual brakes, I like my vacuum brakes sorry.

there's no comparison in the braking power.
if you want to stop without the mushy brakes,that's the cure all.
iv got a hard pedal cus i haven't swapped to the f-super duty pedal yet.i dunno where to buy one.:(

LSO,if you find out you need a vacuum booster send me a pm if you don't mind a used one (under 80k miles.)

Well I checked the vacuum pump with a vacuum tester and its only drawing around 10 lbs. Sometimes it'll jump up to 15 but never any more. Guess its time for a new vacuum pump? Thanks 250, I'll send u a pm when I get back to a computer, can't figure out how to do it on my phone.

I swapped in a junkyard Hydroboost setup, using all my original brake parts, and the pedal isn't hard at all. Feels much better than the stock setup (before it went out). Best upgrade I've done so far.