Truck: 1998 F150, 4.6L 4x4.

Problem: Hissing sound near brake pedal, now I have to push down REAL hard to stop. Brake fluid in master cylinder seems full.

Question: Does this mean I need to replace my booster? Is there a way to trouble-shoot it before I buy a $100+ booster? I don't see any hoses broken or anything (though I have a vacuum leak code as I posted on another thread and am trying to find..) If I should replace my booster,which is attached with two bolts to the master cylinder I've read on other posts that there is a F250 one that is better than the F150 and will go right on...is this so? If so, can somebody send me the part code that will match to my truck without any modifications?

THANKS!
Matt

 

I have the same sound on my 1999 f150. I replaced the power brake booster and it still sounds the same. I have a soft pedal and was told this would help but it didn't. I have tried just about everything else even brought to a brake mech. As for using a booster from a F250 I didn't see anything on that subject. What I did see was someone using a master cylinder from a F250 and using in there F150. The bore is bigger and it is supposed to help in stopping. I haven't installed it yet but plan on installing it in the next month or so.

 

Did you check the hose that goes into the booster? I thought that might be my problem, but it looks okay. I just ordered a new booster and will attempt to install it myself... I'm hoping that helps!

Matt

 

It could well solve your vacuum leak too!

 

There is nothing wrong with the hose that attaches to the power brake booster. Good luck and hope it solves your problem. As for me it was a waste of over $100.00.