[Farside]

About a week ago I noticed that I've lost my power brakes on the 70 XR7. I have to really put pressure on the pedal to get a solid stop. I asked a guy at the parts store what he thought it was (he knows older cars) and he said that it was probably the brake booster. I checked MustangsUnlimited and the price tag was $250 smack across the face! Oddly the parts store said they had it for only $115, I assume the parts store will have inferior parts and fit??? Anyway, can anyone weigh in with their opinion that the brake booster is probably at fault here, and if so how big of a project am I looking at in fixing it. A side note I've also noticed that when I start my car up after it has been running for a while and sat briefly - that I'm getting sound coming from the back of the engine compartment near the firewall - it almost sounds like a steady electronic alarm humming sound. (like early 80's cars when you leave the lights on or keys in the ignition when getting out) It's not screaming loud but it can be heard inside of the car with the engine going. Could this be related to the brake situation?? Any help with what's going on\buying MustangUnlimited Vs. Parts Store parts\how to fix this problem would be greatly appreciated.
eric

 

[James]

Brakes

Before you spend the $$$ for a master cylinder, first check the brake fluid. If one of the sides is down, you may have a leak in the line or more likely - a wheel cylinder. I experienced this same thing this last week and discovered a leaking rear wheel cylinder. Don't forget to bleed the system if you change anything. Good Luck!

 

[Cougrrcj]

Brakes

That noise you hear at the rear of the engine bay could be a vacuum leak, either from a hose, the plastic tee on the firewall (if you have one), or even a bad checkvalve on the brake booster, booster-checkvalve grommet, or possibly a leak in the booster itself.

Sorry. You're gonna have to find the location of that noise to be sure. No matter what it is, it shouldn't be there!

 

[badcat427]

A hard pedal means your power assist is not working.
Either no vacuum to the booster or the booster is bad.
One from the parts store would be fine,and easier to have replaced under waranty.

 

[modifiedmark]

The way I always was told to check the booster is to step on the brake pedal and start the car. When the engine starts the pedal should move down about an inch and hold solid. If it dosnt go down that means a problem with the vacuum supply or a bad booster. Also like badcat says a hard pedal is also a sign of a bad booster.mm