tarheelracer

On all of the threads about bad brake boosters I searched, they referenced a hissing sound coming from under the dash. Is this sound only when you are pressing the pedal or is it constant. I have a whooshing sound whenever I push the pedal and it seems that I'm not getting much power brake. I can't even get the anti lock to engage when I slam on brakes as hard as I can. Doesn't this seem pretty indicative of a bad booster?

aminnich

Yes, the vac leak only when brakes are applied is typical of a bad booster, as are your other symptoms.

CorvetteMike2024

My experiences with bad boosters. Generally they crack down by the exhaust manifold. I have always changed them out. But recently, some one posted here that they have patched the cracks on them with an epoxy resin. If it works, its going to be my new approach to repairing them first. I have changed a few, and its a challenge.

Corvette Mike

steve40th

I did this little modification to keep boosters from cracking due to header exhaust heat. The #7 tube s very close to the plastic booster. (you can put a ZR-1 as they were metal). Guldstrand did this same modification, using a heat shield, to avoid cracked boosters as they were experiencing this when testing GY 315/35ZR17's for GM, and they had a 383 with headers.
You can see the heat barrier wrapped around my booster. Not the best shot, but it works. It dropped 250 degrees of heat on booster.

And the material used, standard heat barrier for HIGH HEAT steam pipes, for example.

Demonic85

Lately mine has been making the hiss but only during the first few minutes of driving, doesnt want to brake well either. Then sometimes it brakes just power like it has plenty of power, still a bad booster?