Help finding a booster

[cbfomoco]

On my 1968 f350 with power disk brakes. I have been having some brakes issues. However today for a moment I had great brakes. It was going down hill foot off the gas so the motor should have been making alot of vacume. After that nothing. Just my reg crappy brakes. So is it the booster that is bad? Or do I need to buy a vac resevor? or is something else the matter? I can hear the booster hiss some inside the cab when the petal is pressed.( however dads does this as well and his brakes are ok) ( it is a 72 with drum brakes though) I have all new vac lines on the motor. A new check valve on the booster. I also took starting fluid today with the motor running and check for a leak by spraying it on the intake, around the carb and booster and nothing. So what do I need? thanks

[fordman]

hissing is the sign of a bad booster.

[BRUTUS_T_HOG]

hissing when pressing the pedal is normal.

run the engine, turn if off, wait about 10 seconds and then push the brake pedal a few times. you should have power brakes and hear hissing for a few pumps.

if you don't then the brake booster is leaking down internally

[70_F100]

When you depress the pedal, you should only hear a quick hiss, then quiet.

If you have a continuous hiss, like Fordman said, bad booster.

[cbfomoco]

Well i borrowed a vac guage and the motor is pulling about 17 in of vac so i have decided that it is the booster. So here is my next question. Does anyone know where I can find a booster for a 1968 f350 with Disk brakes? From everything I have found it is a one year only item. Also if not can any one tell me if a 69 up booster will work as I can find one of those? I know that it looks different and the rod is different but maybe someone can tell me.

[DCrusher]

Here is a easy way to check I thought the samething that my brake booster wasn't working... Kill the engine Now step on the brake pedal Now start the engine you should feel the brake pedal go down a little more the booster is working..

I hope this helps.

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[hazelnut]

If you find that your booster is bad you can go by a big truck repair shop and have a new diaphram installed, had one done about 10 years ago when i couldnt find a booster i needed. not all truck repair shops can do it, ask some truckers if they know a place that dose it in your area.