I have manual brakes now.
 

Hello, I was re roofing a house the other day and upon driving to the job site I heard vacuum hissing/leaking out and my brake pedal no longer had the x10 force to stop the truck as before. My question is are the check valves bad or is it the diaphragm inside the vacuum reservoir? What I believe are my check valves sit below the driver sheet metal floor pan and the plastic housing is cracked; although I don’t hear or feel vacuum hissing/leaking out. The check valves look like they have a perforated end cap of some sort. Today I went to the dump and made it back although I can’t stop on a dime anymore any help would be appreciated.

1974 C60 350 V8

Re: I have manual brakes now.
 

60 series trucks have air brakes, right? You might want to move this question to the "Heavy Haulers" forum section.

Re: I have manual brakes now.
 

Juice brakes may have been an option on 60 series, don't hold me on that though.

If they're juice I bet you just have a simple vac leak at the booster. If air, and you had a leak, wouldn't you actually have trouble disengaging brakes?

Don't air brakes work by applying pressure to let the brakes off? An air leak would make brakes stay on....?