I change dmy spark plugs this afternoon and fired itup to make sure everything is okay.She starts to idle rough and there's this hissing sound from the vacuum line to the brake booster.all of a sudden the vacuum line pops off the brake booster and I can't get it hooked back up.Do I need another booster or can this one be fixed?On the end of the vacuum line there is this white plastic peice and it will not hook back up.I did'nt even get close to the booster when changing plugs.I don't know maybe it's time for things to give out?
Can I drive it like this?-Thanks for all the help.-Ken

 

The white piece at the end of the booster is what holds the vacuum in the booster. Driving without that hooked up means you will NOT have any power brakes. You can still stop the truck but it will require considerably more effort.

 

Brake booster vacuum check valve. These used to be available in the "help" section of the auto parts store. I don't know if they still have them.
Napa is a good source for items like this. My local store stocks them.

 

What is the proper way of replacing this check valve?Thanks for the input-Ken

 

The check valve is just stuck in the grommet on the brake booster housing.
Disconect the vacuum line, if the valve came apart take a pair of pliers and just pull out whats left in the booster.
To install, press the new check valve into the grommet on the booster and hook up the vacuum line.
Start the engine and check for leaks.