test pb booster off vehicle?

[redhead69]

How do you test a power brake booster that is off a vehicle? Is it as easy as puting a vac gauge on it and pressing the rod to see if it holds vac? Is there a tolerance for a leakdown.. so forth.

thanks

eric

[wibilly]

hold your thumb over the end of the hose if the rod moves freely and you hear air leaking it's junk if not and you feel resistnace till you remove your thumb your odds are way better but you still have a 40 year old part

[PICKMUP]

A small hand vac pump, like from Harbor Freight, works OK...or a vacuum brake bleeder speeds things up. Just "T" a vac gauge in to take readings.
I like to bring it up to about 20lbs and it should hold the reading if the booster isn't leaking.
You can then just push the brake pedal rod and everything should work easily & smoothly.