Vacuum pressure for a diff lock.

[mark23]

Just installed a front locker and ran vacuum lines. Ran a line to the vac. res. from the pump on my 1.9 tdi. Pressure seems very low. how much pressure should there be/take to engage ?

[Wildthings]

Pressure and vacuum are pretty much to opposite of one another. Can't say what you actually need, possibly 6-10 inches of mercury, maybe more.

[Californio]

I have the same question: what vacuum does it take to operate a decoupler or diff lock?

Mine are wonky (take forever to disengage). I rigged up a vacuum
gauge to the front Y fitting and am getting 24-26 at idle, 19-20 on hard acceleration, 28-29 on decelerating downhill.

Am I right in thinking that's enough to operate the decouplers and start looking elsewhere?

[jberger]

Depending on the condition of your shafts\actuators... Usually by 10 inches it is operating. Sometimes less. Your reservoir should hold max manifold vacuum or max pump vacuum until it is being consumed as there should be a one way valve in place.