vacuum pump

[Exekiel69]

How many inches (?) of vacuum do we get out of our pumps? btw does it really measure on inches or what?

Thank you.

 

[icanfixall]

Most will pull 27 inches of mercury if thats what your asking.... :Sly

 

[Exekiel69]

Thank you.

 

[Full Monte]

I don't think the inches of mercury number is sufficient by itself to reveal the health of a vacuum pump. A pump has a displacement capacity as well, and it may reach max vacuum eventually (like in a test), but if it takes a lot of strokes to get to that vacuum, it's likely not pumping the vac. reservoir down to max vacuum very fast. My old vac pump tested fine too, but it made a huge difference on the braking when I replaced it with a new one. If you are doing this because of questionable brake performance, also check your vac system for leaks...especially the rubber grommet going into the vac. power assist unit. Hope this helps.

 

[Agnem]

Very true, I would say within 5 seconds of starting the truck, you should see that maximum vacuum. It is usually the volume and not the presure that gives out first.