Engines run a slight vacuum in the crankcase or they will leak oil from
everywhere. They usually create this vacuum by venting the crankcase to
the intake between the carb and the air filter. I don't know of any
reason or way to measure it. Why do want to do that anyway?
Possibly you are thinking of a leak down tester? to test the rate of
pressure leakage in a cylinder...
HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.