Engine Vacuum help

[scarney1988]

When I attach a vacuum gauge to my PCV breather hose (while it is still connected to throttle body) I get little to no measurable engine vacuum.

My brake booster line pulls about 22psi steady (if I remember correctly).

Any thoughts? Anything I'm missing? Can anyone else check their engine vacuum with a known good gauge?

Details:


1990
3sfe
automatic
2wd

[white90dx]

All is well then.

There is a one-way valve at the brake booster (metal fitting-like thing at the end of the hard line near the brake booster). It keeps vacuum in the booster so you can have boosted brakes if the engine is off, etc.

Air from blow-by is always flowing from the engine case to the throttle body through the crankcase breather, and will generally have little to no vacuum on that line (and possibly even slight positive pressure near the head side of the hose).

If you want to check engine vacuum, you want to use a vacuum line that is elsewhere on the manifold without air flowing through it. There should be one or two extra ports on the back you can use any time.

-Charlie