Type something to search...
to navigateto selectESC to close

Engine Vacuum Gauge Interpreter

Interpret Your Vacuum Test

Run this test on a fully warm engine, parked safely, with vacuum source connected to intake manifold vacuum.

Typical Vacuum Baseline

  • Sea level warm idle: roughly 17 to 22 inHg.
  • Altitude adjustment: expected vacuum drops about 1 inHg per 1,000 feet.
  • Healthy snap test: quick drop, then rebound above idle before settling.