Technician A says that an engine developing 10" of vacuum at idle is a normal condition. Technician B says that engines with clogged exhaust systems will have more than 20" of vacuum when under throttle. Who is correct?

Question

Quizplus · Accepted Answer

An engine developing only 10" of vacuum at idle indicates a problem, as normal vacuum readings at idle are typically around 17-22 inches of mercury (Hg). Engines with clogged exhaust systems will not have more than 20" of vacuum under throttle; instead, they may exhibit decreased vacuum due to the restricted exhaust flow.

Technician a Says That an Engine Developing 10" of Vacuum