Engine Vacuum Readings. Note the vacuum readings, and any fluctuations, at each speed. Web a high, steady vacuum reading is the sign of a healthy engine.
Engine Vacuum Test Diagnosis
Web if the vacuum reading is steady and between 18 and 22 in hg. Web close the throttle and disable the ignition, or use a remote starter so the engine won't start. If you're at altitude, these readings may be lower (supposedly by 1 inch of mercury for each 1000ft above sea. Cobalt327 ( click here to edit this page anonymously, or register. Web a high, steady vacuum reading is the sign of a healthy engine. Web although atmospheric pressure has been established at 14.7 psia (pounds per square inch absolute) at sea level, a common vacuum gauge will use this level as a starting point. Web engine vacuum is a required condition for a gasoline engine to run. Crank the engine for 10 to 15 seconds and observe the vacuum and tach readings. Check the timing belt or chain, depending. Engine vacuum readings will decrease in higher altitudes.
The vacuum test indicates that the vacuum system and the basic engine is in good condition if the vacuum. Web if the vacuum reading is steady and between 18 and 22 in hg. Engine vacuum readings will decrease in higher altitudes. Hg range at idle speed or faster with the engine unloaded. A diesel engine works differently.) it helps control the engine rpm. Web close the throttle and disable the ignition, or use a remote starter so the engine won't start. Web bykenlayne low but steady vacuum reading at idle may be due to retarded ignition orvalve timing, low compression, an intake manifold leak or tight valves. If you're at altitude, these readings may be lower (supposedly by 1 inch of mercury for each 1000ft above sea. There is a good chance the vehicle has jumped timing. Crank the engine for 10 to 15 seconds and observe the vacuum and tach readings. Web a high, steady vacuum reading is the sign of a healthy engine.
