What causes high engine vacuum?
What causes high engine vacuum? Low vacuum can be caused by leaking or disconnected vacuum lines, leaks in vacuum operated devices or intake manifolds. The highest vacuum will be on the slow side. An open throttle creates less vacuum than a closed one. What does a fluctuating vacuum gauge mean? If the vacuum reading fluctuates within the normal range-the gauge needle bounces around a lot-uneven compression (broken rings or leaking valves or head gasket in one or two cylinders) is a likely culprit. If vacuum drops intermittently at idle, one or more valves may be sticking open or dragging. How...