Crankcase pressure testing is performed with the engine at ____________.

Crankcase pressure testing is performed with the engine at high idle, no load to accurately assess the internal conditions of the engine. At high idle, the engine is running at a speed that allows the oil pump to circulate oil effectively, optimizing the engine's lubrication and cooling systems. This condition helps to simulate the engine's normal operational environment without the added variables that can be introduced by applying a full load.

When the engine is at high idle, no additional mechanical resistance from a load allows for a more controlled measurement of crankcase pressure. This is essential for detecting issues related to the engine's sealing, such as worn piston rings or damaged gaskets, as any air leakage under load conditions could mask or influence the pressure readings.