A full flow oil filter has become completely plugged. What is the likely outcome if the engine is running?

When a full flow oil filter becomes completely plugged while the engine is running, the engine’s lubrication system is designed to prevent catastrophic failures through the use of a bypass valve. This valve allows oil to bypass the clogged filter and continue circulating through the engine.

When the filter is blocked, the oil pressure will rise, prompting the bypass valve to open. This ensures that the engine receives essential lubrication, preventing damage that could occur from a lack of oil flow.

The bypass function is crucial in maintaining lubrication, as it allows the engine to continue operating safely even if the filter is not functioning properly. While prolonged operation with a blocked filter is not ideal and can lead to other issues, the immediate effect of the filter plugging is mitigated by the bypass valve's operation.