OIL SYSTEM D/O (3)DESCRIPTION (continued)COLD START PRESSURE RELIEF VALVEThe cold start pressure relief valve is installed downstream of thepressure pump mechanism side. It protects the oil system by relievingthe pressure back to the pump inlet, when exceeding 580 PSID. Thevalve is normally closed during engine operation, and will only openwith a cold oil condition or blockage of the system.PRESSURE FILTER AND PRESSURE FILTERDIFFERENTIAL PRESSURE SWITCHThe pressure oil filter is installed at the bottom of the oil pumpassembly in filter housing and contains a 145-micron filter element.The element is of metal type and can be removed and examined. Afterinspection it can be cleaned and used again providing it is notdamaged. A pressure filter differential pressure switch, installed onthe filter housing, contains a differential pressure sensitive mechanism,which monitors the filter condition.