PIN 1H5125 - Caterpillar

Truck, Industrial, And Marine Engines Equipped With External (Outside) Oil Filter Hoses SERVICE TIP: Bearing failures can be caused by a reverse connection of the inlet and outlet hoses to the oil filter. If the oil enters (comes in) the filter through the outlet it can damage the filter element. A damaged filter element can cause bearing failures.
If the hoses are removed or disconnected for maintenance work or replacement, be sure they are connected correctly. The inlet hose from the oil cooler must be connected to the "In" or "Unfiltered" port of the filter base, and the outlet hose to the engine must be connected to the "Out" or "Filtered" port on the filter base.