CYLINDER BLOCK AS 1011171 - Caterpillar

(97Y) 3512 (51Y) 3516 (28Z) Vehicular Engines 3508 (23Z, 1ZF) 3512 (24Z, 3YF) 3516 (25Z, 4XF) Generator Set Engines 3516 (4MJ) Marine EnginesThe mounting flanges on each end of the 8N2001 Oil Filter Base are symmetrical. This allows the oil filter bases to be stacked end to end to provide the correct number of oil filters. Because of the symmetrical mounting flanges, it is possible to install the oil filter base backwards. If the base is installed backwards, oil flows through the filter backwards (from inside to outside), and the oil filter bypass valve will not function. In cold weather, this could result in rupture of the filter element. A ruptured filter element could allow debris into the engine lubrication system.
There have been no known cases of the oil filter bases being install backwards at the factory, but there have been reports involving dealer or customer rebuilds.
In most cases, correctly mounted filter bases will have the 1S7106 Bypass Valve Cover visible (see the illustration). On remote oil filters, the line from the oil cooler goes to the side of the oil filter base marked "unfiltered."
Location of 1S7106 Bypass Valve Cover (1) on 8N2001 Oil Filter Base (2) in typical application. (Not applicable for remote mounted oil filters.)