COMPRESSOR GP-REFRIGERANT 2P8233 - Caterpillar

All 3500 Series EnginesAll 3500 Series Engines use an 8N386 Flange and a 1W7278 Connector between the oil pump inlet and the oil pan group. The serviceman must work carefully during removal and installation of these components to make sure bolts and washers do not fall into the 1N3150 Oil Screen Housing. A bolt and washer left in the housing will be pulled into the pump when the engine is started and will damage the oil pump.
Four 2A4639 Bolts and four 5M2894 Washers are used to fasten the flange to the oil pump. See the illustration. The two inner bolts and washers are captive; that is, they can not fall out of the flange unless the flange is turned during removal of the connector. But, if the flange is turned, it is possible for the bolts and washers to fall from the flange into the 1N3150 Oil Screen Housing. See the illustration.
It is Caterpillar's recommendation that the four 2A4639 Bolts and 5M2894 Washers be removed and kept together until assembly.
During major repairs when the oil pump is removed, the recommendation is to remove the 1W1564 Screen Assembly from the 1N3150 Oil Screen Housing if the oil is drained from the pan. Then, inspect the housing for parts before assembly of the components.
If the oil is not drained, the recommendation is to put a clean shop cloth in the housing above the screen to keep parts out of the housing. If part of the cloth is left out of the housing, it will help the serviceman remember to remove the cloth during assembly of the components.
Make a reference to this article in the Disassembly and Assembly sections of the Service Manuals for all 3500 Series Engines.
Typical locations of the parts. Group shown is for a 3512 Marine Engine.