The canister right behind the A/C compressor is your filter housing, and it will contain a replaceable filter element. The two most popular ones were AC and Fram, both available as extra-cost options at the time of the truck's purchase. Yours looks like an AC, as Fram filter housings were normally painted orange. When you remove the lid, be prepared for a little spillage, so have a big wad of rags or a small pan underneath the filter housing. Once the element is removed, there will be a residue of oil in the housing that will need to be removed with a suction gun or soaked up with throwaway rags or paper towels. I don't have filter element part numbers handy, but I'm sure someone will chime in with them soon. The filter element is sandwiched in between a flange on the center tube, and a spring-loaded washer attached to the housing cover, so pressurized oil from the line attached to the side of the filter canister is forced through the element, and drains back into the oil pan through the tube attached to the bottom of the canister. it's called a "bypass" filter because oil does not go from the filter to the engine bearings. A small orfice in the outlet fitting controls the flow, and a slow, steady flow of oil gets filtered and drains back into the oil pan. If you can't find a number on the filter element you remove, take some measurements and check the parts store's stock for one that interchanges. As long as the element seals at the top and bottom, it doesn't necessarily have to completely fill the canister side to side.
Jerry
Edit: Don't forget to change the rubber ring gasket under the cover!
Jerry
Last edited by Hotrod Lincoln; 04/05/2010 8:11 PM.
