[garrstim]

I removed the oil filter canister on my 1960 1000 series 305A to find inside a wrong filter and a mystery. At the base of the canister was a lone spring surrounding the threaded bolt that mounts the canister. I purchased a correct WIX 1121 from NAPA. The 1121 filter has cork gaskets on each end and a feature in the bore of the filter that will allow the spring to penetrate the filter a bit but be stopped by the feature and then be compressed when the mounting bolt secures the canister to its adaptor on the block. WHAT DOES THE SPRING DO?? Am I missing some part that would make the spring and the missing part act as a bypass if the filter became clogged? Or perhaps the spring simply pushes the filter up for easy removal when filter is to be changed, which would seem silly?

Also, I think I remember that on this canister type filter the canister should be filled with oil before mounting to engine? Probably would make a mess with leaks around the bolt head at bottom before bolt is torqued, but makes sense.

Help me to understand, please.