AC PM-9T Filter canister
 

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.

Re: AC PM-9T Filter canister
 

The canister filter on my 305E never came with the spring. The filter centers on the center bolt and seals using the cork gaskets. Torquing down the bolt should compress the filter somewhat.

The bolt is sealed by a o-ring on the bottom, it should not leak when the bolt is loose and this way the filter can be filled with oil to prime the filter.

You could start without priming but I would recommend disconnecting the coil wire to the distributor to prevent start-up until you get oil pressure.

Don't forget to fish out the old gasket out of the oil filter adapter on the block.

Good luck!

Re: AC PM-9T Filter canister
 

The bolt has a copper gasket under its head. How thick is the O-ring that would go on the bolt inside the canister...like perhaps 1/8" 0r 3/16? Probably not critical but heavy enough to keep the bolt in place while plugging the bolt hole using the weight of the bolt against the o-ring until things are torqued.

Do you imagine that the spring has a pressure bypass function in a some particular run of the canister design? Wish I could find an engineering drawing of the PM-9T canister.
Thanks for your quick reply.

Re: AC PM-9T Filter canister
 

Here is the inside of a canister. Spring underneath as bolt goggles from side to side.


Here is a description posted from the Archives aka Previous Forum Posts section, by Rod Issaquah, on how the oil canister bolt goes together.

Re: AC PM-9T Filter canister
 

The spring provide a preload on the filter to keep it seal, due to manufacturing tolerance/and different manufacture.

The oil filter by-pass is made inside the filter base. It is made of phenolic with a spring holding it in place. On top of the base is a large plug where the by-pass get installed, see attached pictures.

Re: AC PM-9T Filter canister
 

Does the spring go on top of the filter between base and filter or under the filter in bottom of canister?

Re: AC PM-9T Filter canister
 

Cut away photo shows it under the metal disc at bottom of canister

Re: AC PM-9T Filter canister
 

Shiny tape aluma-view