2H Engine Oil filter

[oldman]

Where the oil filter mounts there is another filter mounted
on top. It seems to be held on by a snap clasp.
Can anyone enlighten me as to what it does and if
possible a link to a replacement. Thanks

 

[AndycruiserguyLomas]

If its a canister above the oil filter then its some kind of centrifugal secondary filter. I've got one off an old engine circa. 1980. Although I dont know categorically its purpose, I would imagine it removes particles from the oil by centrifugal force by the spinning drum inside the canister against the canister body which periodically must be emptied, hence the snap clasp. There is either one or two 'o' rings to seal the canister which go hard over time with contamination from old oil and prove troublesome to seal. I don't know if this secondary filtration system was for certain markets or was tried and dropped or was an optional extra but I have had a few 60's and only seen the one.
Any chance of a photo? I may be rambling on about something different.

Andy