oil filter information needed

Hi i have a 25 with an oil filter made into one of the side covers. The problem i have is there is no element inside just a round tube sticking up and a oil drain back into motor. Does anyone might know what they used for the filter? My parts book for my 25 doesnt even show one nore does it show and oil filter assembly as parts. what would be somthing i could make to put inside it to catch dirt? Some of the late 20s also used this style. i put a picture up to show what it looks like i can take one of the inside if needed.

thanks ian

The early diesel engines from the mid 30s only had a series of brass screens that were taken out and washed and reused.Cat had an update filter that used the same paper element as was used in the 311,315,and 318 and others of the late 40s.So it doesn't surprise me that the gas Cats didn't have a filter as we know them today.I have also seen industrial engines from the 40s that looked like the oil filter was an add on or at least an after thought.So I would think Cat had a updated filter that was added to most.My dad used a RD6 into the late 70s and it never had the"real" filter added.But I am sure those that know more will be along soon.Good luck to you on your project.Ray

There was a thread this past spring about that oil filter. It was on a 25 also. I'm pretty sure that if you do a search, you'll find that thread. I remember reading it, but don't remember the details.
Jeff