Fram Oil Filter
Contributed by Dick Bishop
Summary: A description of the Fram oil filter.
With all the discussion of oil filters on the Nauticat Yahoo web site, I decided to open one up and see what was inside. I have been using Fram filters since buying the boat in '96. I will attach a photo of the components so the simple but effective design can be seen.
The oil seems to flow into the filter through the 12 holes arranged in a circle. This forces open a black rubber gasket. This gasket works like a check valve preventing return flow or drainage when the oil pressure drops (engine off).
Oil is forced through the paper element from the outside to the center, returning to the engine through the center screw on threaded hole. At the bottom of the paper filter is the check valve that opens to bypass oil if the paper element becomes plugged or over pressure occurs. Otherwise, the valve remains closed.
I will attempt to measure the pressure required to open the valve. It is quite strong so it is not likely that it bypasses oil unless the filter really becomes plugged.