I decided to cut open a popular water-separating fuel filter used on my boat, mostly out of curiosity and to see how they work, and to compare with typical oil filters. This model - Mercruiser / Quicksilver 35-802893Q01 is very common on Mercruiser engines.
The media is supposed to be different from typical oil filter media, and has the reported capability to block out water, but many owners debate how well this works. The primary method to separate out water is by gravity: there is plenty of space below the filter media so that the heavier water sinks and does not reach the filter media.
The filter is constructed almost identical to an oil filter, as you can see by the pics. The major differences you can see are: inside of the can is painted to combat rust, but not the end plate; extra space below the media; the spring is held in place with some sticky asphalt-like adhesive; the spring is very thick; the can is fairly thick- much like a good oil filter.
The media is supposed to be different from typical oil filter media, and has the reported capability to block out water, but many owners debate how well this works. The primary method to separate out water is by gravity: there is plenty of space below the filter media so that the heavier water sinks and does not reach the filter media.
The filter is constructed almost identical to an oil filter, as you can see by the pics. The major differences you can see are: inside of the can is painted to combat rust, but not the end plate; extra space below the media; the spring is held in place with some sticky asphalt-like adhesive; the spring is very thick; the can is fairly thick- much like a good oil filter.