Never had this happen before...

[4Speed]

With less than 10 hours I went to remove the fuel filter and it separated. Looks like some pretty cheap/ thin plastic...
Yes, its a OEM Mercury part as I never install aftermarket.
Yes, I backed off the set screw prior to removal
Yes, I lubricated the O-rings when installed.

Never seen this in 16 years of winterization.

[4Speed]

I found one of my old filter boxes and according to the picture it looks like there are 6-8 webs connecting the threaded top of the filter to the main body. The Mercury/ broken one I installed only has 4. It will be interesting to see what the new one has.

[25two.stroke]

All 7 I have on the shelf (OEM) have 4 webs. Never seen one break like that and I have used both aftermarket and OEM

[4Speed]

The more I look at the Quicksilver box, it probably only does only have 4. Couldn't believe what a new Mercury one cost... just over $70.
I wonder if the filter had swollen as once I unscrewed the top, I had to pry a little around the sides/ edges of the filter and place a pair of needle nose pliers in the center hole and pull them apart so as to "break" it free.

[skialot2]

Any chance you got a NOS that has been sitting on someones shelf for 30+ years? Plastic gets brittle over time and not made for ethanol way back then.

[FUJIMO]

...they're giv'n em away on e-bay...

[4Speed]

I saw them on eBay but figured I would support the local Mercury dealer and I was in the middle of the winterization process and didn't want to wait, but will plan better next year as $70 vs. $10-$15 is a tuff pill to swallow. Where it was difficult getting the filter body out out after the top separated, I am thinking it probably broke when I was removing it... I was thinking a possible ethanol issue also. I don't think it was a self life issue as the dealer moves a lot of inventory as they sell several boating manufactures.
I will say as a test that the new one went in much easier than the broken one did when I screwed the top back in. Installing the new one I only needed to use the special wrench for the last 1/2 to 1 turn, when screwing the old top back in I had to use the wrench for the last couple of revolutions.

[25two.stroke]

Yeah and don't put them that tight. Once the oring goes down in the bore it is sealed...it doesn't need to seat against anything real hard. I just put them in till the top seats and looks like its all the way down. I don't put them in like a fastener or a pipe fitting.

[David - WI]

Being a "water seperating" filter... I wonder if long term exposure to water in the filter causes the plastic to swell a bit? Some plastics do.

[4Speed]

Good point. I drain both sides of the filter housing (Optimax) into a clear plastic bottle and let it sit for a day or too and haven't seen any water. I wonder if Mercury Stabilizer or QuickClean could have weakened the plastic as the manual calls for 2 teaspoons of each in the housing then run at idle for 5 minutes... Anyway, its been issue free for 16 years - probably operator error on tightening like 25 mentioned.