When I work on my 2009 225 ProXS I use only genuine Mercury parts from Don - ALWAYS... except...
Gaskets. Mercury, as we all know are proud of their products - real proud. So when I can save money without sacrificing reliability I do. Thermostat gaskets are one of the items on that "save money list"(to be sure it's a pretty short list). Sooo... thought I'd share how I make my own gaskets. Thus far it's been thermostat and poppet valve gaskets. Most everything else is 'O' Rings....
To start. I have a brand new factory gasket that I use as a template and I have gasket material that fills the requirements for the applications.
Next I cut a piece of the gasket material stock that is just a bit lager than the gasket to make handling it easier during the process...
Then I carefully trace the outline of the factory gasket onto the gasket material.
The first thing I want to do is punch the holes. I do this while there is excess materials around the hole locations to keep from splitting the gasket in that area. It's critical that this be done first or I'll be starting over. I have a gasket punch set from MAC tools that I've had for years and works well. A leather punch tool will work as well if the tool supports a hole the size required in this application...
Tool...
Holes punched...
Next step is to cut out the center portion of this gasket... I do this by first cutting an 'X' in the center to make it easier to cut around the traced line...
I will say it takes some really good scissors to make these cuts. I use a small pair of scissors used to cut kevlar and carbon fiber cloth that I ended up with after fixing the stringers on the boat... They absolutely do not slip or push back when cutting on the line. And they cut cleanly all the way to the tips of the scissors.
First I trim out a lot of the center to make it easier to follow the trace line...
Then cut following the trace line until the center of the gasket is removed...
Then nothing left to do but cut on the outside trace line to end up with a completed gasket...
Ok... so I ended up with two gaskets...
Last thing to do... check for fit...
Kind of a blurry iPhone picture but it fits well. My gasket ends up just a tad wider at the sealing area than the factory gasket but it causes no problems with fit or function.