replacing head gasket

[BigDaddy300]

Was wondering what exactly do I have to do with the head and block surface before putting the new gasket on? Anyone have any advice to offer? It is a 2 stroke 25hp mariner. Anything else I should do while it is opened up? Thanks

 

[Bob_VT]

Re: replacing head gasket

Make sure the mating surface is very clean and you can check the flatness of the head on a sheel of glass. With the exception of making sure its all clean....not too much else except proper installation and torque.

Why is it being changed? Since you are in a "down" status consider your impellar, thermostat, plugs, gear oil, carb kit.....

I like to do it all when the situation comes up.

 

[JimMachinery]

Re: replacing head gasket

When I did the heads on my old Johnson, I used a piece of 1/4" plate glass with 440 grit paper followed by 600 grit spray glued onto the glass to make sure the surface was flat and smooth (I used JB Weld to put a window handle on the other side of the glass). Use "figure 8" pattern and keep pressure even. I shoved clean rags into the cylinders to be sure no fines got into them. If you don't do this, use spray gasket remover and be sure to get all old material off - don't get the remover in the cylinders.

Use the OEM gasket and be sure to follow the torque pattern in the manual when re-installing. Make sure fasteners are clean and lubricated or your torque values will be off. This job can't be done without a torque wrench.

Johnson didn't call for any sealant or adhesive and I followed their advice.

Repair lasted for at least 5 seasons of heavy use - I sold it still running and with excellent compression.

Good Luck!