sealant on gasket

I am going to replace the temp switches on my 86 Evinrude 150.
I need to know do I need to put sealant on the head cover gasket and the thermostat gasket or do I install them with no sealant?

Thanks, Sparky

None just tighten them in a cross style pattern.

BRP sells a product called Gasket sealing compound that's made for the job. Comes in a can with a brush built-in to the lid. I'd use it on the gasket and goop it on all the bolts too. It also works well on gearcase and water pump bolts to keep corrosion out of the threads. You can probably get by without it in fresh water but I wouldn't dream of putting it together around brackish or salt water without the sealer.