Re: Changing thermostat 1980 70 HP Evinrude
Are you changing it as routine maintenance or for a specific reason? Either way......
You need to remove the T-stat housing bolts, then remove the housing carefully, there are pressure relief valves which are spring loaded inside the housing. If the housing is stuck, put the bolts back in finger tight and then GENTLY tap on the housing with a rubber mallet, remove the bolts again and remove the housing. Clean off any leftover gasket material from the housing and set it aside.
Remove the pressure relief valves (they look like plastic plugs that will have a spring on the end) and inspect them for any signs of cracking/melting, if they are questionable then replace them.
Remove the old T-stat and clean the seating surface on the head for the T-stat and the housing.
Make sure that you have any new parts already laid out and identified, when installing the pressure relief valves, make sure the tapered side of the sealing surface seats on the head, the springs will then slide over the side that looks like an X.
Use some quality gasket sealer on the gasket and put it in place, insert the valves and T-stat
Put a bit of sealant on the exposed side of the gasket
Carefully place the housing over the springs and have your bolts handy to get them started (a second set of hands is great for this if available but can also be done with one person).
Do not go overboard tightening the bolts, this is an aluminum on aluminum install, a standard 1/4" drive ratchet will suffice if you take it easy, there is no need to break out the 3/8" or 1/2" drive stuff here!!!
