this is the differences, for those who haven’t seen, in the water jackets between pre 78 and post 78 motors. Pretty big difference in rerouting the water. Note the ’78 is my motor, very good compression (135+), runner, trying to solve cooling system issues. You can see the broken off screw in the middle cover orifice, I couldn’t salvage this (tap broke off inside…damn it!), so I ran crankcase sealant/gasket seal/fuel and oil tolerant sealant along this middle ‘wall,’ and then used plenty of OMC gasket sealant everywhere else. Hope this does the trick tomorrow morning when I fire the motor off.
The pic following is off a seized 1979 35hp (typo – should say 79-thru, not 80-thru), although I have a ’85 20hp dead block as well that was seized and the cooling jacket is the same in appearance.
