I pulled them and replaced them on the motor that I fully built. And I pull and replace them on blocks that are very old/corroded.
They are very cheap at the parts store. Funny someone said that this isnt an Iron block and things wont rust, but Aluminum does corrode. The plugs the factory uses are steel and cadmium plated, so there alone you have 3 dissimilar metals. The plugs do corrode. Especially on the inside. If you are fully dissasembling the engine and cleaning it, I say you replace them. Theyre kinda tricky to take out, but not anything impossible. Punch them in w/ a socket of equivalent size, spin them 90* and pull on them w/ pliers (not like youll be reusing them). Install is very easy. Put some gasket sealer around the edges and punch in w/ the smae socket until surfaces are flush and youre done. I think the plug size is 13/16" or 7/8" or some ****-don't quote me. I have a box at home...
Same with the oil galley plugs. They normally need to be drilled out cause theyre installed w/ RTV on the threads. I pull those and replace them and flush out the oil galleys, Especially (ITS A MUST) after ANY machine work is done or if its an old engine...think about it- theres years and years of oil sludge in there. Leaving those plugs on during the cleaning process will not give you the best results possible. Theyre cheap as well. Just a PITA but a torch and or a LH drill bit is your friend!
