Home › Forum › Ask A Member › Johnson Md-39 Cooling System › Re: Johnson Md-39 Cooling System
MarvK I pulled my carb off for a cleaning and the water jacket is right behind the choke side of the carb. They used some type of thick brown paint to coat the inside of the water jacket surrounding the cylinder.On a good note I happened to be in advance auto parts last nite and found a roll of felpro #3157 rubber-fiber sheet 1/32" that matched pretty close to the type of gasket behind the carb covering the water passages. When I had the lower end apart I took the entire piston pump apart and degreased and cleaned each piece and then put back together with some lubriplate 105. When I shook the assembly before I put it together I could hear both brass check balls rattling-one was stuck in the cup before I cleaned it and I had to knock it loose and then polished it with some #0000 steel wool. I also ran a piece of 1/16" tig wire up the water tube to see if anything was clogged.Also something I noticed was the faceplate on the end of the copper ram that rides on the lobe of the propshaft had a wear groove in it from use,i changed it out for the one Doug sent me along with the rest of the parts-it had a much better surface to contact the propshaft lobe.