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Update: Water in Bottom Two--Power Head Off Now - '73 65hp Johson

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  • Update: Water in Bottom Two--Power Head Off Now - '73 65hp Johson

    Thank you all for your help troubleshooting my intermittent WOT issues. The power head is now off. I've posted photos of the exhaust manifold parts and gaskets. Looking for advice on proper way to clean this thing up. I'm thinking solvent and a wire wheel on the castings. I'll need to buy a proper gasket scraper also. Any suggestions on how to clean the carbon gunk build up would be greatly appreciated. Gaskets will be arriving in a couple days. Thanks again!

  • #2
    The covers will be warped !----Use a piece of glass plate and valve grinding compound to lap them flat.

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    • #3
      Good advice, racer. Thanks!

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      • #4
        In case anybody wonders why OMC went bankrupt, there is one example. Building crap like that didn't help. If you examine those parts carefully, you will see that the area around the ports is thin and not supported on the other side. They warp over almost nothing. I could point out several other examples of poor engineering. Add all that to some national problems of the day and you have a recipe for bringing down a giant.

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        • #5
          A far cry from what Ole Evinrude had in mind. I have a '50 Fleetwin in the garage. Better built and still runs. I'm just hoping at this point, the castings are flattenable. Would you have any suggestions on how to clean that mess up? Thanks for your insight, F_R.

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          • #6
            I wouldn't be real concerned about the carbon, just do what you can without heroism. But what cannot be over emphasized is the flatness. Personally, I'd put in a new baffle plate. However, the last time I looked they were NLA. I suppose it could be milled, but that's getting into a specialized project. Besides, you don't want to make it any thinner because it already is a thinness problem. Lapping on glass is a traditional method if you manage to do a good job of it.

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            • #7
              Some Combustion Chamber Cleaner, or CMC Intake Valve Cleaner for DI engines would probably do a fair job of softening that carbon in the exhaust manifold

              F_R... Too bad about the engineering shortcomings, as those little engines were quite popular for many years. and were High Output/cu" engines as far as recreational engines went

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              • #8
                I agree, great engines otherwise. Trouble is we have a special problem here in FL lakes. Water weeds. And that's where the fish hide. Get tangled up in those hayfields and it starts to steam.

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                • #9
                  Nice advice.

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                  • #10
                    Thanks everyone! I'm on it!

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                    • #11
                      Hi everyone. I think for once I got lucky. Only the outer cover plate has a warp, and I'm not convinced that it's legit. When laid flat on the glass w/paint side up, the bottom (fat) end end bows up slightly. Maybe came from the factory that way? It's easy enough to flatten with hand pressure--I think the bolts will do their job and flatten it ok--if it had to have a bow, it went the way I'd want. The other two castings appear perfectly flat (which one is the baffle plate, away? I did run them over valve grinding compound a bit to clean them up and take down whatever hight spots and burrs there might be, mainly the center of the outside cover. Not many weeds around this part of Lake Erie. Maybe previous owner had a bad impeller? I'll have more photos soon.

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                      • #12
                        Indeed you are lucky. But just as a point of information, using your picture, the trouble spots are at the arrowheads, but on the opposite side from the view.

                        Not only is the metal thin but notice there is nothing at the arrowhead areas to keep the plate pressed tightly against the cylinder block.

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                        • #13
                          Another picture of a baffle plate

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                          • #14
                            Point taken, F_R. I'll certainly do a double check on that, maybe from under a piece of glass. Thanks for coming back with that!

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                            • #15
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                              Here are some photos of my baffle plate, along with your diagram for comparison, F_R and anyone else.

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