1958 Mercury mark 10

Home › Forum › Ask A Member › 1958 Mercury mark 10

Viewing 10 posts - 1 through 10 (of 37 total)
1 2 3 4
  • Author
    Posts
  • March 19, 2023 at 6:05 pm #274146
    mark weaver
    Participant

      I am working on my 1958 Merc mark 10 I picked up a few years ago. It has 115 and 115 compression, new Sierra condensers, have changed the coils for the THIRD time, they read 7.3 ohms…both of them and tested for continuity wire to wire, there not new but no change with these ones…. from a running engine. I have cleaned the original carb TWICE. I tried two other carbs as well and set them over and over…one turn out, one and a half….two…no difference. If you spin it with the plugs out and grounded on the engine there is excellent spark. I just finished putting a water pump impeller in it and it is pumping great water now…not the easiest impeller I have ever changed but its in and working great….and it will hardly run….spits and sputters and quits over and over again. It will rev up a little and sputter and die. I tried another flywheel, cleaned and set the points OVER AND OVER, took them OUT and cleaned with 600 grit…plain paper drawn through them to clean….Changed the fuel pump, I knew that was not it, it should run until the carb is empty. I have worked on a lot of old motors but never seen anything like this. Anyone got any ideas?? Got good gas, good spark and great compression for one of these and can’t even get it to idle. ANY idea’s would be welcome!

      March 19, 2023 at 6:29 pm #274147
      dave-bernard
      Participant

        US Member

        crank seals crankcase leaks intake port cover leaks ????????

        March 19, 2023 at 7:04 pm #274158
        mark weaver
        Participant

          I checked for leaks, I can’t see anything. I had a 9.8 with a crankcase leak so I looked for any sign….nothing. It acts like fire but it has GREAT spark with a drill. I have had the flywheel off a half dozen times and checked and cleaned and checked again. This old motor has what I thought great compression, is in great condition….VERY clean. I am at my wits end. GOOD fire GOOD compression…getting its gas….can’t see any air leaks or anything like that. They don’t have a head gasket….even if it did it should show on the compression test. I don’t know if the fire is breaking down when running?? I thought for sure it was a condenser….acted like it but nope.

          March 19, 2023 at 9:30 pm #274167
          dave-bernard
          Participant

            US Member

            call me 1 914 310 7086

            March 19, 2023 at 9:55 pm #274168
            mark weaver
            Participant

              Sorry, I don’t have international calling….unfortunately.

              March 19, 2023 at 10:03 pm #274169
              labrador-guy
              Participant

                US Member

                Mark I can only tell you what happened to me.  I was working on a 25hp Evinrude.  I rebuilt everything same as you.  Had spark, when I got it to start it backfired through the exhaust, spit and popped through the carburetor  and just ran terrible.  Eventually I found out I had a junk new condenser!  Guess what?  It was a Sierra condenser!

                dale

                March 19, 2023 at 10:23 pm #274170
                Doug Wilson
                Participant

                  US Member

                  might try another set of condensers have had good and bad ones from Sierra kits

                  Doug

                  how is it motors multiply when the garage lights get
                  turned off?

                  March 19, 2023 at 10:26 pm #274171
                  mark weaver
                  Participant

                    I don’t doubt that Dale….a lot of their stuff…POINTS for example are NOT good. I have a parts 1960 10 hp so I tried the condensers out of it, the original ones that were in it AND the new condensers are doing the EXACT same thing. I kind of ruled the condensers out….I have such GREAT spark when using a drill to spin the motor with the plugs out and grounded. Dave suggested an air leak…it would have to be a BAD one….it barely starts and spits and sputters and quits. This is not my first outboard repair or rebuild and when you get GOOD fire with GREAT compression and the points set to EXACTLY 20 thousands…it should at least run until you fine tune the carb.

                    March 19, 2023 at 10:33 pm #274172
                    mark weaver
                    Participant

                      I may need to but I have tried SEVERAL from parts motors before the sierra’s….NOTHING changes in the slightest. The points time it so that is right…and fire and gas is there so…. I will try new gas in the morning but the gas is not old and used it on another motor a couple of weeks ago but am OUT of ideas.

                      March 20, 2023 at 5:47 am #274177
                      billw
                      Participant

                        US Member

                        Will it STAY running, at higher idle or say, at 2000?

                        I’m wondering about the reeds. I know they are buried but if you take the carb off and look carefully with a flashlight, you can see some of the area. You can also feel around in there with a 90 degree pick, to see if they are closing all the way or if there is a chip off of one. The good news is that with a Mark 10, there are only two reeds per cylinder and they are towards the front of the crank case.

                        What’s the AJ number on the carb? Could somebody have put on a different one, trying to “improve” it? I might have another one kicking around someplace.

                        Long live American manufacturing!

                      • Author
                        Posts
                      Viewing 10 posts - 1 through 10 (of 37 total)
                      1 2 3 4
                      • You must be logged in to reply to this topic.