1958 Lark 35

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  • July 14, 2015 at 2:40 am #20111
    flathead
    Participant

      I dropped the lower unit, the impeller is still in good shape. I have to assume the rubber was in there before I got it. I tried running it w/o thermostat the other day. It started pumping water right away which you’d expect since you don’t wait for it to heat up. Then slowed, then stopped pumping all together. Same exact issue. I bet if I timed it, it would take exactly the same amount of time to stop pumping every time. I will pull the frost plug and see if I can tell anything. If I can get away from it, I would like to not pull the head. So that sleeve is meant to be in the head? I’d have sworn by looking at it, it was meant to be on the plug. Looks like it’s loctited on the plug. The plug goes in and tightens up good, like it was supposed to. You think I should leave it like it is, or try and put one in the head? This motor is giving me quite an education. I’ll try and check the frost plug out tomorrow night after work.

      July 14, 2015 at 3:30 am #20113
      flathead
      Participant

        Frank, would you know the part number of that core plug? In my manual, it looks like 7X142. I can’t find that number online. I imagine I’m going to have to punch a hole in it to get it out, figured I should try and order it ahead of time.

        July 14, 2015 at 12:57 pm #20123
        chris-p
        Participant

          307541 is the new part number.

          July 15, 2015 at 5:21 am #20181
          flathead
          Participant

            Thanks for the part number, got it ordered. Pulled the plug found a piece of rubber in the lowest hole. I would never have looked there. I won’t know if that fixed it until I get it back together and run it. Hopefully that will be the answer.

            July 15, 2015 at 5:26 am #20182
            flathead
            Participant

              I flushed everything out. Went up the water tubes, down T stat housing, and in the core plug hole with a garden hose. Didn’t see anymore pieces anwhere.

              July 15, 2015 at 11:56 am #20185
              fleetwin
              Participant

                US Member - 2 Years

                Well, sure hope it is all set. But, you may want to run the engine a few times, then pull the thermostat cover again to check for more impeller carnage.

                July 19, 2015 at 10:07 pm #20414
                flathead
                Participant

                  Thought I’d update the progress. I put the new core plug in, same result. So I pulled the head, found 2 pieces of impeller in the channel of the head. So now I’m waiting on a new head gasket. Hopefully this will be the cure. It’s been a battle so far. While I have the head off, is there anything I should do? Any other places I should look for rubber? There is some scoring in the cylinder walls, I’d assume some would be normal for a motor this old? Like I said before, the motor runs nice. Is there anything special I have to use to clean the head/block surfaces? How about sealant, what should be used on the head gasket? Thanks again for the help.

                  July 19, 2015 at 11:05 pm #20420
                  fleetwin
                  Participant

                    US Member - 2 Years

                    Boy, this is a tough one. Impeller chunks could be stuck anywhere, including in the exhaust housing/water tubes. Do your best to check every passage possible while that head is off. What do you mean by "the channel of the head"? Is this a spot that could have stopped water flow?
                    I know you have probably answered this, but have you run the engine with the thermostat cover removed after the engine stops pumping/overheats? I keep asking this only because having a definite answer might help direct you/us to the problem area.
                    In other words, if no water is coming out of the thermostat cup when/after the engine overheats, that would direct us toward the exhaust cover/water tubes or areas before the thermostat. But, if there is plenty of water flow at the thermostat cup right after overheating, I would be looking for problems after the thermostat. I realize this testing scenario is imperfect, because the impeller chunk might dislodge after shut down giving inconclusive/false test results. But, if you see the water flow stop after pulling the cap, that will say something. You may be able to loosen the screws once the motor starts to overheat without stopping it, which might minimize false conclusions.
                    Hopefully Frank/Garry will weigh in more on this.
                    In any event, use a little gasket OMC/merc gasket sealer on both sides of the head gasket. Be sure to check the block and head for flatness as well.
                    Hold off on reinstalling the head until we have heard from others, sure don’t want you to be forced to pull the head again after you have reinstalled it.

                    July 19, 2015 at 11:30 pm #20423
                    flathead
                    Participant

                      I have pulled thermostat after it heats up. It blows water out the cap. The channel I mentioned is I assume, a water passageway around the head. It looks like an 8. The rubber was in the bottom of the 8. If that is a water passage, there is no way it wasn’t restricting water flow. I’m not sure that’s the only place, but it was one place anyhow. Also there was a piece I found earlier in the bottom hole that Frank mentioned, behind the core plug. Is there a problem using carbkleen type spray to clean it up before installing new gasket?

                      July 20, 2015 at 8:21 pm #20481
                      fleetwin
                      Participant

                        US Member - 2 Years

                        Unfortunately, I’m not understanding your description of where the impeller chunk was lodged. perhaps you can post a picture.

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