Home Forum Ask A Member 1947 HD-25 Water Pump and Lower Unit oil

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  • #316538
    Mason Bosco
    Participant

      US Junior Member

      I have two questions for yall: What would be the recommended grease for the lower unit? We were thinking that because this old model probably doesn’t seal well that we should try corn grease, or should we do some other grease? Also, this video is terrible because, one, we got a socket on the flywheel nut which is pretty dangerous and two, the gas tank lid is vibrating off, so please don’t mind that… Anyway, we were wondering if the amount of water coming out of the checker looks adequate? The water did get pretty hot but does that look like enough displacement? Thanks!

      IMG_4024-3

      #316560
      JACQUES
      Participant

        download this book print locally to service your HD   Corn head grease is ok for non shifting gear cases but fixing it is a better alternative

        https://www.socalaomci.com/library/johnson_service_manual_10th_edition.pdf

         

        seems to pump ok ..do not run wot in a bucket   aerated  –  churned water does not cool adequatly

        Joining AOMCI has priviledges 🙂

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        #316592
        Sam M.
        Participant

          Canada Member

          Also, this video is terrible because, one, we got a socket on the flywheel nut which is pretty dangerous and two, the gas tank lid is vibrating off, so please don’t mind that…

          Sounds like you’re having fun!

          Check which lubricant is in there at the moment.  If oil drains out, put oil back in.  Oil is the first choice.  If grease is already in there, you have some thinking to do.  Some gearcases have upper bearings that should only be lubricated by oil, not grease.  There is an AOMCI thread about gear grease vs oil that describes this, but I can’t seem to find it at the moment.  If you choose grease, yes corn head grease is suitable.

          For the water flow, yes it looks ok.  Shouldn’t get crazy hot though.  I think on this model it is a rubber rotor behind the propellor (not certain though), so not a concern like an impeller that if you run an old brittle one, a blade may fall off and get stuck your water line, because if the rotor breaks, there is no more pumping pressure to get the broken part stuck!  With an impeller, the other blades can keep pumping and get the broken part stuck.  What I mean to say is, so long as you make sure the water doesn’t stop pumping, you should be ok not replacing your water pump because with it’s location behind the propellor, you’d have to take off the shear pin and then source a new shear pin because those are single use items due to metal fatigue (not the right term) and you don’t want your propellor to fall off because the shear pin was reused and consequently weakened.

          However, if I’m wrong and this motor has an impeller in the standard spot and not a rotor behind the propellor, good job at putting the water level above the impeller for testing!!!  It is an unfortunatly common mistake to have the water level too low and risk impeller damage from dry running it but your water level is good.  Of course, right to the top of the barrel wouldn’t hurt and then there is more water to dilute the motor’s heat too!

          Finally, I don’t see any smoke in your video.  This motor should take 16/1 mix 🙂

          #316599
          Sam M.
          Participant

            Canada Member

            There is an AOMCI thread about gear grease vs oil that describes this, but I can’t seem to find it at the moment.

            Found it!

            https://www.aomci.org/forums/topic/john-deer-corn-head-grease/

            Look at Mumbles’ comment on page 2.

            And take a look at the 90 wt. vs SAE 40 being discussed here:

            https://www.aomci.org/forums/topic/td-20-lower-unit-lube/

            Finding a manual for your motor should clear up the reccomended oil weight for your specific gearcase.

            Another thing to think about is that you can find 90 weight marine gear oil (designed for outboard gearcases) that is intended to deal with water intrusion.  Not sure about finding an SAE 40 oil that can do that.

            #316600
            Sam M.
            Participant

              Canada Member

              Upon further consideration, I don’t think that’s where the water is supposed to be coming out on your motor.  I think there should be a plug there, or else it would spray into the lower cowling when it is installed.  I think the water should exit somewhere under the transom bracket, based on watching a few YouTube videos.  The water is probably getting hot because the motor is getting hot because the water is exiting the system too early and not going through all of the cooling passages it’s supposed to.

              #316614
              Buccaneer
              Participant

                US Member

                My 1950 HD-25 blows water out on the Starboard side
                driveshaft tube, right above the fiber band, via three or
                four holes.

                https://youtu.be/7wmQcVo7R3w

                Prepare to be boarded!

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