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2018 df30a cooling system issue...

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  • 2018 df30a cooling system issue...

    Hi everyone, new member here.

    I have a 2018 DF30A and seem to be having an issue with the cooling system.

    Does anyone know if the impeller should immediately start pumping water out of the pilot hole when the engine is cranked? Or, is there a thermostat?

    My outboard has seen very little use, probably only 40 hours or so in the last 3 years, since new. Since day-one, the pilot hole would sometimes discharge water immediately at start-up, and sometimes only after what seemed to be a warm-up period. Is there a thermostat on this model?

    Today, I cranked it up after sitting in my garage for about 4 months to run fresh gas through it (non-ethanol of course) and after a couple of minutes the high temp lamp came on and I noticed the pilot hole was only BARELY dribbling water. I immediately shut it down. I hooked up the water hose to the flush port on the side and water came shooting out of the pilot hole, so I know it's not plugged.

    Also, is the pilot hole the ONLY location that water should ever be discharging from the motor package? I ask, because on more than one occasion I noticed a small amount of water seeming to leak from the lower motor cover(?) that goes over the mid-section (red circle in attached drawing). If this should not be happening then it seems I have a gasket issue or something else not right in the mid-section. I never really questioned or panicked about this because it did this from day-one when it was brand new.

    Should I take it straight to the dealer (authorized repair center from what I understand), or is the lower unit fairly easy to remove to see what's going on in there? Any input is appreciated.

    Also, I have a Suzuki extended warranty that is good for another two years, and with only a $25 co-pay I may just take it to a dealer to get checked out.


    Outboard Diagram.jpg

  • #2
    Water should come out the tell tale very shortly after starting, mine is within 15 seconds or less. The only purpose of the tell tale is to verify the water pump is pumping water. The thermostat should be closed when starting(cold) but the telltale should have a strong stream with the thermostat open or closed. My guess is the impeller has sat too long and has deteriorated. Impeller replacement won’t likely be covered by warranty, it’s not a big job for a DIY. The bottom of your circle is about where the top of the water pump sits which will be flooded with water when running. When you pull the boat out of the water all that water will drain. Your circle is drawn a bit too high compared to my engine for water draining so I’m sure what to tell you.


    • #3
      I agree with Murray - one of the worst things for impellers is to sit, dry, unused for long periods. I know a guy who put a new water pump in and then didnt use the motor for 2 years, and then had to replace it again. They dry out, get a “set” in the vanes, and dont pump effectively.

      Do a full water pump kit, not just the impeller. While you are doing it, drain and refill the gearbox oil, and use new washers on the plugs.


      • #4
        I was hoping Moonlighter(or someone else) would have commented on water coming from the mid unit since I’m not sure how to answer that question. I’m fairly certain that water should not be coming from the area circled. On mine, running on muffs I have water coming from the telltale and the prop only. If you are sure you have water coming from the mid unit area or above it might be worth your while to remove the side covers and run it on muffs to investigate further.


        • #5
          Thanks for the info. I removed the lower unit this morning (easy enough, good ol' YouTube) and found a couple of impeller vanes had broken off and the impeller definitely needs to be replaced. Even though the gasket looks fine, I ordered the complete kit.

          One thing I noticed and found a little odd is the impeller shaft is a little offset in the chamber. I know the engineers obviously designed it this way for a reason, but just looks a little odd with more pressure being put on the vanes in one area of the rotation than the other. Oh well...

          Thanks again for the info.





          • #6
            The offset in the pump is exactly how it is supposed to be. Otherwise, pump no worky.

            Once you install the new water pump kit, if testing in a barrel of water, make sure you submerge the leg nice and deep - At least to 3-4” above the cav plate is necessary to get the water pump primed up.


            • #7
              I have a DF25A - basically the same motor. It DOES have a thermostat, but should pee regardless of whether the thermostat is open or closed. At the end of my first season, my motor started overheating when I let it idle for more than a couple minutes. As soon as I ran the RPM to about 2000 it would cool down and run fine. I removed the impeller and found that mine looked about like yours, with 2 of the vanes broken. I believe this happened because the first time I started the motor was in my driveway, in a bucket of water. I had the motor submerged such that the water input grates were beneath the water, but I didn't realize the water needs to be several inches higher to "prime the pump". Now that you've removed your impeller, you see that it sits above the "cavitation/ventilation plate". The water level must be above the impeller in order for the impeller to begin pumping. When I first started my motor, it did not pee. I let it idle for about 30 seconds, wondering just as you were if the thermostat needed time to open. I now believe that 30 seconds of dry running is what broke my impeller.

              The main problem I see with your impeller in your photos is one of the vanes is pointing the opposite direction as the others. That is not right! All the vanes must point in the correct direction. The offset center shaft is the basis for this type water pump. The water comes into the pump on the "big" side the volume enclosed between the vanes is large. The outlet is on the "small" side of the pump, where the size of the enclosed area has been compressed to a smaller volume, increasing its pressure.

              You don't say how you were providing water to the motor - whether in a bucket or with muffs. You cannot use the flush port to run the motor. When you run water into the flush port, it will run out all over the motor.


              • #8
                Wonder where the missing segments are?


                • #9
                  Yes, I worried about the same thing with my motor. I did remove the thermostat, hoping to find some of the missing parts there. But I found nothing. I never have found any of the missing parts. I can only hope the rubber wore away gradually, rather than in large chunks.


                  • #10
                    Thanks for the info. Regarding noticing one of the vanes was not bent in the same direction as the others is of my doing. I removed the impeller earlier and then re-inserted it into the chamber for the picture and didn't notice one of the vanes was not seated properly. When originally removed from the chamber, the vanes were definitely all in the same direction.

                    Also, regarding the missing segments, there was one piece still in the chamber. It's about half the size of a tic-tac and obviously half of the missing segment of one of the vanes. So, I probably have either three smaller pieces, or one large and one small piece somewhere in the system. I purchased a service manual when I got the motor, and it has a pretty good flow diagram of the cooling system. I'll start there and see if I can find the other pieces fairly easily at first by flushing them out. These pieces are definitely too big for the pilot tube, so they are possibly still in the system somewhere.

                    Or, now that I look at the flow diagram, I guess it could have been possible for the pieces to work their way all the way through the system and out the prop exhaust.



                    Last edited by timothy585; 07-05-2021, 09:33 AM.