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    My first dumb question on the forum

    Lol and probably more to come. New to owning my own boat, but I'm mechanically inclined and take on most projects. So here goes for the first.

    Ok I replaced the raw water pump and have only had it on the water once. It ran a little warm (88 merc 7.4) at lower RPM running 175 under load getting up to about 185-190 ish hard to tell on the type of gauge (on the list to replace). So got it home and thought it would be a good idea to flush the block. Pulled the plugs and don't think it had ever been done before lol. Went to run with cleaner in block and couldn't get it to pick up any water from the hose. So pulled hoses from pump and ran water through them just to make sure everything is clear. And it was. Ordered a new pump right away... Lol Amazon 1-2 day shipping today is more like 4-7 day... So new pump won't be her until Monday. Pulled pump today to check it out and it's a little chewed up, but far from destroyed.

    Now the question. Can I flip the impeller? The other side of the lands are in much better shape.

    Last weekend before the grandkids head back out of state and they had a blast last weekend. So kinda hoping to mcgiver something. Lol

    Thanks in advance for any thoughts on this.

    #2
    The only dumb question is the one you don't ask. Lots of great people here willing to help.
    Rick Grew

    1981 Carver 3007 Aft Cabin

    2004 Past Commodore
    West River Yacht & Cruising Club
    www.wrycc.com

    Comment


      #3
      Going to give it a try... Lol all I have accomplished so far is inventing new four letter words... Lol

      Comment


        #4
        I don’t recommend flipping the impeller. There is a risk of it breaking up altogether. My suspension is that the exhaust manifolds and risers are getting blocked with rust. You can usually pop the risers off and get a good look at the inner water jacket. I’m guessing this is a partial closed cooled engine using coolant and a heat exchanger. If it has cooing hoses going directly to the risers, it’s a fully closed system and there is a block off plate between the manifold and the riser. Look very specifically at the point where the water jacket effectively ends and dumps the water into the exhaust. That’s usually where things clog first. You should be able to put your hand on any part of a partial closed cooled manifold and have it only feel slightly warm. Risers should be less than a hot tub.
        Note the position of the hose clamps on the exhaust riser. They should be 180 degrees opposite and opposing directions, so you should be looking at the slot/hex end of the hose clamp.
        P/C Pete
        Edmonds Yacht Club (Commodore 1993)
        1988 3818 "GLAUBEN”
        Hino EH700 175 Onan MDKD Genset
        1980 Encounter Sunbridge "Misty Blue" (Sold)
        MMSI 367770440
        1972 Chevrolet Nova Frame off Resto-mod in the garage
        Boating on the Salish Sea since 1948

        Comment


        • Gsherwood
          Gsherwood commented
          Editing a comment
          “Pop them off” hah! 😄

        #5
        Well with that said I'm definitely going to grab some pics!!! Lol

        Comment


          #6
          After re-reading yes it is as you guessed.... With a heat exchanger....

          Comment


            #7
            In my opinion flipping the impeller may be tried as an experiment just for a test or a short while but should not be used as a "solution". The impeller wings bend in a certain direction which is cruicial for proper operation. When you turn them around they may not function as planned and also the wings may break.
            Retired, computer expert / executive
            Bayliner 285 Cruiser / Mercruiser QSD 4.2L 320 HP Diesel
            Live in the Bay Area, CA, USA, boat in Turkey
            D-Marin @ Turgutreis in Bodrum/Turkey
            [email protected]
            [email protected]

            Comment


              #8
              .........................
              Originally posted by Desert boat View Post
              ............... . Pulled pump today to check it out and it's a little chewed up, but far from destroyed.

              Now the question. Can I flip the impeller? The other side of the lands are in much better shape.

              So kinda hoping to mcgiver something.

              Of all the things to NOT mcqiver, this is at the top of the list!
              In other words, DO NOT flip the impeller over and run it.... even for a short duration!
              The blades have no doubt taken a "set" by now, and will not undergo the stress of being folded over and forced to run in the opposite direction of rotation.
              Some of them will most likely break off.
              If they were to break off, they will become lodged within the seawater path.
              If so, you will be spending unnecessary time trying to retrieve all of the pieces.

              Rick E. Gresham, Oregon
              2850 Bounty Sedan Flybridge model
              Twin 280 HP 5.7's w/ Closed Cooling
              Volvo Penta DuoProp Drives
              Kohler 4 CZ Gen Set

              Comment


                #9
                Let's see the impeller ... Running at 190 is not that bad if it was 200 is a no no.

                What drive ?

                You tried back washing, pull the hose that brings lake or sea water in from the drive, backwash place the drive in a bucket or trash can or have some watch what comes out.

                I am a little confused " changed the raw water pump "

                P.S can't wait to get my grandkids on a boat, and teach them fishing I am jealous .

                Shoot me a email [email protected] include your cell number or I'll send you mine, 5 minutes on the phone beats a 100 posts I just helped a guy in Cali on the phone, he found me thru another website from years ago posting there.
                Be good, be happy, for tomorrow is promised to no man !

                1994 2452, 5.0l, Alpha gen. 2 drive. Sold ! Sold ! Sold !

                '86 / 19' Citation cuddy, Merc. 3.0L / 140 hp 86' , stringer drive. Sold ! Sold ! Sold !

                Manalapan N.J

                Comment


                  #10
                  Did you perform a flow test at the thermostat housing to see if the engine is getting proper flow? I/O? If so what drive?
                  1997 Maxum 2400 SCR 5.7LX Bravo II

                  Mike

                  Comment


                    #11
                    What drive ?
                    Originally posted by Desert boat
                    (88 merc 7.4)...................................... So pulled hoses from pump and ran water through them ..................
                    From the above comments, me thinks Bravo drive with engine mounted seawater pump!
                    Rick E. Gresham, Oregon
                    2850 Bounty Sedan Flybridge model
                    Twin 280 HP 5.7's w/ Closed Cooling
                    Volvo Penta DuoProp Drives
                    Kohler 4 CZ Gen Set

                    Comment


                    • Nauti_Mike
                      Nauti_Mike commented
                      Editing a comment
                      I was thinking it’s a Bravo and may have a cooling restriction in the transom water hose but a lot of 7.4s were still mated to Alphas in the late 80’s

                    #12
                    Okay so first thanks everyone for your support and help. Glad I found a community like this one.

                    So here is where I'm at. I'm going to put it back together as it should be, but will do that when I get to the lake. Like 15deg cooler there... Chief I will be shooting an email!!! Thanks again everyone!! Will keep everyone posted as to how it goes.

                    Comment


                      #13
                      Ok wanted to update from last weekend and say thanks again!!!
                      think I have narrowed it down... Seems to only overheat when I'm trimmed up. Not sure if something is getting kinked or what, but have plans on pulling the drive this winter and going through it. Definitely needs a recoat before it ever sees salt.

                      Comment


                        #14
                        Interesting, only overheats when trimmed up? So I’ll assume your up on plane running around 3600 rpm, trimmed up a bit to find the sweet spot. It’s possible the water hose from the bell housing to the gimbal housing has become compromised and is sucking air. I’d say if a drive service has not been done in the last 4-5 years it’d be a good idea to do so.
                        Dave
                        Edmonds, WA
                        "THE FIX"
                        '93 2556 5.7 Bravo II 2.0:1 18 1/4x19 P
                        (.030 over-Vortec top end-part closed cooled)
                        The rebuild of my 2556 https://www.baylinerownersclub.org/f...76?view=thread
                        Misc. projects thread
                        https://www.baylinerownersclub.org/f...56-gctid789773

                        Comment


                          #15
                          Yeah as normal I should be more clear... When going slow in shallows. Like loading on the trailer...

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