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2004 Mercruiser 6.2 repower

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  • 2004 Mercruiser 6.2 repower

    Buddy's SeaRay 270SD has a 6.2 MPI/B3 setup.

    he was out about a month ago and it wouldnt start when he was going to leave the Bar/Restaurant on the water.

    he thought it was a bad starter. called Sea Tow, had his boat towed to his mobile mechanic. I asked if he was hydro locked or not, he said didnt think so, however mechanic would be looking at it.

    the mechanic was busy and didnt get to the boat for about 4 weeks.

    turns out it was hydro-locked.

    and it sat......

    and now it wont turn over.

    He was quoted 12k for a new motor

    Having the buddy work with the mechanic on deals, however i told him to get the motor yanked, a Michigan Motorz long block would be so much cheaper.

    however he keeps asking if I would help him build a motor as he knows I have built a few strokers.....

    Just awaiting the serial number to know what ECM is in there, and to determine which heat exchanger i will be putting on the motor. in addition to closed cooling, I plan on stainless risers.

    Who does the best job at re-flashing the stock ECM's ?

    I will be changing the cam profile, the intake runners, porting the heads, and changing slugs. So I will need an appropriate tune.

    RPM will be higher, torque band will be fatter.

    Pictures will ensue..... Motor coming out today, should be on engine stand by weekend.
    Last edited by Scott Danforth; August 14th, 2019, 06:42 PM.
    Cheesehead boating the Gulf Coast of FLA 27.51° N, 82.53° W

    1988 Cruisers Rogue 2420 -VP 290 DP now powered by custom 468 - https://forums.iboats.com/forum/owner...988-rogue-2420

    Past Boats
    1970 Wooster Hellion - Merc 9.8
    2002 SeaRay 190BR - 5.0 - A1G2 - "Cheeseheads in Paradise"
    1984 Avanti 170DLI -3.0 stringer- "Ship Happens"

    What’s behind you doesn’t matter.Enzo Ferrari

  • #2
    Who does the best job at re-flashing the stock ECM's ?
    Ayuh,..... Donno, but I'll be watchin',.......

    Comment


    • #3
      Who does the best job at re-flashing the stock ECM's ?
      I read the question but the answer is and is not simple. Being a 2004, I'm thinking 555 ECM and don't know of anyone that can do that. If its a MEFI then that can be done.

      OBD can reflash and tweek the tune for more HP. Wipple has different stage tunes and some like them. It actually comes down to the best tune is the one that is done on the motor.

      If its a MEFI, then pick up MEFI burn SW, AFR meter and O2 sensors

      94 Formula 27PC Custom 509MPI MEFI3 , B3 XR
      95 Rinker 232 w/ 7.4L Carb 0F425011 B1 0F486471
      07 Seadoo GTX
      Merc Adults Only VP Adults Only
      G-Dad always said "First Liar doesn't stand a chance"

      Comment


      • #4
        Thanks AD.... Been asking for serial number for the past day.

        Buddy will be in Miami tomorrow, so hopefully the shop mechanic calls him with serial number.
        Cheesehead boating the Gulf Coast of FLA 27.51° N, 82.53° W

        1988 Cruisers Rogue 2420 -VP 290 DP now powered by custom 468 - https://forums.iboats.com/forum/owner...988-rogue-2420

        Past Boats
        1970 Wooster Hellion - Merc 9.8
        2002 SeaRay 190BR - 5.0 - A1G2 - "Cheeseheads in Paradise"
        1984 Avanti 170DLI -3.0 stringer- "Ship Happens"

        What’s behind you doesn’t matter.Enzo Ferrari

        Comment


        • #5
          Was it salt water Scott ? Is it defo a write off ? I’ve known loads of GM engines to take in water and survive it easily after a few oil changes. You know what caused the ingress ? The 6.2 to me has always seemed a little bit pointless. I’m amazed it was even allowed production being so close in power to the 350 mpi in power. Suppose like all strokers, it will have a little more torque. I’m now wondering if the ecu is even different from the 350. Certainly the 350 has a different ecu from the 305 mpi. Not sure about the 383.

          Comment


          • #6
            Stock 377 (6.2) is 320hp vs the 350 (5.7) at 300hp

            A very mild build.

            370hp is easy with a cam change, 420hp is easy with a bit of porting, increase in plenum volume and a few more RPMs

            Not sure what lead to the water ingress. My guess the dry joint exhaust manifolds rusted thru
            Cheesehead boating the Gulf Coast of FLA 27.51° N, 82.53° W

            1988 Cruisers Rogue 2420 -VP 290 DP now powered by custom 468 - https://forums.iboats.com/forum/owner...988-rogue-2420

            Past Boats
            1970 Wooster Hellion - Merc 9.8
            2002 SeaRay 190BR - 5.0 - A1G2 - "Cheeseheads in Paradise"
            1984 Avanti 170DLI -3.0 stringer- "Ship Happens"

            What’s behind you doesn’t matter.Enzo Ferrari

            Comment


            • #7
              Originally posted by Scott Danforth View Post
              Stock 377 (6.2) is 320hp vs the 350 (5.7) at 300hp

              A very mild build.

              370hp is easy with a cam change, 420hp is easy with a bit of porting, increase in plenum volume and a few more RPMs

              Not sure what lead to the water ingress. My guess the dry joint exhaust manifolds rusted thru
              Not so good if it’s salt.
              Yeah. Only 20hp difference between the mpi 350 and 6.2. I’ve a cam in my mpi...I’m not sure it’s suited at all. Runs a bit lumpy low down the rpm and only really works at high rpm. Pretty sure it’s down to the fuelling not being able to be adjusted with that ecu. Always going to be a hit or a miss I’d think.

              Comment


              • #8
                Serial number is 0M604738

                these are the ECM's listed

                Click image for larger version

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                looks like the 555.....

                also looks like Hardin Marine offers custom tunes
                Cheesehead boating the Gulf Coast of FLA 27.51° N, 82.53° W

                1988 Cruisers Rogue 2420 -VP 290 DP now powered by custom 468 - https://forums.iboats.com/forum/owner...988-rogue-2420

                Past Boats
                1970 Wooster Hellion - Merc 9.8
                2002 SeaRay 190BR - 5.0 - A1G2 - "Cheeseheads in Paradise"
                1984 Avanti 170DLI -3.0 stringer- "Ship Happens"

                What’s behind you doesn’t matter.Enzo Ferrari

                Comment


                • #9
                  Yep that's a 555
                  94 Formula 27PC Custom 509MPI MEFI3 , B3 XR
                  95 Rinker 232 w/ 7.4L Carb 0F425011 B1 0F486471
                  07 Seadoo GTX
                  Merc Adults Only VP Adults Only
                  G-Dad always said "First Liar doesn't stand a chance"

                  Comment


                  • #10
                    Looks like your correct with the 555, even OBD is now saying they can do it

                    https://obd2allinone.com/mercecms.asp
                    94 Formula 27PC Custom 509MPI MEFI3 , B3 XR
                    95 Rinker 232 w/ 7.4L Carb 0F425011 B1 0F486471
                    07 Seadoo GTX
                    Merc Adults Only VP Adults Only
                    G-Dad always said "First Liar doesn't stand a chance"

                    Comment


                    • #11
                      Pictures of carnage......

                      Andrey picked up the motor.....

                      Dave looked in the bores with a bore scope.....rust..... and what we will refer to as "fish sauce"

                      so off comes the Starboard side manifold.

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                      all 4 cylinders on port side were full of water

                      Keep in mind..... this is a dry-joint manifold installation with 3" risers..... and the dreaded "single point drain"

                      going to look at the manifold closely, however going with HX cooling and most likely aftermarket manifolds



                      Dave and Andrey removed the T-stat assembly and lower plumbing nightmare which was much of the single point drain.

                      all the block drain lines were plugged, most of the manifold drain lines were half plugged with debris

                      this is the factory nightmare plumbing by Mercruiser. only 6 hoses would be required if they gave up the single point drain concept. and there would not be busted blocks thru-out the world


                      The e-coated lower intake manifold is rusty. It could be sand blasted, welded, epoxy painted for a whole lot less than the $950 price. However depending on what Andrey wants for power level, it may end up with an RPM air-gap modified for injectors

                      there is the start of a milk shake in the oil, so the manifold had been leaking for a bit

                      it simply let go when the boat was shut off while hot

                      and filled all the cylinders with water

                      Had the mechanic looked at it when it was first towed in, the motor would still be running. however after a month of sitting with salt water.... not so much.

                      Click image for larger version

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                      Back to the fish sauce.....

                      notice the emulsion of stuff in the bores..... a mixture of sea water with a heavy dose of algae, oil, rust and aluminum corrosion..... while attempting to get the pistons to move with a dead blow..... we were covered with what Andrey and Dave are now calling "Fish Sauce"

                      This motor is a core..... at best

                      Now for the choices

                      option A - stock long block and new manifolds - lowest cost and fastest back on the water
                      option B - stock long block, HX cooling, revised plumbing - about $1000 more than option A, however not dealing with the single point drain and the rusty manifolds...... priceless.
                      option C - New GMPP block, new GMPP vortec heads, SCAT cast rotating assembly, coated clevite bearings, Comp Cams / Hardin cam setup, HX, mild bump in RPM to 5500..... about 380 prop HP
                      option D - Option C with Forged internals and a lot more fueling..... and the RPM limit raised - about 420prop HP

                      late yesterday option E presented itself.... a factory reman Mercruiser 6.2 with Fresh Water cooling for about the price of option B....


                      Will keep y'all posted....
                      Attached Files
                      Cheesehead boating the Gulf Coast of FLA 27.51° N, 82.53° W

                      1988 Cruisers Rogue 2420 -VP 290 DP now powered by custom 468 - https://forums.iboats.com/forum/owner...988-rogue-2420

                      Past Boats
                      1970 Wooster Hellion - Merc 9.8
                      2002 SeaRay 190BR - 5.0 - A1G2 - "Cheeseheads in Paradise"
                      1984 Avanti 170DLI -3.0 stringer- "Ship Happens"

                      What’s behind you doesn’t matter.Enzo Ferrari

                      Comment


                      • #12
                        forgot to mention..... the plastic dizzy is broken....Mercruiser wants $900 for a $65 GM dizzy
                        Cheesehead boating the Gulf Coast of FLA 27.51° N, 82.53° W

                        1988 Cruisers Rogue 2420 -VP 290 DP now powered by custom 468 - https://forums.iboats.com/forum/owner...988-rogue-2420

                        Past Boats
                        1970 Wooster Hellion - Merc 9.8
                        2002 SeaRay 190BR - 5.0 - A1G2 - "Cheeseheads in Paradise"
                        1984 Avanti 170DLI -3.0 stringer- "Ship Happens"

                        What’s behind you doesn’t matter.Enzo Ferrari

                        Comment


                        • #13
                          Option E has a three year warranty ?

                          Comment


                          • #14
                            Option F - Holley Sniper w/D
                            94 Formula 27PC Custom 509MPI MEFI3 , B3 XR
                            95 Rinker 232 w/ 7.4L Carb 0F425011 B1 0F486471
                            07 Seadoo GTX
                            Merc Adults Only VP Adults Only
                            G-Dad always said "First Liar doesn't stand a chance"

                            Comment


                            • #15
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                              Originally posted by Scott06 View Post
                              Option E has a three year warranty ?
                              Not sure
                              Cheesehead boating the Gulf Coast of FLA 27.51° N, 82.53° W

                              1988 Cruisers Rogue 2420 -VP 290 DP now powered by custom 468 - https://forums.iboats.com/forum/owner...988-rogue-2420

                              Past Boats
                              1970 Wooster Hellion - Merc 9.8
                              2002 SeaRay 190BR - 5.0 - A1G2 - "Cheeseheads in Paradise"
                              1984 Avanti 170DLI -3.0 stringer- "Ship Happens"

                              What’s behind you doesn’t matter.Enzo Ferrari

                              Comment

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