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Mercruiser 4.3lx - Water in oil pan and milky oil

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  • Mercruiser 4.3lx - Water in oil pan and milky oil

    Hey guys, have done lots of reading about people with similar issues and I've read the traditional cracked block, leaking exhaust manifolds/risers, blown head gasket, etc... Well before I made this post I tried to narrow it down as much as possible for you guys and did lots of digging into it last night. Here it goes:

    Motor Serial #D810408, 4.3LX 4 barrel carb.

    The boat came out of storage this week after it sat for 2 years without any use... I went to drain the oil from the oil bolt on the pan and a good chunk of water came out and then oil. I went ahead and then removed the spark plugs, and they all looked similar (photo attached). But I did have some water come out of cylinders #3 and #6. Then I removed the port side riser and manifold and didn't see anything obvious (photos attached) then the same for the starboard side (photos attached). Since I didn't see anything obvious here, I decided to go ahead and remove the intake manifold so I could check the underside of it and I've also attached photos here. I don't see any crack in my block, nor in the intake manifold. Unless I am missing something?

    I feel like I may be looking at something else... head gasket? Oil Cooler? Maybe just a failed gasket?

    Sorry for all the photos - I'm mechanically inclined but when it comes to diagnostics... I fall short

    Any input is appreciated - I know some of the gurus will chime in and help me solve this! I also plan to update this thread when it does get fixed so many people can find their answers based on my issue!

  • #2
    Not seeing any signs of how water entered. Rain water maybe?

    With water sitting in motor for 2 years (and 2 cylinders), probably needs a rebuild
    94 Formula 27PC Custom 509MPI MEFI3 , B3 XR
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    07 Seadoo GTX
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    • #3
      If it sat 2 years or any length of time with water in cylindesr those are now damaged and motor in need of overhaul. Also the 4.3 like to freeze and crack underside of intake manifold,.
      When in doubt,Trim it out!!!
      Business Owner & Certifed Technician
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      • #4
        Originally posted by alldodge View Post
        Not seeing any signs of how water entered. Rain water maybe?

        With water sitting in motor for 2 years (and 2 cylinders), probably needs a rebuild

        Hmm. Based on the amount of water... I wonder how it could be rain water. Only thing I can remember is getting to the cottage one weekend and the boat was filled at the back because the bilge failed. I wonder if that had anything to do with it but don’t see how that much water could get in to the engine even so. Do I have a chance of swapping a gm 4.3 into it?

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        • #5
          Originally posted by Faztbullet View Post
          If it sat 2 years or any length of time with water in cylindesr those are now damaged and motor in need of overhaul. Also the 4.3 like to freeze and crack underside of intake manifold,.
          I’ll have to check this thoroughly. I attached two pictures of it but maybe something more under that plate?

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          • #6
            The manifolds and elbows don't look like they were leaking and the intake manifold does not have the rust trails in the intake ports you'd expect either, if water got in high enough I guess it is possible to get in the pan, but in the cyls, that would have to be really high like enough weight to tip the trailer up. Oil is for sure milky though, was the engine winterized promptly? Cracks you'd see on the outer surface of the block (like in front of the starter and in front of the oil filter mount) and on the inner surfaces of the block in the cam valley, about an inch or so below the block deck.
            Water can enter from a cracked cyl head, block, failed head gasket, faulty exhaust or bad intake gaskets, as well as via the carb if the engine is left out in the open.
            1988 Four Winns 200 Horizon
            4.3 OMC Cobra

            98 Jeep Grand Cherokee 4.0 Selectrac
            07 Jeep Grand Cherokee Limited 5.7 Quadradrive II

            "While air doesn't freeze....rust never sleeps"

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            • #7
              Originally posted by Lou C View Post
              The manifolds and elbows don't look like they were leaking and the intake manifold does not have the rust trails in the intake ports you'd expect either, if water got in high enough I guess it is possible to get in the pan, but in the cyls, that would have to be really high like enough weight to tip the trailer up. Oil is for sure milky though, was the engine winterized promptly? Cracks you'd see on the outer surface of the block (like in front of the starter and in front of the oil filter mount) and on the inner surfaces of the block in the cam valley, about an inch or so below the block deck.
              Water can enter from a cracked cyl head, block, failed head gasket, faulty exhaust or bad intake gaskets, as well as via the carb if the engine is left out in the open.
              Thank you for that info... I’m curious at this point so I’m gonna go ahead and remove the heads and check head gaskets as well as the heads them selves. Maybe this is simple error and it’ll bug me until I know !

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              • #8
                before pulling the heads (its rarely ever the head gasket)

                do a pressure test of the cooling system.
                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

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                • #9
                  Originally posted by Scott Danforth View Post
                  before pulling the heads (its rarely ever the head gasket)

                  do a pressure test of the cooling system.
                  What he said!!!

                  Once you disassemble it is too late to pressure test and find out if you have a cracked block. I did that once. It worried me constantly during the rebuild whether I missed anything.
                  17 Foot '90 Bluewater
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                  • #10
                    Agreed the only reason to suspect the HGs would be if you had a bad overheat in the past. Sometimes they will last a few more seasons and then one day you wind up with water in a cyl (happened to me!) pulling the heads on these is not a bad job but for sure test it first. The problem is, that your intake is already off!
                    1988 Four Winns 200 Horizon
                    4.3 OMC Cobra

                    98 Jeep Grand Cherokee 4.0 Selectrac
                    07 Jeep Grand Cherokee Limited 5.7 Quadradrive II

                    "While air doesn't freeze....rust never sleeps"

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                    • #11
                      Originally posted by Lou C View Post
                      Agreed the only reason to suspect the HGs would be if you had a bad overheat in the past. Sometimes they will last a few more seasons and then one day you wind up with water in a cyl (happened to me!) pulling the heads on these is not a bad job but for sure test it first. The problem is, that your intake is already off!
                      I know I screwed up taking the intake off.. I read that afterwards. What’s your thought on a potential crack underneath that steel cover on the intake manifold? I can’t see much in that!!

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                      • #12
                        Not likely, the only place in that intake where there is water is the cooling passage right under the thermostat housing that allows water to flow out of the front of each cyl head. That part is at the front end of the intake, you will be able to clearly see if there is a crack in it. The tin plate is there to keep motor oil off the hot center section of the intake because on the older engines there was an exhaust cross over in the intake right under the carb mounting. On the newer Vortec engines there is no exhaust crossoer and no plate.
                        1988 Four Winns 200 Horizon
                        4.3 OMC Cobra

                        98 Jeep Grand Cherokee 4.0 Selectrac
                        07 Jeep Grand Cherokee Limited 5.7 Quadradrive II

                        "While air doesn't freeze....rust never sleeps"

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                        • #13
                          looked at your pix again and blew up the pic of the intake, there is something suspicious there...is that a crack in that smudge or am I seeing things lol?
                          1988 Four Winns 200 Horizon
                          4.3 OMC Cobra

                          98 Jeep Grand Cherokee 4.0 Selectrac
                          07 Jeep Grand Cherokee Limited 5.7 Quadradrive II

                          "While air doesn't freeze....rust never sleeps"

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                          • #14
                            Originally posted by Lou C View Post
                            looked at your pix again and blew up the pic of the intake, there is something suspicious there...is that a crack in that smudge or am I seeing things lol?
                            I see that too! I’m going to investigate that spot tomorrow when I’m home from the cottage. At this point, I’d be ‘happy’ if that was the issue because then I’d know and could sleep!! I’ll report back tomorrow on that spot !! If it is, are those intakes still available?

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                            • #15
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                              Not new but you can find them on eBay. You can also use an Edelbrock aluminum marine intake for this Merc application
                              1988 Four Winns 200 Horizon
                              4.3 OMC Cobra

                              98 Jeep Grand Cherokee 4.0 Selectrac
                              07 Jeep Grand Cherokee Limited 5.7 Quadradrive II

                              "While air doesn't freeze....rust never sleeps"

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