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Volvo Penta 7.4gl 1995 Water in Oil

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  • #16
    A couple of other things I noticed...
    has this engine ever been apart? I saw an '.040' stamp on one of the pistons suggesting it may be a reman engine...
    for a raw water cooled engine there is not much rust at all in the cooling ports, mostly black carbon it looks like, wonder if somehow oil was als getting into the cooling water, usually on an engine used in salt you see a lot of rust build up in the block and cyl head cooling passages, in fresh water some light surface rust. I don't see that much there unless its under that black/carbon looking coating...
    the rusty deposits in the cam valley and round the hydraulic lifters look like they have been there a long time...
    your exhaust manifolds and elbows, were there any rust trails emanating from the joint between the 2 where the gasket is? I don't really see evidence from the pix of water stains/rust inside the center exhaust gas passage.
    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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    • #17
      Hey Lou, thanks for the suggestions. All the water passages are filled with thick carbon. It chips away with a flathead screwdriver. I ended up shopvac-ing as much as I could and chipped away as much as I can, but still no rust present in water jackets.

      I did the leak test with acetone. Plugged it up and filled from the top and let it sit there all day, and not a single leak. The liquid line stayed the same and I couldn't find any wet spots on both exhaust manifolds. I did however find some rust inside in some areas of the exhaust manifold, almost as if suggesting water passed through. But mostly black carbon. The gaskets between the riser and manifold looked clean, no rust. The water jackets of the exhaust manifolds and risers on both sides are a bit rusty.

      Side note, I ended up finding a busted spring on my starboard side, 5th cylinder intake valve. Not sure if this is related to the whole water scenario, but maybe water was in the cylinder and broke the spring.

      I'm just not sure if I should drop a few hundreds to replace all manifolds and risers since they're not leaking now.

      I'm really wondering if the intake manifold gaskets we're to blame for all this mess, because the gaskets themselves were rusty, crunchy and deteriorated. Rust everywhere on the intake manifold to the point where a hole rusted through. Maybe the water was leaking into the cam valley and that's the source of the milkshake. I don't know, what do you guys think?


      ​​​​

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      • #18
        Salt or fresh water use? If they pass the acetone test and the sealing surfaces clean up well and are flat to less than .003” then you could use them. The rust you see could be condensation since these probably run pretty cool. I would get the heads checked out by an automotive machine shop esp if used in salt water.
        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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        • #19
          Yes the engine has been used for saltwater. Surfaces cleaned up pretty good for the exhaust manifold and riser. Ill keep ya guys posted on the work being done. I think i'll check out the heads next. Otherwise i'm pretty much ready to throw everything together with fresh gaskets and hope for the best.

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          • #20
            When you take the heads to the machine shop make sure to tell them that they were from a boat used in salt water and look for corrosion in the water passages, because it is possible for them to rust through near the valve seats and that would let water in a cyl and hydrolock the engine, NO GOOD! Judging on the condition of your block and exhaust manifolds they maybe fine, might just need a freshening up.
            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"

            Comment


            • #21
              Thanks for the tip. Looking into a shop that will clean and magnaflux them, as well as check the surface and vacuum check the ports for $52 for the pair of heads. Seems like a decent price.

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              • #22
                Heads got back from the machine shop. No cracks, no rust, and surface is flat. Water jackets not leaking. All is good with the heads. Going to start rebuilding in the next week i'll keep you posted if anything comes up. Hoping that all of this was just bad gaskets.

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                • #23
                  Well that's good news! Get a nice Fel Pro marine gasket set for the head gaskets and intake and some good exhaust elbow gaskets. Also a thread chaser to clean out the bolt holes in the block and exhaust manifolds. If the head bolts are corroded I'd replace them, I used ARP bolts when I did mine.
                  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"

                  Comment


                  • #24
                    Hey guys,

                    Still rebuilding here. I decided to slap on a nice coat of paint before proceeding with the rebuild.

                    ​​I was looking through my pictures, and stumbled across this one when I removed the head gaskets. Rightmost cylinder water jacket, I'm noticing a rust spot that runs almost to the cylinder. You guys think this was the cause of the water in oil?

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                    • #25
                      the right most cylinder had water sitting in it (witness marks on the piston) and the bore has rust. that would indicate that motor had water coming in the exhaust, then into the cylinder head then into the oil

                      other than that, dont see what you are looking at. you need to clean up the deck surface
                      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

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                      • #26
                        Are you referring to the rust stain round the upper right side water passage? While that's a stain there it's hard to say if water came in that way. Usually when head gaskets are blown and allowing in water, the fire rings are split or there is a gap you can see in them. On mine when I pulled off the OE HGs, the fire rings were split on both cyls that leaked water. Most likely it was a previous overheat.
                        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"

                        Comment


                        • #27
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                          What actually does look suspicious to me is in that right hand side cylinder, the HG at the 3:00 postion….looks like it was starting to distort there....
                          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"

                          Comment

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