Water in oil - 340 with 8.1L

Discussion in 'General Maintenance/Repair Questions' started by Tacoma290, Mar 20, 2023.

  1. Tacoma290

    Tacoma290 Active Member

    492
    Oct 5, 2006
    Tacoma, WA
    340 Sundancer 2007
    Twin 8.1 V-drives
    I am hoping for some advice on the next steps to take. At the end of last year, the engine overheated and the head gaskets failed. Replaced the head gaskets, new oil and filters and put new exhaust manifolds on (see this link, post 22 here: http://www.clubsearay.com/index.php?threads/8-1-low-oil-pressure.110903/page-2#post-1363938 for more details).
    Ran the engine for 8 hours over the winter since the repairs then changed and sampled the oil, and here is the report from Blackstone:
    [​IMG]
    If is seawater, then the likely culprit would be the oil cooler. but isn't the oil in the cooler at a higher pressure than seawater? Am I missing another source of seawater?
    If it is coolant, then either a gasket failed, or we missed a crack in the head, or the block is not happy.
    What is the best way to narrow this down?
     
  2. PlayDate

    PlayDate Well-Known Member

    Dec 25, 2006
    Washington DC
    1994 370 Express Cruiser
    454 Mercruisers
    As you said in the other thread.....it is really difficult to get the water/coolant out of the pan without a few run ups and oil changes.

    The Blackstone numbers are unusually high but that would be the case if there is any sea water left in the pan. As to what to do next.....

    1) Compression check
    2) Look at the plugs for water
    3) Combustion Leak Detector on Closed Cooling tank
    4) Get it hot and change the oil again.

    That should tell us if there is a leak in the combustion chamber. Yes it is possible for an oil cooler to leak sea water into the oil side. They are not that expensive to replace.

    As a baseline did you have Blackstone check the oil on your other engine?
     
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  3. JHornsby3

    JHornsby3 Well-Known Member

    Nov 10, 2020
    Sheridan Oregon
    "Steele'y Tutz"
    1992 300 Sundancer
    Twin 4.3L W/Alpha One Gen II
    Did you run something through the engine to "clean" it after the original intrusion? First thing I have always done was to run a cheap auto trans fluid through an engine to clean out the contamination left behind. I would put, in a 6 plus quart system, two quarts of cheap (walmart brand) oil and top off with auto trans fluid. Run for about a minute or less, letting it circulate through a few times, then drain. Run the low cost oil until the engine comes to temp and drain that. Then run my standard running oil brand. This has always cleaned out the contaminates for me. There will be coolant left behind unless you can clean the system out. PlayDate has things to look at too above.
     
  4. mrsrobinson

    mrsrobinson Well-Known Member SILVER Sponsor

    Mar 9, 2006
    Virginia, USA
    2001 Sea Ray 380DA
    3126 purring CATs
    Especially if you pulled the oil out with a pump and tube down the oil stick tube.
     
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  5. Scott215

    Scott215 Well-Known Member

    622
    Jun 4, 2022
    2006 215 weekender 5.0 mpi
    5.0 mpi alpha 1 gen 2
    I use copper spray on head gaskets when I change them or pull the head
     
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  6. JHornsby3

    JHornsby3 Well-Known Member

    Nov 10, 2020
    Sheridan Oregon
    "Steele'y Tutz"
    1992 300 Sundancer
    Twin 4.3L W/Alpha One Gen II
    I have never used it on a gas engine. But on the high ratio diesels, it's a must. I'm not sure of the 8.1l specs but every older 22:1 diesel, the gaskets don't hold without it.
     
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  7. Scott215

    Scott215 Well-Known Member

    622
    Jun 4, 2022
    2006 215 weekender 5.0 mpi
    5.0 mpi alpha 1 gen 2
    I just use it as a safety precaution just to make sure I don't have any leaks I hope you don't I hope it's something simple
     
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  8. Tacoma290

    Tacoma290 Active Member

    492
    Oct 5, 2006
    Tacoma, WA
    340 Sundancer 2007
    Twin 8.1 V-drives
    @PlayDate :Thanks for the list. I sent the two oil samples in at the same time, but Blackstone received them on two different days; I expect to hear back from them tomorrow and will re-post
    @JHornsby3 : No I did not add any ATF to flush. In hindsight, yes I should have. I already have the correct fresh oil in it now; I will pull the oil cooler to pressure test it, which will loose some oil. I should be able to add ATF to top off.
    @Scott215: For this round, I stuck with exactly what was in the Mercruiser manual. But will likely pick some up for the eventual next round.
     
  9. SKybolt

    SKybolt Well-Known Member SILVER Sponsor

    Nov 11, 2014
    Kent Narrows, MD
    Reel Nauti
    460 EC
    Detroit 6v92TA
    (Low profile's)
    Alison Gears
    Westerbeke
    12.5kw Genset
    I have replaced my share of head gaskets on gas engines, diesels as well, and never have used anything on head gaskets. If the heads were checked properly by a qualified machine shop then you should not need any gasket sealer. If you used a steel gasket then that could be an issue.
     
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  10. JHornsby3

    JHornsby3 Well-Known Member

    Nov 10, 2020
    Sheridan Oregon
    "Steele'y Tutz"
    1992 300 Sundancer
    Twin 4.3L W/Alpha One Gen II
    No I did not add any ATF to flush. In hindsight, yes I should have. I already have the correct fresh oil in it now; I will pull the oil cooler to pressure test it, which will loose some oil. I should be able to add ATF to top off.

    Dont leave ATF in with the oil for service, The high detergents in the ATF isn't good for running. Using it as a flush, and not very long, is all you want to do with it.
     
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  11. Tacoma290

    Tacoma290 Active Member

    492
    Oct 5, 2006
    Tacoma, WA
    340 Sundancer 2007
    Twin 8.1 V-drives
    @PlayDate: Below is the sample for the Port side, which is much better and backs up Blackstone's average value data.
    As a side note, I have never had so few hours in a season, due to battling through this.
    [​IMG]
     
    PlayDate likes this.
  12. PlayDate

    PlayDate Well-Known Member

    Dec 25, 2006
    Washington DC
    1994 370 Express Cruiser
    454 Mercruisers
    I’m headed back to your original post for a moment. You mentioned that a clamp failed and the risers got very hot. Does that mean the clamp was on the raw water side?

    If it was….it would explain the risers getting really hot. The coolant side had to get really hot to fail a head gasket and drop the oil pressure.

    I’m starting to be concerned that you may have a crack from the overheat. To test this you need to get one of these and pressurize your fresh water (coolant) system.

    I know Blackstone is leaning toward seawater but we need to make sure the fresh water side is water tight.


    Stant Cooling System Tester, Metallic https://a.co/d/bCcxOVA
     
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  13. Tacoma290

    Tacoma290 Active Member

    492
    Oct 5, 2006
    Tacoma, WA
    340 Sundancer 2007
    Twin 8.1 V-drives
    @PlayDate : Thanks for looking into this. This is an update from last night. So I pulled the oil cooler to have it pressure tested. Then I looked up. I saw corrosion at the top of the exhaust manifold. The manifold has seen 8 hours of run time. Here is what I saw.
    [​IMG]
    The bolts riser-elbow bolts were not as tight as they should have been on this side (all the other risers still looked perfect). When I tightened the two outside bolts, more water weeped from the joint.
    So then I pulled the elbow. More water weeped as I pulled it. Here is what I saw on the bottom of the elbow:
    [​IMG]
    And the top of the manifold was very wet:
    [​IMG]
    More corrosion on the inside than I would expect on 8 hours. On the right hand side of the picture, I saw moisture at the bottom of the manifold. I wrapped a socket extension with a shop towel, and pulled as much of the moisture as I could. It tasted very salty.
    I pulled the plugs on that side. They look terrible.
    [​IMG]
    It was getting dark and late, so before leaving, I hit the open cylinders with fogging oil. I will head back out to the boat later today.
     
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  14. Tacoma290

    Tacoma290 Active Member

    492
    Oct 5, 2006
    Tacoma, WA
    340 Sundancer 2007
    Twin 8.1 V-drives
    No water came out of any of the cylinders when I pulled the plugs.

    So when I started the engines last week, this engine sounded rough for a few seconds then sounded fine as it heated up.

    So the question is whether this is the cause or a symptom of something else?
    If I see signs of this much water on the outside of the manifold, is it likely that exhaust air is also leaking at this joint, which at idle may not create enough lift to get the raw water all the way up the elbow so it falls back to the manifold? Any other conclusions to come to?

    It seems that taking the oil cooler to an exhaust shop is not a good use of time, since the oil in the cooler was perfect. I am thinking I need to reinstall the oil cooler, pull the rest of the plugs, put the exhaust back together, and turn the engine over asap (treat the event as if I am trying to avoid a hydrolock).
     
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  15. KevinC

    KevinC Well-Known Member

    Feb 25, 2011
    Long Island, NY
    2004 340 Sundancer
    Twin 8.1 V-drives
    Did you replace the elbows when you replaced the manifolds? They may have a crack in one of the welds and leaking back. If the elbows are still off you should be able to test them.

    -Kevin
     
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  16. PlayDate

    PlayDate Well-Known Member

    Dec 25, 2006
    Washington DC
    1994 370 Express Cruiser
    454 Mercruisers
    Well.....you at least know where (at least one area) the sea water is getting into the combustion chambers.

    When you get a chance.....post the starboard engine number. I'll make an assumption that your manifolds are fresh water cooled and the riser is raw water cooled since you have a block off gasket between them.

    What appears to be happening is the riser/elbow is leaking raw water into the manifold. The gasket seems to be containing the coolant but the raw water is leaking around the inverted ring (to minimize reversion) and pooling there. From there it is leaking out of the top of the gasket and overflowing into the manifold.

    What is the story with the riser/elbow? You mentioned in the first thread they got extremely hot. Also I'm still interested in what clamp originally failed.
     
  17. Tacoma290

    Tacoma290 Active Member

    492
    Oct 5, 2006
    Tacoma, WA
    340 Sundancer 2007
    Twin 8.1 V-drives
    Again, thanks for the comments.
    STBD SN = 0W393939
    No coolant at the gasket or the manifold. Raw water only.
    I will check the elbow again. It is stainless and appeared to be in good shape prior to reinstalling the heads. And there were no signs of salt on the outside of the elbow (that is one good part of phantom black paint), like there is on the top of the manifold.
    Below is a diagram of the closed cooling system.

    Let me know what you think of the leak at the elbow manifold gasket; it is possibly leaking exhaust gas as well as water. Exhaust pressure is what lifts the raw water up through the elbow. If there is a leak at that joint (especially at idle), there would be less pressure to lift the raw water. It could be that there is a standing column of water sitting on the turbulator, and when the engine is turned off, the water falls down on the manifold. When the engine is restarted, some water is let into the engine. The water can't compress, so it leaks by the cylinders and into the oil.

    The failed clamp was on the seawater at the outlet of the air actuator (Item 2), before it elbows up to the transmission cooler. (Item 3). The raw water was being dumped into the bilge. Without the raw water, the exhaust got hot very quickly and the coolant got hot as well.
    [​IMG]
     
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  18. scoflaw

    scoflaw Well-Known Member

    Aug 10, 2011
    cape cod mass, cape coral fl
    1999 Powerquest legend 260 sx 502 mag
    2005 Baja 242 islander 496
    502 mpi Bravo 1
    496 mag B1
    Not how that system works. There is only exhaust at the manifold elbow gasket, no water. The water is not lifted by exhaust, it's under pressure from the pump and gets directed from manifold to the elbow. Turbulators purpose is to catch condensation that's created from temperature differences.
     
  19. Tacoma290

    Tacoma290 Active Member

    492
    Oct 5, 2006
    Tacoma, WA
    340 Sundancer 2007
    Twin 8.1 V-drives
    I agree with you, @scofflaw.
    Here is a picture of the same engine as mine, but for an outdrive application. The raw water and exhaust are the same as mine: I believe the raw water is pumped up through the bottom of the exhaust manifold (at the fitting with red threadlock), out the two rubber hoses at the top of the manifold, and into the stainless elbow where it mixes with exhaust.
    [​IMG]
     
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  20. scoflaw

    scoflaw Well-Known Member

    Aug 10, 2011
    cape cod mass, cape coral fl
    1999 Powerquest legend 260 sx 502 mag
    2005 Baja 242 islander 496
    502 mpi Bravo 1
    496 mag B1
    Correct, I own that engine and very familiar with it
     

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