water/steam in exhaust Cummins 4bt

Discussion in 'Diesel Engines' started by Northeaster, Jul 23, 2017.

  1. Northeaster
    Joined: Sep 2011
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    Location: Eastern Canada

    Northeaster Senior Member

    hi folks,

    unfortunately, noticed steam in the exhaust and low coolant (coolant reservoir seemed full enough before first run of season, but engine became starved of coolant when running - started to overheat -so shut down and used outboard to return - took 6 liters of water to bring level back up - ran again and seemed strong but noticed steam.
    I assumed a head gasket blown or cracked head as I did overheat a couple times last year, before adding a larger reservoir and thought I had things beat.
    took head off and at first we though we seen small cracks at thinnest point between valves on two cylinders, but after cleaning off a bit it looks perhaps like previous repairs / pins/ plugs??? as metal looks different in round areas a bit bigger than the head of a pencil, one at thinnest point between valves and another couple between injectors and valves (where they are known to crack I believe)

    I will likely take head to a shop to have checked but after removing the water cooled exhaust manifold from the head, I noticed that the exhaust ports of the head look sooty and dry, whereas the exhaust chamber in the water cooled manifold is definitely wet and follows through to the turbo/ exhaust exit...
    so, can I suspect perhaps the gasket on the manifold, or a cracked manifold??\
    is there any known water/ coolant entrance area on this engine (similar to the Cummins 6BT/5.9) downstream of the head?
    heres a couple of pics - can anyone confirm ifs these are previous pin/ plug repairs visible on the head?
     

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  2. Northeaster
    Joined: Sep 2011
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    Location: Eastern Canada

    Northeaster Senior Member

    A few more pics
    Just took the water inlet of manifold and the gasket betweenit and the manifold was in bad shape and broke apart as I was removing it. Looks to my untrained eye to be a couple of spots/stains where coolant may have been passing between the coolant passages and the exhaust chamber.
    An
    If any experienced hands could have a good look at the pics and weigh in, I would really appreciate it!
    Note. No water in oil.
     

    Attached Files:

  3. Mr Efficiency
    Joined: Oct 2010
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    Location: Australia

    Mr Efficiency Senior Member

    You seem to have found the answer yourself. Does the exhaust passage look different where the gasket appeared broken ?
     
  4. Northeaster
    Joined: Sep 2011
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    Location: Eastern Canada

    Northeaster Senior Member

    thanks for your help gain!
    in the set of pics immediately above, the 1st pic is the end of the exhaust passage, where the inlet part (last 2 pics) bolts on and just plugs the center exhaust channel, as the coolant is injected in outside chambers. From the end of exhaust passage all the way through past the 4 exhaust inlet ports there was some actual water/coolant (which is mostly dried up now a couple hours after taking it apart) but no real noticable differences. as mentioned above, there did not seem to be any water in the exhaust ports of the head, but could that possibly be due to the high temp of the gases sort of drying the ports out a bit......

    i don't claim to have solved it and would love further input from you and others if this old water injection gasket looks like the likely culprit.....
    Still very curious as to the shiny round areas in the head near the injectors and narrow area between vales on a couple of the cylinder.... are these previously repaired areas via welding or pinning with tapered pins, peening and then machining off?
    here is a pic of the water injection part from farther back and one zoomed right in one one area that looks like water/ coolant may have passed by the old gasket, to my untrained eye..
     

    Attached Files:

  5. gonzo
    Joined: Aug 2002
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    Location: Milwaukee, WI

    gonzo Senior Member

    That seems to be the problem. The surfaces will need to be machined.
     
  6. Northeaster
    Joined: Sep 2011
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    Location: Eastern Canada

    Northeaster Senior Member


    You mean professionally machined and not just cleaned with Emery cloth on a straight file? That's what an engine shop said to use to clean up head for gasket.
    Fyi. Engine shop said head looked good and areas in pics were previously welded repairs.
     
  7. gonzo
    Joined: Aug 2002
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    Location: Milwaukee, WI

    gonzo Senior Member

    I have used a belt sander in the field to machine flat a surface. If you are careful, it gives a good result. You can always finish truing it with a file.
     
  8. Northeaster
    Joined: Sep 2011
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    Location: Eastern Canada

    Northeaster Senior Member

    Have the head back on, and the water cooled manifold and turbo - need to find time to get the fuel injection lines back on and a couple of hours for the cooling, plumbing before I can finally see if it all works.
     
  9. Northeaster
    Joined: Sep 2011
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    Location: Eastern Canada

    Northeaster Senior Member

    quick update - all back together and it seems to be working fine. «ran it for about 45 min today - no overheating, no steam in exhaust.
    it looks like the water in exhaust was coming from the old gasket on the water cooled exhaust manifold.
    thanks for the help.
     
    gonzo likes this.
  10. Mr Efficiency
    Joined: Oct 2010
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    Location: Australia

    Mr Efficiency Senior Member

    Good job !
     

  11. Northeaster
    Joined: Sep 2011
    Posts: 256
    Likes: 8, Points: 18, Legacy Rep: 45
    Location: Eastern Canada

    Northeaster Senior Member

    update - unfortunately, after running the boat a few more times, still using water as coolant, the problem reappeared intermittently - never any visible steam out the exhaust, so the new gaskets may have helped some.. but there was still some water/coolant getting in the exhaust.

    well, I finally got around to pressure testing the coolant side (should have done this long ago...lessons learned..).
    As suspected, it would not hold pressure and you could hear air in the exhaust (listening at the turbo). After eliminating the block coolant passages, testing only between the water cooed exhaust manifold and the water cooled turbo, it still would not hold pressure and could hear air through the turbo.
    Finally, took off the exhaust manifold and then you could hear air in through the exhaust ports of the manifold. Then knew about where the leak was and once i blocked off the turbo and filled the exhaust chambers of manifold with water, i could clearly see where the crack was in the manifold - behind one of the frost plugs in the manifold . I knocked out the frost plug to get a better look and confirmed crack with a dye penetrant - you can see red areas in pic...
    wish i would have done this before pulling the head and spending time and money on gaskets,etc but at least know i know what i need.
    The engine performs well so i don't mind spending about $400 on a new manifold- there are chinese aftermarket ones on ebay for that much but also some claiming to be genuine cummins oem for only a bit more.
    if there was better clearance and visibility to the crack i would try mig or tig with silicon bronze or brazing - but i think i would have to cut out an "access" hole to get at it to clean /grind and then repair that as well once the crack was repaired. It may hold but i don't want it to fail next summer or soon after and then still need a new part...so i will likely get a new one.
     

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