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Another cracked head!

Discussion in 'Ocean Yacht' started by praetorian47, Nov 1, 2019.

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  1. Beau

    Beau Senior Member

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    I'm very surprised the OP doesn't have those strainers on his Ocean. Wonder if a prior owner removed them. Sucking up a plastic bag into the raw water side ain't good. Whoops, just read post #41 - he found them.
  2. PamSails

    PamSails New Member

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    Has anyone put in a sea strainer in the line to the seawater pump? Or perhaps a sea chest to service both engines?
  3. praetorian47

    praetorian47 Senior Member

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    What's a sea chest? I don't think I have that.
  4. Capt Ralph

    Capt Ralph Senior Member

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    Buck makes strainers like in line fuel filters. Called low profile.
    Sea chest usually have a screen or circular strainer built in. An extra strainer outside the chest would not go to waste capturing extra silt.
  5. Capt Ralph

    Capt Ralph Senior Member

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    Easy to answer; If you don't know what a sea chest is, you don't have one.

    One big hole in your ship that supplies green water to everything from one supply point.
    Cocks and maybe strainers attached to all the raw water devices.
    Last edited: Nov 7, 2019
  6. C team

    C team Senior Member

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    I did add strainers after the seacock on my Egg. It also made winterizing much easier.

    Attached Files:

  7. cleanslate

    cleanslate Senior Member

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    Do you still have the scoop strainer and the inboard strainer on, or just the inboard one now ? with a slit clam shell , if you will , thru-hull for the engines?
  8. cleanslate

    cleanslate Senior Member

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    It's easy to get off, I have them to on my Ocean. Two screws at the ends of the screen, remove them. Then the screen slides out aft, its in a groove. You may have to put a light hammer and screw driver to it to get it to slide out. Put the screw driver in one of the holes in the screen at an angle and tap on the screw drive aft to get it to slide out. Clean the screen by sanding down and soaking in some acetone or lacquer thinner to clean out the junk in the screen.
    As said before look up and in the thru- hull and sea cock for junk, clean that out to. Slide the screen back in and if you want lightly paint it , with a brush, not roller with bottom paint. one coat , so not to pug up the holes. that will help keep it clean while in the water.
  9. C team

    C team Senior Member

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    I kept the scoop strainer on when I added the inboard strainers.
  10. Boomer

    Boomer Senior Member

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    After painting the scoop screen,take an Allen wrench and poke the holes open so you get good water flow
  11. Beau

    Beau Senior Member

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    Some recommend a drill sized for the strainer holes placed in an electric drill in right rotation which tends to bring the removed paint material out rather than in...just another option.
  12. praetorian47

    praetorian47 Senior Member

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    We now have both heads off. Saw the crack when we got them into the light. 1 head is good but I'm replacing both.
    We've used a snake camera to check through the strainers and found no issue. One plug on the heat exchanger did have some corrosion so we've got that in for cleaning/repair. the other one was clean.

    At this point, my buddy is trying to find new, non-remanned heads, but I'm doubtful. I have 1 head that I bought a couple years ago, the marina lost it so I had to buy another before they found it. It's a remanned head from Northwest Casting Service. Being a bit gun shy of poor reman jobs, should I use this head or get another from the source I've used since this?

    Any advice is appreciated. I'm actually getting good at changing heads - but I never want to do it again!
  13. Capt J

    Capt J Senior Member

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    Have it checked by a good cylinder head shop that is familiar with D.D. heads. See what they say.
  14. DOCKMASTER

    DOCKMASTER Senior Member

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    Reading through this post makes me feel better on my decision to yank out my 12v92’s and replace them. I had a head problem on the Port engine, ending up sucking a valve, destroying a cylinder, and turbos. Coolant and oil mixed and ending up having to replace all the main and rod bearings, oil coolers, etc due to contamination. The following season we had head issue on stbd engine and was getting over pressurization of coolant side and blowing all the coolant back out the recovery bottle and expansion tank. Never could find the exact source so tore down to parade rest and did a complete overhaul. Ran fine after these issues but given other posts and info on head problems I never really trusted the engines after these episodes so I babied them and usually kept to 70% load max.
    I hope your fix yours and get some longevity from your 8v92’s.
  15. praetorian47

    praetorian47 Senior Member

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    I spoke with a bunch of older 2 stroke DD mechanics that my buddy knew, and a few suggested that I get new castings - I was surprised but they still make them! The previous owner had an issue with one head and replaced all 4. Since everything else has been considered, the prevailing theory is that we got stitched heads. The only way to really tell is to have in analyzed somehow and I'm told that's expensive too, but I'm debating it.

    I can get new ones, depending on cost, or remanned ones that we know have not been stitched.
  16. PacBlue

    PacBlue Senior Member

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    Detroit Diesel 2-stroke engines/parts are manufactured on some level in the US, although the product line is not as full as before. The Military still buys 2-stroke product for their land vehicles.

    https://detroitreman.com/detroit-parts

    Getting re-manned head from them gives you some assurance that they went through a factory QC process.
  17. T.T.

    T.T. Member

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    thank you PacBlue, this is good info!!
  18. praetorian47

    praetorian47 Senior Member

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    Had the heat exchanger tested and just told that it was leaking on the coolant side. They are trying to repair it, but no idea if they can. Does anybody know where I can get one, if they can't?
  19. Capt Ralph

    Capt Ralph Senior Member

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    Please sead a pic or serial number. There were so many HEs on some models.
  20. DOCKMASTER

    DOCKMASTER Senior Member

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    I hope you have better luck finding a H/E for your DD than I did. One of mine had a warped cover plate. We never did find replacements. Even the DD dealer said they had never seen ones like mine. We managed to very gently straighten the cover in a press and use thick gaskets and held our breath and it did not leak.

    Send a picture and info and maybe you will get lucky finding something.