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Another cracked head!

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

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  1. praetorian47

    praetorian47 Senior Member

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    I want to drain and flush until clean but the PO tried that and I don't think did a good job. I'm told if I don't drain from the right places, crud won't flush out. Trying to learn the best way to do it.

    The crack allows air to enter the cooling system on these. I suppose it could go into the oil, but it's not and I'm told this is common on DD 92s. Just the way it goes, I guess.

    Still cheaper than some other things. My buddy has to do a service on his IPS drives and he will pay the marina almost as much as a head job will cost me (doing it with my own mechanic)!
  2. Beau

    Beau Senior Member

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  3. boatpoor

    boatpoor Member

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    185-190 is too hot for a Detroit. You need to look at the cooling system and thermostats in particular. These engines won't survive at that temperature. I try to keep all our Detroits under 180. Cracks between the valves will put compressed fuel and air into the coolant not the oil pan so you should be okay there. Ralph is correct is his assessment of Detroit heads but if you keep them cool they will outlast the cylinders.
  4. praetorian47

    praetorian47 Senior Member

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    Ok then, this is a good start.
    I’ll flush the coolant and have the heat exchange looked at.
    I’ll also replace the wires and senders. The bridge gauges are new(ish).
    Would it be worth adding more senders for temp at different spots?
  5. boatpoor

    boatpoor Member

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    I don't think gauges and sending units are the problem if you're seeing temps above 180. You need to look at the cooling system.
  6. praetorian47

    praetorian47 Senior Member

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    I'm seeing above 180 on the bridge gauges, but haven't seen above 165 on the murphy gauage. Now I can't be certain, because I slow down before running down to check the murphy gauge. My wife doesn't like to drive. It's possible it was up higher and dropped before I can get down.

    What should running temps be? My DD truck guy says they'll run at 200 all day, but everybody here seems to think otherwise (and a series of cracked heads would support the lower number!)

    What thermostats should I be using? Could the wrong ones cause this?

    I think the PO had heat problems and that's why he did the flush. He told me he thought there was a build up in the coolant system, possibly from an incorrect coolant/water mix, or just from age. He used some chemical, ran the boat and hour or so, flushed with water and ran another hour or so, then returned to a coolant mix. That was shortly before I bought the boat and started to find crud in the overflow.

    How should I flush the engines? Preferably a way I can do it while out of the water. I've got a few spare pumps of various sizes that I could use to circulate.

    What else should I look at in the cooling system? The heat exchangers have been looked at and I'm told they're fine.

    Thanks for all the help and support so far. This is frustrating, more so because I can't figure out what's wrong!
  7. Beau

    Beau Senior Member

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    Are you out of the water? I'm a Man guy, but first thought for me is that someone has to get down in ER with an infrared gun if your gauges are actually reading differently, ( probably not) and that will take 2 people

    The circulating water system definitely needs to be flushed until it runs clean water.

    I would also take careful notice of the advice you're given on this site, (running temps). Many of these folks are experts in the marine industry.
  8. praetorian47

    praetorian47 Senior Member

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    This may sound silly, so forgive my ignorance. I don't think I have raw water strainers. I see the inlet for raw water but there isn't a strainer there that I can see. Is it possible I don't have one? Maybe it's there and I'm an idiot and don't see it?
  9. praetorian47

    praetorian47 Senior Member

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    Beau,
    I'm out of the water now. My gauges do run differently, we've verified that at warm up at the dock, what I'm not sure is how big the difference is at load.
    I am taking everything said here and looking at it, everything!
  10. praetorian47

    praetorian47 Senior Member

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  11. C team

    C team Senior Member

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    I know a few Jersey built boats did not use raw water strainers in the engine room for a number of years. Egg Harbors and Posts used a strainer under the hull before going through the seacock.
  12. praetorian47

    praetorian47 Senior Member

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    Since it's out of the water, that should be easy to check :) I'll try to get there tomorrow!
  13. Beau

    Beau Senior Member

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    Exactly
  14. Beau

    Beau Senior Member

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    If they do read differently, more reason for the infrared to find out which ones are closest to being correct. Additionally, do the gauges run off different sensors? If so switch them in the Spring and see what you get.
  15. praetorian47

    praetorian47 Senior Member

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    I've always suspected a wiring issue with the bridge displays. the mechanical gauge was tested accurate (at the dock).
    The bridge gauge would go screwy when I turned on my engine synchronizer up until this year (I ran new wires to that). IT would go up 20 degrees as soon as I engaged it, drop as soon as I turned it off - only when the engine was running though.
  16. boatpoor

    boatpoor Member

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    Going back to your post#26 , if you're coolant mixture is off, this can create much more serious problems in the 92's with the wet liners. They won't survive in a system without the mixture being where it should be. I would flush them with Ryd Lime and screen the return to tank so you can see what your getting out of the system. Keep flushing until the return runs clear, rinse with fresh water and replenish the coolant with power cool.
  17. boatpoor

    boatpoor Member

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    Oh, and I use 170 degree thermostats in mine.
  18. praetorian47

    praetorian47 Senior Member

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    Thanks. I’m planning on doing he ridlyme flushing for sure.

    I’m going try to get there today or later this week and check the strainer. Not sure what I’m looking for but will look under the boat and hopefully it will make sense.
  19. alvareza

    alvareza Member

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    Picture of the external strainer for the engine on my Ocean

    upload_2019-11-6_10-1-38.png
  20. praetorian47

    praetorian47 Senior Member

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    I'm pretty sure I don't have one of those.

    Maybe I do t have one at all?

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