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Soot exhaust leak

Discussion in 'Technical Discussion' started by Dan balmer, Jan 5, 2020.

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  1. Capt J

    Capt J Senior Member

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    If I remember correctly, you have MTU 8v183's. If so, I would not run them on the hard like that with raw water pump disconnected. I think you'd be better off rotating them with the stop switch engaged to move oil around without letting the engines fire.

    As for running them in the water. I'd rather run all of the engines on yachts I manage 30 minutes or more at the dock than 30 seconds. I run them for a good while until coolant temp rises to 140F or so, then run them up in Neutral to 1500 rpms for several minutes, then slowly bring them down and let them idle for 5 minutes after that, bump them in gear a few times. I haven't had any turbo issues, or any negative oil samples after doing this on many yachts for many years, and the exhaust temp gets over 400F and oil temp does get over 180-200F generally on the ones that show it (MANs).
  2. Capt Ralph

    Capt Ralph Senior Member

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    You have to cover your investments. If the shop warrants the new injectors better, it may be worth serious consideration. IMO. A good injector shop that fixes them in hand is getting harder to find these days. I am spoiled to such a shop in Jax that services AND MATCHES all of my and my customers injectors. I get all the performance of new at reduced cost.
    What I said above, new or used, they need to be popped and matched before installation
  3. Beau

    Beau Senior Member

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    I do same same with my Mans at the dock. At 1000 rpm mine will come up to temp which helps eliminant moisture as well.
  4. Fiammetta42

    Fiammetta42 Member

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    Same here I run my MANs as far as I can up to temp + pressures at the dock in the winter regularly.Just to spread the oil , prevent gaskets shrinking , and get heat into them .Yes a also leave them @ 1500 rpm for 15 mins in N . I think It’s nice for the impellers too ...to keep them fully flexible minimise cracking etc .
    At tick over I turn the shafts too ....just a quick flick in gear that’s all .
  5. mapism

    mapism Member

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    Actually, I believe that what you've got in your engine is a bronze raw water pump.
    This means that you could even not bother disconnecting the belt, because there's no rubber impeller to be damaged when spinning dry.

    There's another big BUT, though:
    You surely have at least one rubber hose bit, at some point along the wet section of the exhaust.
    And that rubber can only withstand the exhaust temperature because it's downstream of the raw water re-injection point.
    Missing the raw water, the gas temperature is not cooled down at all, so it wouldn't take long before those rubber sections would melt, or even burn!
    Can't you just feed the strainers with a fresh water hose of decent capacity?
    I would NEVER run the engines completely dry for more than a few seconds.
    Actually, I would never run them dry, period.
  6. Beau

    Beau Senior Member

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    My thoughts completely. Close off the air passages as discussed and wait for the spring. Then take it for a nice long cruise with fresh oil. Change the oil after 15-20 hours if you think you have junk in it. I think your inside for the winter, yes? That smoke inside the shed should go over well....
    Last edited: Feb 3, 2020
  7. mapism

    mapism Member

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    Agreed, but depending on the installation that might be a bit tricky.
    If the stop solenoid is engaged by turning the key CCV, you can't run the starter to crank the engines while keeping the stop switch engaged.
  8. Dan balmer

    Dan balmer Member

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    Thanks everyone for the input on turning over the engine when on the hard. I realize that this is rather risky without cooling water for the blue silicone rubber connector down stream of the mixing can Just going to leave dehumidifier in engine space and block air entry for 6 months
  9. Oscarvan

    Oscarvan Senior Member

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    You can also put some damp rid in strategic locations. Maybe fabricate something using mesh rolled up in a sausage. Just thinking out loud here.
  10. Beau

    Beau Senior Member

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    Make sure your shrink wrap is covering your air vents, too. So here in the NE for me, the last time I run the engines at the dock is early December, the first time the next season I run them is the end of March or beginning of April depending on the forecast. You can do this while you're shrink wrapped, just be cautious of fumes. The water temp here today is 42 degrees.

    Are you storing down in FL or up here?

    Where is the scavenged water going from your humidifier - the bilge?
    Last edited: Feb 5, 2020
  11. mapism

    mapism Member

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    Good idea.
    That covers 95% of possible problems, and you might wish to consider another couple of tricks for the remaining 5%:

    1) shrink wrap also the external exhaust outputs, which are the only points left for moisture to go inside the cylinders.
    I wouldn't even bother putting a bag around the air filters, with a dehumidifier inside the e/r.

    2) every month or so, you could spin the engine manually by 190 degrees or so.
    This way, any open valve will close, and you will distribute the loaded springs through all the valves during those 6 months, instead of leaving just a few of them constantly loaded.
    It only takes a minute, with a long enough ratchet handle and a 32mm hex socket wrench.
    Btw, this also gives you a rough feeling of how smoothly the engine turns.
    Just remember to spin the crankshaft clockwise.
  12. Dan balmer

    Dan balmer Member

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    I store here in Florida and will route the humidifier water out the crash pump valve at the main intake thru hull
  13. Beau

    Beau Senior Member

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    Sorry. All my comments were based on a NE storage. I know nothing about properly storing in the south.