Registered users don't see ads

Managing a hydro-lock risk.

Discussion in 'Ask All Sailors' started by Gunni, Feb 13, 2018. Add this thread to a FAQ

  1. Gunni

    Gunni

    Joined Mar 16, 2010
    4,633 posts, 722 likes
    Beneteau 411 Oceanis
    US Annapolis
    What is the best way to manage a situation where the engine will not start and extended cranking has filled the exhaust system with sea water? I have a water muffler drain but it is located below a bolted down bilge cover. Removing an exhaust hose and lowering it below the thru-hull is one option. What other options do I have.
     


  2. Don S/V ILLusion

    Don S/V ILLusion

    Joined Sep 25, 2008
    4,855 posts, 187 likes
    Alden 50
    US Sarasota, Florida
    Open the anti-siphon valve assuming you have one.
     


    Gunni likes this.
  3. Gunni

    Gunni

    Joined Mar 16, 2010
    4,633 posts, 722 likes
    Beneteau 411 Oceanis
    US Annapolis
    Yes, that makes sense and it appears to be well above the thru-hull. Thanks.
     


  4. JamesG161

    JamesG161

    Joined Feb 14, 2014
    2,136 posts, 419 likes
    Hunter 430
    US Waveland, MS
    Look at the elevation differences between your engine exhaust Riser and the overboard discharge.
    Mine is well designed so the water cannot back up, unless the muffler is restricted.
    A restricted muffler is obvious since it will not burp, and the discharge is adjacent to the helm for easy and quick detection.
    Jim...
     


    Gunni likes this.
  5. Gunni

    Gunni

    Joined Mar 16, 2010
    4,633 posts, 722 likes
    Beneteau 411 Oceanis
    US Annapolis
    Yes, this is the other hydro lock scenario. I think the procedure here would be to observe the discharge thru-hull after a failed start and wait for the water to stop discharging before attempting another cranking session.
     


    JamesG161 likes this.
  6. dziedzicmj

    dziedzicmj

    Joined Aug 13, 2012
    380 posts, 50 likes
    Catalina 270
    CA Ottawa,ON Ottawa
    I think that the risk of creating a hydro-lock by excessive cranking is overrated. I am not saying you cannot create one, but I think that if you need to crank the engine long enough to create a hydro-lock, you should start investigating the issue (why it is not starting) before. If you need to crank the engine extensively for other reasons (you expect it not to start, but you need to turn the engine anyway), you can close the water intake and remove the impeller.
     


    Last edited: Feb 13, 2018
    Gunni likes this.
  7. Gunni

    Gunni

    Joined Mar 16, 2010
    4,633 posts, 722 likes
    Beneteau 411 Oceanis
    US Annapolis
    Having chewed up an impeller because I forgot to open a genset raw water thruhull I can say that running an engine with the thru-hull shut off can create massive problems - like hours of disassembling the raw water circuit to find the pieces of impeller that are now clogging the system.

    Reviewing my installation layout it is pretty clear that unless I have another existing problem, simply cranking my engine excessively is not going to create a hydro lock situation.
     


    JamesG161 likes this.
  8. JamesG161

    JamesG161

    Joined Feb 14, 2014
    2,136 posts, 419 likes
    Hunter 430
    US Waveland, MS
    Me too:redface:. I took less than 30 seconds and burnt rubber smell/smoke.
    I got lucky and was able to "blow back" to clean out system, after that goof. I now have a Tag and Retrieve method of accounting for all seacock positions before/after a sail.
    Check my post#32 for pictures and method.
    https://forums.sailboatowners.com/index.php?threads/shutoff-valves-open-or-closed.175684/page-2
    Jim...
     


  9. Maine Sail

    Maine Sail Moderator

    Joined Feb 6, 1998
    10,487 posts, 387 likes
    Canadian Sailcraft 36T
    US Casco Bay, ME
    Just be sure your wet exhaust hose does not disappear to a very high point, as most will, before dropping to the exhaust outlet.. Closing the seacock and cranking the motor will not immediately destroy an impeller, as the water can not be fully expelled for some time with the intake end closed. To destroy one takes longer than the time it takes you to get down there and open it. Now, if you started with a bone dry pump, you can destroy one pretty quickly but with water already in there it will run for plenty long enough for you to jump in there and open it.

    Best bet is to install a remote start switch in the engine bay, great for oil changes etc., or use a portable one.

    I have seen, heard of or flixed numerous engines hydro-locked over the years from over-cranking. It's usually due to an owner changing fuel filters then getting air trapped and cranking to try and clear air. In over-cranking hydro-locks the engines are rarely ruined, if serviced ASAP, but I have seen two starters burned up because the owner kept trying to crank....

    I've also seen hydro-locks due to failed anti-siphon valves, no anti-siphon valve, a broken wire tie, scoop strainers mounted in the wrong direction, incorrect winterizing & engine flushing flub ups......... In only about half of these events was the engine totaled.
     


  10. Gunni

    Gunni

    Joined Mar 16, 2010
    4,633 posts, 722 likes
    Beneteau 411 Oceanis
    US Annapolis
    I need to check the the elevation of the loop, it was moved a bit during some work last year.
     


  11. walmsleyc

    walmsleyc

    Joined Feb 2, 2006
    338 posts, 10 likes
    Hunter Legend 35
    CN Kingston
    I gave myself a hyrolock this past fall. The primary problem that started off the whole mess was water in the fuel.

    In literally the last motor to the fuel dock to pump out, just before haulout, the engine stopped .... of course, right in the middle of the fairway with rocks of one side and boats on the other. After getting ourselves to a dock, and checking things, I determined that water was my problem. So, I drained the filter, and pumped my primer bulb until only clear fuel came out. After turning over a bunch, it still didn't start, so I assumed I might have got some air into the system, so I started the bleed process. Just as I was finishing the bleeding process, and had finished turning over the engine to bleed the injectors, and was turning over the engine to get it started, when it felt like it was just about to kick over as fire up, it stopped abruptly. That's when I realized that I forgot to close the intake seacock!!! I wasn't 100% sure there was water in the cylinders, but wasn't going to take the chance and the way it thudded to a stop was not normal.

    To clear the water, I closed the intake seacock, then removed the exhaust from the input (bottom) of the water lift, and let it flow into the bilge under the engine. It happens that the layout of my boat make this manageable. I then opened the decompression valves, and then turned over the engine until no more water came out of the exhaust hose (a few cups of water came out during engine turnover). A quick touch of the starter button with the decompression levers closed and the engine turned over normally. Whew! Reconnected the exhaust, and it fired up immediately.

    The process of trying to start with water in the fuel, then air in the fuel, then the bleeding process eventually filled up the muffler!

    I have a speedseal cover, with the Teflon spacers, on my water pump, so I wasn't too worried about wrecking the impeller. Upon winterizing inspection, the impeller was fine.

    Cheers
    Chris
     


  12. Gunni

    Gunni

    Joined Mar 16, 2010
    4,633 posts, 722 likes
    Beneteau 411 Oceanis
    US Annapolis
    Chris, that would suggest that triggering the compression release allowed water that was already in the cylinder(s) (and had stopped your engine) was blown out with no damage to the engine. How tough is it to run a compression test on your engine?
     


  13. walmsleyc

    walmsleyc

    Joined Feb 2, 2006
    338 posts, 10 likes
    Hunter Legend 35
    CN Kingston
    It appeared (by how it started and ran) that there was no damage. After about 5 minutes of running (to get any air or water from the fuel line), I could not tell any difference. All subsequent starts were as per normal. I have good access to the injectors, so testing would not be too hard, but would need compression tester that properly threaded into the injector holes ( I have no idea if there are standard injector threads and what a 3GM30F has). The engine is a '87, so perhaps I should do a compression check to see where it's at. If the engine misbehaves this spring I might think about testing.

    Chris
     


  14. Gunni

    Gunni

    Joined Mar 16, 2010
    4,633 posts, 722 likes
    Beneteau 411 Oceanis
    US Annapolis
    I once had an auto that I bought used, and it ran fine, if a bit underpowered by my estimate. My mechanic ran a compression test and found low compression in one cylinder. When he took off the head you could see that the engine (which I had put 40k miles on) piston in question was not coming to the top of the cylinder. On disassembly he found a perfectly bent connecting rod that had effectively shortened the piston stroke. At some point prior the head gasket had blown and the engine had hydrolocked.
     


  15. Whatfiero1

    Whatfiero1

    Joined Mar 29, 2017
    142 posts, 18 likes
    Hunter 30t
    US littlecreek littlecreek
    A 5 gal wet vac the hose fits perfectly into exhaust outlet removes the water on spring startup I barely open water inlet to give impeller some water to lubricate impeller then run down to cabin and cut on after it starts
     



Leaky Lewmar ports?
Start by replacing lens gaskets in stock now
Turn any toilet into a Raritan for a fraction of the cost
The Raritan LBA matches your existing bowl with the pump/plumbing of a PHII or PHC. save!
Gray ports and parts
The most popular port on boats built from the 70s into the 90s.
Sunbrella lifesling covers
Any color, fits over existing bag to match your existing canvas.