How to Repair a Drowned Outboard

Following the outboard repair tips below, we had it working again the next day, and for the remainder of the three-week program

I was running a sailing and diving trip in the Leeward Islands one winter for the Raleigh, N.C.-based outdoor adventure company, Broadreach (gobroadreach.com). We were anchored off of St. Barth’s while our dive instructor took our six students out in the big RIB and accidentally flipped the boat in the surf (no casualties, save for a few dive weights). How to repair the outboard?

The 40hp Yamaha was submerged for over two hours before we were able to right it.

Following the outboard repair tips below, we had it working again the next day, and for the remainder of the three-week program. So pay attention – the tips work!

Using the Outboard Repair Tips, we had it running the next day! Photo by Maria Karlsson
Using the Outboard Repair Tips, we had it running the next day! Photo by Maria Karlsson

How to Repair Drowned Outboard

  1. First and foremost, ensure you haven’t done any damage to the environment from leaked fuel or oil. If so, take care of that first through appropriate channels. Don’t lose sight of the big picture.
  2. Get the motor out of the drink quickly and rinse it thoroughly with fresh water. Most importantly, do not let it dry. Once the water begins to evaporate, corrosion will set in and can cause permanent damage, especially if the engine was submerged in saltwater.
  3. Remove the spark plugs, fuel lines and carburetor, liberally applying WD-40 as you go to remove the water (“WD” after all, stands for “Water Displacement”).
  4. Spray inside the cylinders, or better still, rinse the chamber with methylated spirits. Again, water is the enemy.
  5. Remove the carburetor, carefully wipe it clean and douse it with WD-40.
  6. Hand-crank the engine while it’s disassembled. This will physically force out whatever water is left in the cylinders (usually lots). Without spark plugs and compression, this is surprisingly easy so don’t snap the pull cord. When it feels sufficiently purged, crank it some more.
  7. Install new spark plugs and reassemble the rest of the engine.
  8. Double the oil mixture in new, clean fuel. Then it’s the moment of truth – if it fires, let it run for at least 20 minutes.
  9. No luck? Disassemble everything. Repeat the water removal process and leave the parts and the engine to dry out in the warm sun for a while. (Do NOT put anything in the oven, as is sometimes suggested).
  10. After a few hours, re-assemble and try to start the engine again.

Get the motor to an outboard repair professional (especially newer four-stroke models) for a more thorough service after a submerging, even if it does come back to life.

Andy Schell
Andy Schell is a professional sailor, writer and the event manager of the ARC Caribbean 1500. You can find him online at 59-north.com.