What kind of madman would intentionally pitch a perfectly good outboard engine over the side of his boat? Yep, that would be me. But I haven’t lost my mind, mechanical frustration hasn’t made me go insane, and crazy thoughts haven’t caused me to strand myself at sea. In fact, I had a completely reasonable motive for giving my trusty old four-horse Mariner the heave-ho into a briny bath: to help fellow boaters who find themselves in a similar situation, by accident.
If your outboard gets submerged in salt water—whether it's because it jumped off the transom, your boat sank, or you got a bad case of butter-fingers while walking down the dock—you’ll need to know how to get it up and running again, while also protecting it from an explosion of corrosion. The process is called “pickling." We’re going to walk you through the experience first-hand with my little Mariner, both here and in our companion how-to pickling video, so if you ever need to pickle your own outboard, you’ll know what to do.
Before giving my hapless horses the heave-ho, I’ve set up an emergency outboard operating center back at the house. No, most of us won’t have the clairvoyance to do this before our engines get dunked, but we’ll still need to start this process properly prepared—even if it means letting the engine soak longer than otherwise necessary. Why? Because the single most important thing you need to remember about pickling an outboard is to begin this process immediately after removal from the water. In fact, it’s better to leave an outboard submerged for hours at a time and then pickle it immediately, than it is to pull it out of the water immediately and leave it exposed to the air for several hours.
The reason why is simple: corrosion takes place very slowly as long as the engine is completely submerged, but as soon as the air hits it, that nasty orange crud we all love to hate is going to start blossoming all over the place. If any forms in a cylinder—and if the submersion was complete it almost certainly will—even the tiniest amount can spell doom for the powerhead. So if your engine is sitting underwater, don’t be too quick to yank it right back out. First, make sure you have a way to transport it to a suitable place for pickling in a matter of minutes, not hours.
What should you do if you need to drive for an hour or more, to get your engine home? If at all possible, keep the motor submerged as you transport it. Depending on its size and weight you may be able to keep it in a large cooler filled with water, or some other form of make-shift tank. Another alternative is to gather all of your pickling tools and find a near-by boatyard, a friend’s house, or even a parking lot, where you can get the job done post-haste.
To prepare for the pickling, there are a few items you’ll need to gather: a freshwater hose; the tools necessary to break down the engine’s major components; several buckets; a gallon of diesel fuel; fresh gasoline (plus an oil filter and oil, if it’s a four-stroke), and a turkey baster or squeeze-bulb. You’ll also need a sawhorse to mount the motor on, if it isn’t still secured to the boat.
Start the process by showering the engine with fresh water. Don’t worry about getting the components saturated—it’s too late for that—just remember that a whole lot of freshwater in and on the engine is far better than a little bit of saltwater. Once it’s thoroughly rinsed down, remove the starter and alternator. Submerge them in a bucket of freshwater and blast them off with the hose, until you’re positive no salt remains. Then encourage them to dry as quickly as possible, as conditions dictate. If you’re at your house or a friend’s, place them in the oven, set it to the lowest temperature possible, and let ‘em bake with the oven’s door open a crack.
Now, you need to get the water out of the rest of the engine. Remove the breather and the spark plug(s), and tilt the motor every which way you can to allow as much water as possible to escape. If your outboard is a four-stroke, this is also the time to drain off the oil and remove the oil filter.
The Big Flush
Now that you’ve washed away all the salt water and drained the engine of all fluids possible, you need to flush it out with diesel fuel. The diesel will displace any remaining water, and (hopefully) carry it all away. Before you begin the flush, make sure to position the engine over a bucket or tub, with a tarp underneath—this could get messy.
Use the turkey baster to blast the diesel into the air intake, until it flows out of the spark plug holes. Use it to flush the crankcase, diesel-wash the carb, and otherwise saturate every crack and crevice inside the powerhead. Also blast it in the opposite direction, via the plug holes. Then replace the lowest spark plug on the powerhead and blast in more diesel, until it flows out of the spark plug hole above it. If your engine has more cylinders and more spark plugs, continue the process until they’re all back in and the engine is completely flooded with diesel.
Once the engine is uber-filled, manually crank it over several times to distribute the diesel evenly throughout the cylinders. Then pull the plugs again, and let the diesel drain down. Replace the oil plug, put on a new filter, and then re-fill the engine oil.
At this point, you can take a breath and slow down. You’ve done what’s necessary to halt the corrosion, and the rest of the pickling process is a bit less time-sensitive. But you’re not quite out of the woods yet.
Next, you’re going to have to flush out all of the internal fuel lines. They may be just fine, but if a single drop of water got into them it’ll lead to trouble. So disconnect them at both ends, flush them out into one of your buckets, and replace any in-line filters. If your engine has an internal fuel tank, drain and refill that, as well.
Now it’s time to reinstall all the parts you removed earlier, except for the spark plugs. If your engine has an electric starting system, go ahead and hook it up to a battery. Then turn the engine quickly a few times, to force any remaining diesel out of the cylinders.
The moment of truth has arrived—put the plugs back in, push the wires onto their ends, hook up a cooling water supply, and cross your fingers. If all went well, the engine should fire right up. Let it run for a good 15 or 20 minutes, so any water that remains hidden in or around the engine gets heated off.
After the engine’s cooled, you’re ready to take the final step: get a good corrosion inhibitor, like CorrosionX or Boeshield T-9, and spritz down every exposed surface, wire, wire connections, and metal part. And after you’ve run the engine for five or 10 hours, give it an extra oil change.
With the process completed on my Mariner, I waited a week to see if any internal corrosion would take hold, then cranked it over. Thankfully, it started and is still running strong today. If your outboard ever takes an inadvertent saltwater bath, follow this pickling process and you should be able to keep your engine’s integrity intact—and hopefully, that’ll help you keep your sanity intact, as well.
If you'd like to see the process I went through with my Mariner, watch the video on Boats.com: How to Salvage (Pickle) an Outboard.
And if you've dropped a four stroke overboard, read How to Pickle a Four Stroke Outboard.