WATER IN THE ENGINE: CLEARING A SWAMPED SKI

The Technique

1. Understand how the water gets in, because that tells you how much of it you are chasing. On a personal watercraft the engine sits in a hull that is designed to keep water out, so a swamping is almost always one of four things: the ski rolled or was held under long enough for the intake to draw water instead of air, the hull swamped and the water level inside rose above the engine, water pushed back up the exhaust while the ski sat stalled and nose down, or a seal, hose or clamp let go and the bilge filled while you were riding. The moment the engine stops and you suspect any of those, the rule is exactly the same as it is for every other engine in this series: do not press the start button. Water does not compress, and a starter motor turning a cylinder full of water bends the rod. One optimistic crank at the beach turns a plug change into an engine. Take the lanyard off so nobody else does it either.
2. Right the ski the correct way and get it in. Almost every hull carries a sticker showing the direction to roll it when it is upside down, and it exists because rolling it the wrong way pushes more water down the exhaust and into the engine. Follow the arrow. If there is no arrow and no manual to hand, roll it so the exhaust outlet ends up rising rather than dropping. Once it is upright, do not attempt to run it home. Get a tow, and tow it slowly and from the bow eye, because dragging a swamped ski at speed forces more water in through the pump and the exhaust. If a trailer or a beach is close, that is better than a long tow. Keep the nose high while you move it, since water inside the hull runs to the lowest point and you want it away from the engine and the electrical box.
3. Drain the hull before you touch the engine. Get the ski onto the trailer or well up the sand with the bow raised, pull the transom drain plugs, and let it run out. Give it time, because a swamped hull holds far more water than it looks like it does and it drains slowly through small plugs. Open the seat or the hood, look at the bilge, and get the rest out with a hand pump, a sponge, a bailer or a rag. Check the bilge hoses and the pickup for the bilge system, since a blocked bilge pickup is often why the hull filled in the first place. While the hull is open, look for the obvious cause: a hose off, a clamp loose, a split bellows, a failed seal at the driveshaft, a cracked exhaust rubber. There is no point clearing the engine if the hull is going to fill again on the next run.
4. Pull the spark plugs and clear the cylinders. Wipe the top of the engine so nothing washes into the bore, pull the leads or the coil sticks off, and wind the plugs out. Before you crank, kill the fuel supply by pulling the fuel pump fuse or relay, because otherwise the pump primes the moment the lanyard goes on and the injectors squirt petrol into open cylinders. Earth the plugs or the leads against bare metal, or unplug the coils. Then lay a rag loosely over the plug holes, fit the lanyard, and hit the start button in short bursts of two or three seconds with a pause between each one. Water will come out of those holes hard, so keep your face clear, keep everyone else clear, and expect it to spray across the engine bay. Between bursts, put a finger loosely over one plug hole and feel what is coming out. Wet slugs become mist, mist becomes clean dry air, and when all you feel is air, several bursts in a row, that cylinder is clear. Do each one. On a two-stroke ski, a small squirt of two-stroke oil down each plug hole once it is dry restores the film of lubrication the water stripped off the bore.
5. Clear the exhaust and the intake. Water sitting in the waterbox and the exhaust hoses will come back up into the engine the moment you shut down at the wrong angle, so with the plugs still out and the bow raised, crank it again and let the engine push what it can out through the exhaust, and if the waterbox has a drain, use it. Look through the intake grate at the pump for weed, rope, sand and impact damage, because a hold-down or a roll in shallow water often puts something through the intake, and a partly blocked pump gives you no cooling flow when you do restart. Check the cooling intake lines and the exhaust rubbers and clamps while you are in there. Make sure the air intake and the flame arrestor are not soaked, and dry them properly, since a wet intake will just carry water straight back down the throat when it fires.
6. Go through the fuel, the air and the electrics before you try to start it. Check for water in the fuel by draining a sample from the water separator if the ski has one, or from the filter, and look for the layer sitting under the petrol. Open the electrical box, and this is the part people rush. Dry every connector you can reach, dry the fuse block, the relays and the battery terminals, and use a light coating of dielectric grease on anything you reconnect. Wet electrics are the reason a ski that cleared perfectly still refuses to run, and they are also the reason it runs today and dies in three weeks. Check the battery is secure and its terminals are clean, since a swamped hull often floats the battery box loose.
7. Fit dry plugs, restore the fuel supply, reconnect the coils, and start it. Never run the engine dry on land for more than a short moment without water supplied to the cooling system, because the exhaust rubbers and the impeller wear ring do not survive it. Either launch it or connect a hose to the flush fitting, and follow the order that protects the engine: start the engine first, then turn the water on, and turn the water off before you shut the engine down. Reversing that order lets water flow back down the exhaust into the cylinders and puts you straight back where you started. Expect it to run rough for the first minute as it clears the last of the moisture, then get it to full operating temperature and hold it there for a decent stretch, because heat is what drives residual moisture out of the crankcase and away from the bearings. On a four-stroke ski, check the oil on the dipstick before and after. Milky, creamy or grey oil means water is in the sump, that oil must be changed before the ski does any real work, and it is worth changing again shortly after because water hides in the cases. On a supercharged or intercooled ski, water can sit in the intercooler and the charge pipes, so drain and dry those as well.
8. If it happened in salt water, the job is only half done. Salt does not stop working when the water dries. It keeps drawing moisture, keeps corroding aluminium and steel, and eats electrical connections from the inside long after everything looks fine. Flush the engine cooling system through the flush fitting with fresh water, using the same start-engine-then-water-on, water-off-then-engine-off order. Then flush what the engine flush does not reach: rinse the entire engine bay, the bilge, the hull sides, the exhaust, the pump and the driveline with fresh water, and get it out again through the drain plugs. Rinse and dry every electrical connector you opened. Once it is dry, treat the bay with a corrosion inhibitor spray, avoiding the belts and the electrical contact faces themselves. If the ski sat submerged in salt for any length of time, plan on a proper strip and inspection rather than a rinse, because salt will already be at the bearings and inside the connectors.
9. Freestyle skis live with this deliberately, and that changes the setup rather than the procedure. A freestyle ski is submerged on purpose, many times a session, so riders build for it: a sealed engine bay and hood seals so the bay does not fill on every submarine, the intake and breathers relocated as high as possible so they are the last thing under, a check valve or a raised loop in the exhaust so water cannot run back down the pipe when the engine stops, the electrical box sealed and the connectors greased, foam in the hull for buoyancy, and a bilge system that actually keeps up. The genuine danger moment for a freestyle ski is not the submersion, it is the stall while submerged, because a running engine keeps pushing water out and a stopped one lets water in. That is why freestyle riders make a habit of getting the ski upright and the nose up immediately on a stall, pulling the plugs on the bank rather than trying to restart, and draining the hull between sets rather than at the end of the day. Whatever the discipline, an engine that has swallowed water deserves a proper inspection once you are home. Check the oil again after a few hours of running, check the bearings and the driveshaft seal, check the exhaust hoses and clamps, and treat a persistent rough idle or a new noise as a reason to stop rather than a quirk to live with.

Common Mistakes

Pressing the start button once to see whether it is alright. Fix: lanyard off, plugs out, cylinders cleared, then and only then does the starter get used for running.

• Rolling an upside-down ski whichever way is easiest. Fix: follow the direction marked on the hull, because the wrong direction feeds the exhaust straight into the engine.
• Running the engine on the trailer with no water to the cooling system. Fix: hose on the flush fitting, engine started first, water on second, water off before shutdown.
• Clearing the cylinders but leaving the electrical box wet. Fix: open it, dry every connector, grease them, and expect trouble weeks later if you skip it.
• Rinsing the outside of a salt-swamped ski and calling it flushed. Fix: flush the engine, then rinse the bay, bilge, pump and connectors, then drain and dry.
• Towing a swamped ski at speed. Fix: slow, from the bow eye, nose high, shortest distance to a beach or a trailer.

The Drill

On the trailer at home, with the ski dry, practise the full plug pull. Find out how you get the seat or hood off single-handed, whether your plug spanner clears the intake, where the fuel pump fuse actually is, and how long the whole sequence takes. Then audit the on-water kit you can realistically carry or keep in the tow vehicle: plug spanner, spare plugs in a sealed tube, screwdriver and nut driver for hose clamps, spare clamps, a hand bilge pump or bailer, rags, cable ties, dielectric grease, a tow rope, and the drain plugs you will otherwise lose in the sand. Practise the salt flush order out loud until start-water-water-stop is automatic.

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