Flushing and Rinsing: Salt Removal After Every Trip

Salt water is the reason marine engines cost what they do and last as short a time as they do. Every trip leaves the inside of the cooling system full of it, and when the engine cools the water evaporates and the salt does not. It crystallises in the water jackets, packs into the thermostat housing, and starts eating aluminium the moment it dries. The single most effective thing an owner can do for an engine's life is also the cheapest: get the salt out before it sets.

Why flushing matters more here than most places

The gulfs are warm and salty, and a boat on the Yorke Peninsula spends its whole life in water that is doing its best to corrode it. The corrosion does not happen while the engine is running — there is too much water moving. It happens on the trailer, over the following days, as the residue dries. An engine flushed after every trip and an engine flushed never will look the same from the outside for years. Inside, they are different machines.

Flushing an outboard

There are two ways, and it matters which your engine uses.

Muffs over the water intakes. The traditional method: clamp a flushing attachment over the intake grilles on the leg, connect a hose, turn the tap on until water is flowing out around the muffs, and then start the engine. Run it at idle — not above — for five to ten minutes, until the water from the tell-tale runs clear and, on a thermostat-equipped engine, warm. Never run it dry, even for a few seconds: the water pump impeller relies on the water for lubrication and it will strip in moments without it. A universal muff such as the oval motor flusher covers most engines, and there are shaped versions for the smaller legs in our engine flushers range.

The flush port. Most outboards from the last twenty years have a hose fitting on the powerhead or the cowl. On the majority of these the engine is flushed switched off: connect the hose, run the tap for ten minutes, disconnect. The water goes through the block by its own pressure and out the leg. Check the manual, because a few engines want to be run during a port flush and running one that does not is a way to damage the pump. The flush port is convenient, but it does not flush the water pump housing or the lower leg, so a muff flush every few trips is still worth doing.

Either way, tilt the engine down afterwards so the leg drains. An outboard stored tilted up holds water in the passages and, in a frost, cracks.

Flushing a sterndrive or inboard

Sterndrives flush much like an outboard: muffs on the drive, engine at idle, until the temperature comes up and the thermostat opens. On a boat with a raw-water cooled inboard, a flushing tee in the intake hose lets you feed fresh water in without pulling the intake off; on a closed-circuit engine you are only flushing the raw-water side, the heat exchanger and the exhaust, which is exactly the part that needs it. Salt in the heat exchanger tubes is what leads to the overheating problems our diesel owners bring in.

Rinsing everything else

The engine gets the attention, but salt is working on the whole rig. After the flush, hose down the outside of the engine, the trailer, the hull, and everything metal on the boat. The trailer especially: brakes, springs, hubs and lights are all sitting in dried salt within an hour of the ramp, and a trailer that is rinsed lasts several times longer than one that is not. Our guide to trailer bearings explains why the hubs in particular deserve it.

A plain fresh-water hose does most of the work. A salt-removing wash does the rest, because salt bonds to surfaces in a way that water alone lifts slowly; a product designed to dissolve it, applied through a hose-end mixer, gets into the places a hose does not, and is worth using on the engine exterior, the trailer and any stainless. The Salty Captain range is built around exactly this job — a salt-removing wash for the rig, and separate products for the hull, the vinyl and the clears.

Under the cowl

Once a season, or after a rough trip with spray over the transom, take the cowl off and look. Salt crust on the powerhead, white corrosion on the aluminium, green on the copper. Rinse it gently with fresh water — not a pressure washer, which drives water into connectors — let it dry, and then spray the powerhead and the electrical connectors with a corrosion-inhibiting spray. Ten minutes a year, and it is the difference between an engine that looks its age and one that does not. The sprays and protectants are in our cleaning and detailing supplies.

None of this is complicated, and none of it is optional if you want the engine to last. If you would rather it were done properly once a season along with everything else, that is part of the pre-season and post-season work we do through the Kadina workshop. Ring 0412 532 984.