How To Clean The Salt Water Build Up In A Boats Exhaust Manifold

Breathing Easier

Inspecting your gunkhole's exhaust organisation at present might save your engine after. Or your life.

When was the last fourth dimension y'all inspected your gunkhole's frazzle system? I'm guessing never: Most of us take our manifolds, elbows, risers, and mufflers for granted, and in nearly cases our neglect is rewarded by years of problem-gratis service. The exhaust keeps exhaling through the frazzle ports, the carbon-monoxide alarm doesn't go off, the pyrometer needle stays where it ought to be, and the engine runs cool and happy. Everything's copacetic, then why worry?

Here'southward why: If the exhaust organization springs a leak, information technology tin fill your bilge with h2o or, even worse, your motel with lethal carbon monoxide. (Your CO detectors volition warn you of this, merely they don't last forever: Some have lifespans as short as five years. Check yours to ensure they're all the same protecting yous.) Less catastrophic than asphyxiation, a corroded frazzle riser can nevertheless open a path for cooling water to seep dorsum into your exhaust manifold, and perhaps into a combustion bedchamber via an open up frazzle valve. If that happens, the next time you crank the engine, you might get a lesson in hydraulics, as the incompressible water meets the compression-stroking piston. The winner? Your mechanic.

The good news is, exhaust-system failures are easy to forestall, about as easy every bit anything gets on your boat. All you need is a flashlight, the willingness to crawl into the remotest parts of your bilge, and common sense.

It's Hot and It'due south Wet

Most yachts accept moisture exhausts; each engine has its own divide arrangement, so with twin engines and a generator, you take 3 to inspect. Although the specific design and components vary widely (the height of the engine relative to the waterline is the primary determinant), the basics of all wet exhausts are the same: Seawater from the engine'south cooling system is injected into the exhaust plumbing downstream of the exhaust manifold or turbocharger. ("Downstream" ways toward the overboard exhaust port.) The water cools the very hot exhaust gases, so the frazzle lines tin be made of rubber or fiberglass rather than rut-resistant steel, making them easy to maintain and repair. The cooling water muffles the engine racket, too, and an inline muffler knocks down the decibels even more. Eventually, the gas/water mix flows into the sea.

Properly engineered wet exhausts work fine virtually all the time. Since the purpose of this cavalcade isn't to redesign your system, but to maintain it, permit's assume yours is done right. That's not always the case, peculiarly if your boat'southward been repowered, or is a one-off from a custom architect: Some of these guys aren't as scrupulous as they should exist. If y'all have any doubts, telephone call in a qualified surveyor or mechanic to check things out. (Northern Lights has a adept, downloadable intro to frazzle system design. You can go more than info at www.northern-lights.com. It's written for generators, simply the principles work for propulsion engines, besides.)

Starting time your inspection at the exhaust manifold, which might accept either a "riser" (it sort of resembles a sink trap turned upside-down) or a simple exhaust elbow bolted to it. The loop in the riser keeps raw water from backflowing into the manifold or turbo. (Some engines take custom stainless steel exhaust plumbing that does the same affair, insulated rather than water-jacketed.) Risers are usually cast iron, and typically h2o-jacketed to continue their surfaces absurd, or at to the lowest degree not blistering hot; if non jacketed, they're wrapped with insulation. Raw water is introduced into the exhaust at the downstream end of the riser.

Risers are the Achilles' heel of whatsoever moisture frazzle organization: If the h2o jacket corrodes away inside, cooling h2o tin leak into the frazzle far enough upstream and then information technology finds its way into the manifold. How long does information technology take for this to happen? BoatUS data suggests saltwater-cooled risers take a l-percent failure rate after roughly five years, but your life expectancy may vary. Power & Motoryacht'due south engine guru, Capt. Richard Thiel, suggests removing the safe exhaust hose from the riser every yr and checking the innards for signs of rust, h2o seepage, and other nasties. I agree. New risers don't cost much, relative to the potential damage caused past one going bad, so replace them sooner rather than later.

Some Like It Dry out

When an engine is mounted deep in a concentrated hull, east.g., a tugboat or long-range trawler, it takes inventiveness, and oftentimes lots of money, to make a water-cooled exhaust system work without risk of back-flooding. So dry (or dry-stack) frazzle has the advantage here. It doesn't utilise water for cooling, so there's no flooding risk. Hot exhaust is ducted up and abroad from the engine through a simple stack, like that on a semi-truck. The only trouble: arranging heavily insulated pipes and so there's plenty cool airflow around them. Dry out-stack commercial boats I've worked on used conventional rut exchangers; raw water came in via a seacock and went out via a through-hull. Checking the flow meant sticking your head out the pilothouse window and listening for the splashing. Some boats utilise keel coolers, an arrangement of pipes outside a hull's bottom. Hot cooling h2o runs into the keel cooler, through the pipes, where seawater cuts its temperature, and then dorsum to the engine. When I was a kid hanging around the local shipyard, all the line-fishing vessels used keel cooling. Those guys couldn't afford downtime, but when it came to maintenance they were equally cheap as Ebenezer Scrooge. Keel cooling worked peachy for them. If you're spec'ing out a new long-range trawler, give it a expect.

Exist A Pyro-Maniac

Look for signs of water leaks around the cooling-water injection nipple, seeping out from under the hose, etc. If a hose clamp is corroded (the screw normally goes first), supercede information technology with a 316 stainless clench intended for marine service—that means the screw is too 316 stainless. Virtually mechanics apply T-bolt hose clamps on exhaust hoses rather than the typical worm-screw clamps, and you should, also. You get a more thorough fit, at least in my opinion. Every hose should be double-clamped.

Downstream of the water-injection point y'all'll find the pyrometer sending unit that measures exhaust-gas temperature; if you don't take a pyrometer, take 1 installed. It's every bit important every bit your engine-temp estimate. If cooling water is cut off—considering the raw-water impeller packs it in, for example, or a plastic bag is sucked into the intake—the temperature inside the exhaust hose will skyrocket rapidly, faster than your engine temperature. The hoses approved for wet exhausts aren't rated for uncooled frazzle gas: Even a top-quality hose like Trident's Blueish Corra-sil (www.tridentmarine.com) is typically rated for just 350 degrees F. Just exhaust gases can exist twice that hot. If you merely monitor an engine-temp judge, your exhaust system may be damaged long before you find overheating. And never ignore overheating: "Information technology must exist a problem with the gauge," isn't the correct response.

Last thing yous should do earlier yous exit this area: Some boats have an anti-siphon loop in the cooling h2o line, oft between the h2o pump and the heat exchanger, or just alee of the injection point into the exhaust. Why in Neptune's proper name would they do that? Anti-siphon loops are installed when the injection betoken for the cooling water is below, or even near, the gunkhole's waterline. Siphoning can develop if the raw-water pump lets h2o run through information technology, east.g., if the impeller is worn. In the worst case, siphoned water tin fill the waterlift muffler (typically used when the engine is lower than or at the waterline), then fill the frazzle hoses, and finally support into the manifold. Over again, not a good state of affairs for you, but excellent for your mechanic. (And another reason to supplant your raw-water impeller every season.) Unscrew the siphon-break valve on the top of the loop and make clean the salt or other gunk out of it. Instead of a loop, some installations employ a tube that vents overboard; bank check its fastenings at both ends, and make certain the tube is clear.

Plug That Muffler!

Finally, nosotros can motility away from the engine and follow the plumbing toward the frazzle port, usually in the transom. Forth the way, look for leaks where the hose connects to elbows or solid sections of pipe (usually fiberglass); discolored sections, which can indicate overheating; corroded hose clamps; cracks in solid pipe; worn spots in a hose from chafing against hull structure, or where it passes through bulkheads; broken hangers or back up brackets—basically, continue an eye out for anything that doesn't look right.

Some boats accept inline mufflers, similar to the one in your car, merely more oftentimes you'll find a waterlift muffler, substantially a canister of water bolted securely to the hull structure. In that location's a pipe in, and a piping out; exhaust flows into the muffler, filling the canister with water and gas until the pressure is groovy enough to forcefulness some of the mixture upwards the "out" pipe so through the frazzle port. The vertical leave pipe rises above the level of the entry port to an elbow that serves as a secondary riser, preventing seawater from flowing back into the frazzle plumbing. The water in the canister also muffles frazzle dissonance.

All waterlift and most inline mufflers take drain plugs that a mechanic will remove when winterizing the boat. Brand sure the plugs are in identify and deeply tightened; if one backs out, water and frazzle gas will escape into the gunkhole. The water can fill the bilge, and the gas can make full your lungs. Neither i is a proficient thing, merely both are easy to forestall by spending a little quality fourth dimension with your exhaust arrangement.

This commodity originally appeared in the June 2022 event of Power & Motoryacht magazine.

Source: https://www.powerandmotoryacht.com/maintenance/how-to-maintain-the-exhaust-system-on-your-boat

Posted by: kulikowskitheaught.blogspot.com

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