What do you do when an onboard pump fails? Here are the answers.
By Vince Daniello
Pumps of all shapes and sizes keep our boats afloat, serve the engines that propel them and provide creature comforts like air conditioning and fresh water. So, when a pump doesn't work, life aboard can turn unpleasant. Here's how to keep the water and your shipboard fun flowing.
ENGINE AND GENSET PUMPS
At the very least, carry a spare raw water pump impeller and cover gasket. But, according to Dick Murray, president of Murray Marine Services in West Palm Beach, Florida, "By the time a new impeller is needed, a pump is often so worn that an impeller isn't the only part you'll need." Considering the importance of propulsion, Murray recommends a complete spare pump. While that sounds like an intimidating emergency repair, from his experience servicing boats of all shapes and sizes since 1972, Murray says it is often easier to change an entire pump than just an impeller, particularly once the pump has failed and gotten hot. Carry a spare belt,too, which should be tightened so it deflects about a half-inch and retightened after a day of running.
For trouble-free operation, check sea strainers before each trip, change the impeller and gasket yearly and replace the pump when water begins dripping from the impeller shaft, a sure sign that bearings and seals are failing. Never lubricate belts, which rely on friction to work.
Engine circulating pumps, which pump antifreeze through the engine and heat exchanger, rarely fail. The best advice is to check engine and generator operating temperatures under heavy load and have the cooling system serviced at the first sign of overheating.
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TIGHTEN YOUR BELT. Use two wrenches and a stout screwdriver to tighten loose pump belts and to retighten new belts after a day's run. |
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KEEPING COUNT. Bilge pump monitors let you know if a pump is running more often than usual, indicating a possible leak. |
BILGE PUMPS
If there is no debris in the bilge, you should get five years or more out of a bilge pump. But tie-wraps, fishing line, carpet pieces, screws and washers can all work their way into the impeller and stop the pump. Often just clearing the impeller will solve the problem, but look for discoloration on the plastic that indicates the pump has gotten hot and should be replaced.
Wiring is the most common bilge pump problem. Use heat-shrink butt splices and secure electrical connections high above the water. Inexpensive float switches also cause problems. Slightly more expensive switches with heavier wires are more reliable. Bilge pumps and switches are sealed at the factory with no serviceable parts, so carry spares of both.
AIR CONDITIONER PUMPS
On many boats air conditioning circulating pumps run almost continuously. This encourages barnacle growth inside the sea strainer and hoses, reducing water flow to the point where air conditioners won't function on hot days or as seawater temperatures climb. Be careful clearing barnacles, since the chips will catch in plastic pump impellers and break off blades. If barnacles are a problem, put a few chlorine tablets the ones used in swimming pools in the sea strainer every four to six weeks. (Only in air conditioners, as chlorine will harm rubber parts in other ship systems.)
Plastic circulating pump heads will also be damaged if run dry, distorting the impeller and entire pump head. Also, the submersible versions of these pumps, those coated entirely in epoxy, are water-cooled. Over time, silt clogs the passageways inside the pump that cool the motor, shortening its life. Since both pump heads and motors are at risk, the most reliable solution is to carry a complete spare pump.
Bronze pumps on larger air conditioning systems can run dry, and bronze impellers won't break from barnacle chips, but over time the metal actually erodes from seawater flow. The first sign of a problem is generally a shaft seal leak, which shows up as water dripping between the bronze pump head and the motor. Motor shafts wear, too, so once again, the only quick, reliable fix is to replace the entire pump.
Constant seawater flow erodes the insides of plumbing fittings, as well, causing sudden leaks or plumbing failures that can result in bigger problems than loss of air conditioning. Murray sees this often with household brass fittings purchased at home stores, which often contain higher percentages of copper in their alloy, making them softer.
Air conditioning seawater strainers are also particularly prone to corrosion, so check them carefully and carry extra stainless-steel strainer baskets. And since air conditioners are often left running with no one aboard, double up all hose clamps, not just those below the waterline, and replace any questionable hoses.
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QUICK CHANGE. Four screws to remove the pressure switch, three more to remove the pump head and two hose connections make changing diaphragm pump heads one of the easiest repairs afloat. |
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LOOK, NO TOOLS. Cartridge pumps are designed to come apart without tools, making them quicker and easier to change and also a great choice for boats that tend to collect debris in the bilge pump impellers. |
PRESSURE WATER PUMPS
Diaphragm pumps are common for pressure water systems, in part because they can tolerate being run without water for a while even an hour or two. As long as the motors are kept dry, they seldom fail, so there is little need for a complete spare pump. The internal workings of diaphragm pumps do wear out, though, and rebuilding diaphragm pumps can be tricky. All it takes is three screws and a couple of push-on electrical connectors to change the whole pump, and that's sure to solve the problem.
To supply enough water for washing machines, dishwashers and multiple showers, larger boats often employ 110- or 220-volt household shallow-well pumps. Their plastic innards are quite durable, providing years of trouble-free service, but if they run dry for more than a few minutes, the heat distorts the plastic parts, requiring a new pump. Shallow-well pumps aren't self-priming, either. "You have to disconnect the plumbing and physically pour a quart or two of water into the pump," Murray says. Sometimes this process has to be repeated a few times.
Since shallow-well pumps are AC-powered, most boats have a backup DC pressure water system, so a spare may not be necessary. And for either type of freshwater system, in a pinch look for an equivalent saltwater wash-down pump that can be pressed into service. What about the boat owner who isn't mechanically inclined? "You can almost always find someone to make a repair," Murray says. "It's finding the part that's the problem. If it's Saturday afternoon, you're usually out of luck until Monday. You can save yourself a lot of aggravation and cost by simply carrying the essential spares."
Other Boatkeeper tips featured this month:
- More Electronics from past issues.
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