Freshwater pumps require minimal care, but they sometimes need to be replaced. Here’s how.
One of the most common plumbing complaints boaters have is a badly behaving freshwater pump. Whether the problem is noise, a leak or “no water,” some cruisers believe pumps just suck. Fortunately, these pumps don’t require a lot of attention to keep them going, but the care they do require is important, and sometimes critical.
The most common pumps on recreational boats are the diaphragm style used for pressurizing freshwater and deck washdown systems. Most of them use an electric motor that drives a rotating eccentric cam or plate to actuate three or more neoprene-capped pump chambers. Each chamber is equipped with an inlet and outlet valve to ensure a positive, pressurized fl ow of water. The only maintenance that diaphragm pumps normally require is a regular cleaning of the strainer between the pump and the water supply. The task is important because tiny bits of foreign matter can lodge in a pump’s valves and cause them to leak, resulting in a loss of pressure and excess cycling of the pump. If your boat doesn’t have such a strainer, make it a priority to install one, but make sure the strainer’s flow rating matches the pump’s rating, to avoid restriction.
Another type of diaphragm pump has a single, large pump chamber whose diaphragm is operated by a crankshaft and connecting rod arrangement mounted above it. The crankshaft is powered by an electric motor that may drive it directly or by means of a miniature rubber belt. Single-chamber diaphragm pumps tend to have a high capacity and are often found on larger boats, but their inlets must still be effectively filtered. Rubber belts, if present, should be periodically checked for wear or damage. And an extra belt should be part of your spares kit.
Normal maintenance won’t always keep a pump operating effectively. That’s why most manufacturers offer inexpensive rebuild kits for their pumps. These kits contain all the replacement parts normally required to return the pump to its original performance.