I took the pliers back to the boat and found that when they were fully opened, the jaws bridged the hub of the impeller and slipped between the vanes on either side of the hub. I squeezed the handles tightly shut and then tapped the impeller with a hammer to jar it loose from the pump housing. Although it did take me several tries, because the pliers kept slipping off the hub, they did the job.
The pliers I bought are 10 inches overall, and the jaws open to a maximum of 2 inches, a width that can capture the hub of any impeller that’s likely to be found on engines up to 100 horsepower. The price of the pliers is a fraction of the cost of a water-pump impeller. Larger and more-powerful engines may have pumps with impeller hubs that are greater than 2 inches. Those hubs need a larger set of pliers, and they can be hard to find anywhere.
If the impeller hub is so wide that the jaws on the pliers have to be opened wide to grip it, there is a good chance that the handles on the pliers will be too far apart to hold with one hand. Since this can add to the awkwardness of the operation, you might consider bending the handles of the pliers inward, as follows: Open the handles and put a spacer between them near the jaws; a bolt works well. Heat both handles with an acetylene torch, then squeeze them together. If you don’t have the equipment, the mechanic at your local garage should be able to do this for you; it shouldn’t take more than five minutes. Because of a plier’s geometry, the farther in you bend in the handles, the farther apart the jaws will be when the handles are fully closed. That’s why it’s important not to bend the handles in so far that they can no longer firmly grip the hub of the impeller.
When you install a new impeller, be sure to check the direction of rotation and then twist the impeller in that direction as you push it on the hub. This will ensure that the vanes are bent down in the correct direction.
Finally, if you want to make replacing an impeller even easier, I recommend that you put a Speedseal cover (www.speedseal.com) on the pump. A Speedseal cover kit replaces the pump’s small cover screws—they are really easy to drop into the bilge—with knurled knobs. It also replaces the cover plate with one that requires that the knobs be loosened, rather than taken off, to remove the plate. The harder it is for you to access your pump, the more I think you will appreciate the Speedseal approach. Its features will become particularly relevant if you find yourself having to change the impeller under way and in lumpy seas
Once you’ve installed the new impeller, start the engine and immediately check to see that water is flowing from the overboard exhaust. The flow is your signal that the pump is operating properly and you can put your pliers away. But put them in an easy-to-find spot in your toolbox.
Nigel Calder is the author of many books on electrical and engine systems. His latest is Nigel Calder’s Cruising Handbook , published by International Marine.