Replacing the Cooling Pump

With the rainy and windy weather, I have plenty of time to work on projects. This week I replaced the cooling pump and raw water hoses attached to it. The cooling pump draws sea water and pumps it through the three reverse cycle AC/heat units, then over the side. It was showing signs of corrosion on one of the fittings that could cause it to eventually fail. The hoses are seven years old and could have lasted awhile longer, but removing them from the pump required destroying three inches at each attachment point in order to get them off. Then they wouldn’t be long enough, so I replaced them.

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The pink color at the fitting indicates galvanic corrosion that will eventually cause the fitting to fail.

Step one, close the raw water intake, shut off the power, disconnect the electrical, remove the hoses, and remove the pump. The pump’s electrical connection is three wires: positive, negative, and ground, pretty straightforward.

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Hoses coming off.
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The third and fourth wires connect the pump’s power, while the green at the bottom is the ground.
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Pump removed from its base.

Next, I prepared the new pump for installation. This included attaching one inch bronze fittings for the hoses and rewiring the motor from 230 volt operation to 115 volt operation.

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I used pipe sealant instead of teflon tape to ensure a solid waterproof connection.
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One inch bronze fitting on which to clamp the hose.
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The water intake is 1 1/4 inches necessitating the use of a bushing to reduce it to 1 inch to accommodate the hose.
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New pump on the left almost ready for installation.
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The new pump came wired for 230 volt operation.
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The new pump needs to be rewired to 115 volt operation.
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Results of rewiring to 115 volt operation.

Surprisingly, the new pump was also wired with wire nuts, which are not acceptable for marine use due to the risk of vibrating loose. While rewiring to 115 volt operation, I replaced the twist-on wire nuts with appropriate wire connectors.

Now to put it all back together. The old hoses were held on with clamps that were perforated and beginning to corrode. As I replace hoses, I also replace the clamps with solid, higher grade stainless steel clamps that should hold better and last longer. All sea water connections should be double clamped as well.

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Solid hose clamps vs perforated.  Solid is better.
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Cutting the wire-reinforced flexible water hose.
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New hoses and pump ready to test.
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All connections are double clamped.
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Raw water intake hose directs water to the strainer to remove any large debris, then continues on to the cooling pump.
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Electrical connections complete.

With the installation complete, the only thing left to do was turn on the breakers and fire it up.

It works perfectly with no leaks! This system should be good for at least another seven years.

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