Frequently Asked Water Pump & Cooling System Questions

How often should I replace my water pump?

A general guideline is to replace the water pump at least every two years in fresh water, or every year in salt water. Always follow the model-specific recommendations that can be found in your owner's manual. Impellers go bad regardless of how little you use your boat. It wears out if you use it a lot and dry-rots if you let it sit.

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Is it okay to fire up the motor without water before heading to the ramp?

Nope, but that's okay since it only takes a few seconds to hook up the muffs.

A lot of people say it's fine to run it for a few seconds here and there without water, but those same people usually agree that a minute or so will fry the pump. Last time I checked, seconds add up to minutes. ;-)

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Is changing a water pump easy, or should I pay a shop to do it?

That depends on your mechanical abilities. It's a pretty easy job for a qualified technician, but if a mistake is made, it can lead to an overheating problem. If you have the required tools and feel that it's a job you can handle, read through the procedure in the manual. Common mistakes would be air-leaks, leaving out parts and damaging the housing seal while sliding it over the driveshaft.

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How do I know if my motor's overheating?

The best way is to check the temperature near the top of the head with a pyrometer. The next best way would be checking the same spot, but using the correct temperature range of Thermomelt Sticks. The least accurate, but probably the most commonly used, would be holding your hand on top of the head. If you can't hold your hand there comfortably, it's probably overheating.

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Do I have to use OEM parts, or are aftermarket brands okay?

Use whichever you feel comfortable with. Quality after-market parts meet/exceed OEM specs and don't void warranty coverage.

Some people will play dirty here and say that whichever they happen to sell, OEM or after-market, is the only way to go.

There's a good chance that if you take a boat with a Mercury V6 and a little Evinrude kicker on it, to a dealership for either of those brands and tell them to replace both water pumps, one will leave with an OEM pump and the other will have an after-market one... so that should tell you something.

Also, OEM parts are generally made by the lowest bidder that meets the spec. That will often be one of the aftermarket companies.

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I changed my water pump, but it's still overheating/not pumping water. Why?

It could be a lot of things, but here are a few common causes:

Also, be sure that you're properly checking the temperature with a pyrometer or thermomelt sticks. A faulty sender could set the buzzer off, even if it's not overheating. Always troubleshoot the cooling system with the boat in the water--not on flush muffs.

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Disclaimer: Use information on this page at your own risk. Seiler Marine is not responsible for the mechanical ability of others. Never attempt a repair without the proper tools and service manual. When it doubt, it's best to take it to a pro.