Frequently Asked Water Pump & Cooling System Questions
Common questions about marine water pumps and the cooling system. Feel free to suggest a question that you feel should be covered here.
How often should I replace my water pump?
Is it okay to start the motor without water before heading to the ramp?
Is changing a water pump easy, or should I pay a shop to do it?
How do I know if my motor's overheating?
Do I have to use OEM parts, or are aftermarket brands like Sierra okay?
I changed my water pump, but it's still overheating/not pumping water. Why?
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How often should I replace my water pump?
A general guideline is 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. Use it and it wears out... let it sit and it dry-rots.
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Is it okay to fire up the motor without water before heading to the ramp?
Nope. Besides, it only takes a few seconds to hook up the muffs, right? I could never figure this one out. 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. Wouldn't they also agree that seconds add up to minutes? ;-)
Not to mention, doesn't the owner's manual clearly state to never run it without water?
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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 it's too hot to touch, 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. Some shops might not give you an option. 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.
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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 these are a good place to start looking:
- Pump improperly installed or defective.
- Air leak.
- Clogged water tube.
- Clogged passage in the powerhead.
- Clogged or defective thermostat.
- Some outboards have a rubber grommet at the top of the water tube that can melt shut from overheating.
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 this information 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... take it to a shop.
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