Questions about Impeller and Water Pump

I didn't know where to put this since it's about two different brands of motor and one is broken and one isn't.

I have a 1977 Johnson 15 horse that won't pump out water. I'm assuming it's the impeller since it's never been changed. It was my dad's motor. The second motor is a 2000 115 horse Mercury that I just bought used. The Mercury runs fine and spits out water like a racehorse however, as I've been reading about impellers I've read you should change yours about every 3 years or 300 hours. So I thought since it's over a decade old it probably also needs an impeller.

I watched videos on how to change the impeller and it seems pretty simple. Drop the lower unit, change out the impeller, put the lower unit back on.



My questions are:



1.) Should I change the impeller and water pump on the 15 horse? Should I do the same for the Mercury or just the impeller?


2.) How many people change their own impeller/water pumps? Is it easy?


3.) If you change your impeller should you always change the water pump also?


4.) How frequently do you change your impellers and water pumps?


5.) What's the cheapest place to buy impellers and water pumps?

Re: Questions about Impeller and Water Pump

the impeller IS the water pump tho the pump housing can also have issues... look at it while apart and replace if cracked, melted, deformed

yes replace both impellers

Re: Questions about Impeller and Water Pump

An impeller is pretty cheap in comparison to a new engine block or a rebuild......

Re: Questions about Impeller and Water Pump

smokeonthewater said:

the impeller IS the water pump tho the pump housing can also have issues... look at it while apart and replace if cracked, melted, deformed

yes replace both impellers

Click to expand...

I see that you can order impellers or water pumps which come with the impeller.



I want to have it when I change it out and for the Mercury I don't know if I need the housing too. I'm assuming no.


And do you guys do your own? And at what intervals?

Re: Questions about Impeller and Water Pump

I change mine ever 2 years.

Re: Questions about Impeller and Water Pump

well in that case just order it all up

we can't tell you if you need the housing or not because we can't see into your engine

Re: Questions about Impeller and Water Pump

An engine with low hours usually just needs a impeller change, impeller duration will depend on manufacturers brand, you can ruin a brand new impeller by just sitting engine for long years. Pull both lower legs and have a visual inspection, then you'll know which parts needs to be changed.

Happy Boating

Re: Questions about Impeller and Water Pump

The Johnson not pumping water at all could indicate the impeller isn't just due for a replacement but might have already broken apart. They're made of rubber and the little fins can break off and plug the water tube that goes up to the engine.

It's an easy job to replace them and most likely all you need is the impeller. But while you have it apart, take the water pump completely apart and pull the water tube out of the motor to be sure (the water tube is just pushed into place, there aren't any fasteners holding it but it's probably stuck on there if it hasn't been removed in years). Even if the impeller you take out looks intact do the full check; someone might have replaced a damaged one and left pieces behind.

Re: Questions about Impeller and Water Pump

When it comes to a critical parts, such as the waterpump, I always use OEM parts rather than aftermarket ones. As for installing the pump, Youtube is a great place to find videos on most any brand outboard waterpump replacement. A engine specific service manual also comes in handy for maintenance work too.