Outboard - Change Water pump or just impeller

Finallybuyingaboat · #1 (**permalink**) 04-11-2008

This will be the first of 100s of questions I will have over the coming weeks as I slowly start to re-assemble my first sailboat that I slowly disassembled last fall!

Anyway, I need to buy an outboard, and a friend has an 8 hp Evinrude Yachtwin from 1989. However, when running, it does not pump very much water according to him. Would I need to replace the whole water pump or just the impeller? Not holding anyone to anything, but would it be worthwhile to try and just change the impeller before I change the whole pump?

My buddy isn't mechanically inclined,so he is of little help. How hard can this be? A few hours work if I have the manual?

sailingdog · #2 (**permalink**) 04-11-2008

Replace the impeller... however, if the impeller is missing vanes...they're probably in the cooling system and will need to be flushed out.

kelt348 · #3 (**permalink**) 04-11-2008

If its still pumping water you should be fine with just replacing the impeller. If you have any questions about it, you have to take the water pump apart to change the impeller so it might just be worth throwing in a whole new assembly. Its not all that hard to do, just take your time and dont force anything. you should replace the gear oil as well

petegingras · #4 (**permalink**) 04-11-2008

just did replace my impeller, 3.3 hp Mercury, gonna need a gasket too. I have failed in my rebuild, as i can't get the gear arm to correctly attach to the transmission arm. The manuel said, "dealer recommended". I see why, i will continue the rebuild.

Hartley18 · #5 (**permalink**) 04-13-2008

With an outboard of that vintage, not pumping much water can mean a few things, and could even be as simple as a blockage in the tell-tale.

If it were me, I'd take it to an outboard mechanic for a service and test run. Just for peace of mind when you're a few miles out with no wind to get you home again..

DrB · #6 (**permalink**) 04-13-2008

My approach is to try the easiest thing first, than work my way up the complicated ladder UNLESS I know it's the complicated thing.

Water being expelled out of the back of the motor means at least the pump is running. The impeller could be shot or as Harley18 says, it could be a bunch off things.

If it is pretty easy to pull and look at the impeller, do that first. If that checks out, and you have a nearby Evenrude Mechanic, lug it over there and see if they can give a quickly look and do a diagnosis.

Another idea is that the engine is fine and the amount of water coming out of the back is normal. Your friend may be saying that the water amount is low, when in reality it is not. The mechanic would know for sure.

DrB