while replacing the impeller on a new to me yamaha f20, I took the cup off and holy hell! The impeller is completely demolished.
I have the water pump put back together but before putting the LU back on what’s the likelihood of impeller bits being lodged in the pickup tube?
if high, what’s the best method to ensure no debris in the pickup?
I would imagine the remnants would go out thru the exhausts…just a guess
reach out to smack or jc because they make a living at it
I would definitely replace the cup and plate(entire assembly) on that one. Start new.
Look up the tube, see if there are any chunks lodged up there. Or better yet, use a bore scope to inspect if you know someone that has one. The ones for sale on Amazon will work. Not much you can do in the engine. Small pieces should pass.
Are the broke off chunks hard? If so, the water pump over heated due to lack of water. Rubber will harden when subjected to heat beyond its design capability. Friction from running dry on the cup will create excessive heat on the rubber. The water in the pump acts like a lubricant and cools also.
Good luck
I agree, listen to Smackdaddy and JC.
Smack is gonna tell you he is running the same impeller for 13 years…JC is gonna tell you to replace the whole thing every year. There! 
It’s funny because it’s true. I’d still be running that impeller after over eight years but I already had a new kit and the pump apart so I replaced it all.
On stock outboards there’s no reason to change the impeller or pump as often as people do unless water pressure and engine temperature are telling you the pump is losing efficiency. Lots of guys don’t even have a water pressure gauge or monitor engine temperature…blows my mind. Changing the water pump when there is no issue is the equivalent of changing your vehicle engine oil after a thousand miles and is still transparent when you drain it…Changing the pump annually is probably good preventative maintenance but if you guys are doing that it’s like throwing money away.
To the OP, I would replace the pump and run the motor. If you notice cooling issues you may have impeller bits that made it into the powerhead cooling jacket. I’ve seen many pumps go nuclear due to operator error and not had any rubber get up in the cooling system and I’ve also seen a few where just one or two vanes came apart and the rubber made it’s way up. Most of the time the rubber pulls a Houdini and you’ll never locate the pieces. Some are a mystery.
pull the thermostat some of them may be there
Yep! This is one thing @Smackdaddy53 and I disagree on! I say replace the impeller and inspect housing annually mostly because it is truly cheap insurance and well… quality control just sucks anymore.
Extended water pump life is only with my system, not stock. I’m still down with annual or bi-annual water pump inspections on stock outboards.
