Impeller replaced no water pumping(1984 mercury 9.8)

Ok so before I took the old one out it would pump ok but not consistent enough to instill confidence. So I bought a new one, pulled off the lower unit, removed the top piece of the pump assembly and there was the issue, an impeller with missing veins. I replaced this, removed the little broken peices of the old impeller, and reassembled everything. Started the motor and no water being pumped, removed the hose from the output and still no water.

So I opened it again and the impeller looked fine, spinning with the shaft, no slack. I am stumped put it back together, no water. It is blowing hot air.

There are 2 things I am not sure about, first this long copper rod comes out on to of the water pump housing, same length as the main shaft. Second, is the impeller does not appear to Align perfectly where it seats. The veins are tighter on one side than the other, like the shaft is off center.

If anyone has any ideas, please let me know.

Thanks,

Joe

Make sure the key is in the impeller and the impeller is turning correctly with the shaft. The impeller is supposed to be off center in the water pump. Not sure why but I'm sure it is supposed to be off center. Take the copper pipe out and make sure it is clear of any debris or rubber from teh old impeller. Also when you put it all back together make sure that copper pipe goes in tot he top of the water pump. Are you running it in the water or with muffs? Make sure the muffs are in the correct spot and make sure the intake is clear of any debris.

Hope it helps.

bulldog said:

Make sure the key is in the impeller and the impeller is turning correctly with the shaft. The impeller is supposed to be off center in the water pump. Not sure why but I'm sure it is supposed to be off center. Take the copper pipe out and make sure it is clear of any debris or rubber from teh old impeller. Also when you put it all back together make sure that copper pipe goes in tot he top of the water pump. Are you running it in the water or with muffs? Make sure the muffs are in the correct spot and make sure the intake is clear of any debris.

Hope it helps.

Click to expand...

This covers everything I would have suggested. Only thing I can think to add is if the impeller isn't moving and too tight...I read something some time ago (NOT TRIED IT YET), so take this with a grain of salt......squirt a little liquid dish soap on the shaft and impeller. That is supposed to lube it enough to get it spinning and will easily wash away in a few seconds. Again....I've NOT tried this, but sounds like a good trick.

Thanks for the advise guys. The impeller is seated with the key in place, and it turns freely. After reading for a while on line, it seems I need to remove the copper water tube from the waterpump and get a flashlight and insert it where it needs to be in the bottom of the motor. Then I need to reinstall the lower unit guiding the waterpump over the copper pipe. Apparently sliding the pipe attached tothe waterpump will not seat it back where it needs to be on the bottom of the motor. I will try this tomorrow.

Good luck....please post what the problem/fix is. This is good info to have for others that might encounter the same thing.

Ok I couldn't wait till tomorrow, so I waited till the wife went to sleep! Hahahah! I think i am addicted to working on this boat, before this it was building bicycles, and before that it was an off road truck! Haha!

Anyway to the facts. It took me all of 2 minutes this time to get the thing apart, and i took the copper water tube out of the water pump "receiver" and I got my 200lumen flashlight, laid down in the dark, and look up th e secondary and found the hole. Guided the copper tube into it and it kind of locks into place. I reassembed the lower unit, and cranked it(I am sure my neighbors love that!) bam! Water flowing harder than ever!

I am so please with this motor now. It starts easy runs great and now pumps water strong. Plus this impeller process is a 20 minute deal if you know what you are doing!

things I learned about removing and replacing the lower unit that most of you know, but some of you may not:

1. It doesn't matter what gear you have it in, but it seemed to be easier in forward.
2. Don't panic if your lower unit doesn't slide right back on.
3. Move the prop to get the main shaft seated, once it slides within an inch and hangs again, move your shifter very slightly in either direction and it will seat.
4. If you end up with it in the wrong gear pull it out slightly shift in the direction necessary and slide it back in at the same time.

All of the above mentioned was taken from my experience and I in no way state anything as fact.

Thanks -Joe

I changed the impeller on my 58' Johnson Seahorse at the end of last summer and it was easier than I thought it would be. Not sure what type of motor you have but I'll add to the list of things to look for.....

1. As someone mentioned earlier don't lose that keyway that locks the impeller to the shaft.
I made the mistake and spent over an hour on my hands and knees searching under my bench for the one I took out.

2. When changing the impeller make sure to change the oring on the top of the shaft or it may leak water into the block.

I now have a 15HP Evinrude and will need to change the impeller at the end of the season I'm guessing I'm wondering how much different it will be compared to the old Johnson I did.

I hear that with the key, I put it in my shirt pocket haha! I edited my title, my motor is a mercury 9.8 1984 model.