8-71TI impeller issue

[legacy45c]

I was running the other day and about two hours into my trip my stbd engine exhaust noise started to sound like a dry stack. I watched my gauge climb to 190 and I shut it down. I checked the intake for trash, debris, etc.: nothing and the strainer was clean. I cranked it up again and there was no flow. I went in on the port engine.
I then replace the impeller which looked good but after I removed it seemed to have had the bronze spline reamed by the shaft. I put in a new one and it didn't fit great so I ended up pushing it in with the cover via the screws. I then started the motor and saw that there was no water flow so then pulled the pump cover and saw that I cooked the new impeller. Now I have pulled the pump and and going to inspect it tomorrow and see if I can figure it out. Any ideas other than installing the next impeller correctly?

[captddis]

I assume you mean the cam. If so then the retaining screw is broken and not holding it in place. Remove the broken piece, ck the cam for wear and replace the screw putting some sealer on the threads and around the head before installing.

[Nonchalant1]

Check the positioning and fit of the cam. The cam is a bronze semicircular wedge that squashes the impeller vanes as they go around so water is forced out the outlet pipe. It is held between the intake and output pipes with a bronze screw and has "fingers" that match the holes in the inlet and outlet. It is supposed to fit perfectly smooth against the inside of the bore. If the screw breaks or comes out, the cam will spin in the bore and trash your pump. If the cam is in place, check to see that it's tight, no jagged, worn or sharp edged to damage the impeller and the screw is tight, but don't overtighten the screw or it'll break.

Check the pump bore. It should be nice and smooth all around. No scratches or grooves big enough to feel with your fingernail.

Check the wear plate in the back where the back of the impeller spins, It comes out and is held from spinning by a detent that fits in a slot cut in the edge of the plate. If it's badly scored, sometimes you can turn it over and use the other side, or replace it.

Check the impeller side of the cover plate. If it's badly scored, sometimes you can reverse them too, even with lightly embossed lettering on one side. If not, replace it.

If it was not leaking, the seals are probably OK.

Doug Shuman

[REBrueckner]

"....the impeller which looked good but after I removed it seemed to have had the bronze spline reamed by the shaft..."

If the center spline of the impeller has been torn from the mating surface on the pump shaft, it sounds like something is preventing the impeller blades from turning. See what's in there at the pump outlet blocking the impeller. Is the pump shaft surface ok? Some are splines, some have a flat face, maybe other shapes to match the impeller.

You can always lubricate the impeller blades for easier installation with a little dishsoap and compress the blades to fit the pump housing...with a plastic tie or hose clamp...compress and bend the blades in the correct direction!

[SKYCHENEY]

Do you have the right impellor? If the shaft does not exactly match and mate up with the impellor bore, then it could slip and wreck the impellor or shaft or both. Check the part number and make sure you have the correct one for your pump.