Go looking for more impellar parts. There will be some in the cooling system. Most definately jammed against inlet to oil coolers.

I'm not looking at the engine now, so I haven't routed water flow yet.... is there a standard sequence, such as... oil cooler, then engine, then exhaust housings... or does it split and send water to multiple locations. I think i'm going to rig up some hose connections to flush lines back towards the pump, and just work back from each choke point.

Well I found some diagrams... water flow seems to go like so:

raw water pump -> oil cooler -> PS pump cooler -> thermostat housing -> then engine (if T-stat open) & exhaust risers (always flowing)

Can I assume that no impeller bits of significance would have made through the oil cooler? As in, if they made it that far, they would pass through everything else?

Or add a zinc additive, they're commonly available I've found.

Neither of my manuals state to check engine alingment. What is the benefit? Why would it move?

Get a flush kit installed in the raw water pick up hose and you can do it yourself with out fluffs!!

This engine only appears to have one oil cooler, so I'm going to assume that there is only an engine oil cooler, and no PS fluid cooler. I'm rigging up some fittings to flush back from the thermostat housing through the oil cooler and out the outlet hose for the raw water pump. I can't imagine that won't get the bits out with the pressure from a water hose. Should I also look for bits in the Tstat housing?

Is there any benefit or point to pressure flushing the manifolds out through the exhaust?

Just back flushing through the oil cooler will most likely NOT get the pieces out. They stick into the oil cooler tubes pretty hard. Do yourself a favor and just pull off the cooler and push the pieces out with a piece of stiff wire. Also, don't waste your time putting a new impeller in that old housing. get the whole kit with the new housing. I always put a piece of gorilla tape on the cups of the muffs to keep them in place.

I was afraid someone would say that. Yup, already got a complete kit with housing, this one was in pretty rough shape.

Well I backflushed this thing as a first pass, it seems to flow water fine, and there doesn't seem to be any built up pressure in the hose prior to entering the cooler (which seems to be a combo oil/PS cooler). I imagine you have drain oil, then disconnect all oil lines, and remove entirely. This looks like a PITA. Good lesson for me I guess... take care of your damn impeller - you don't want it in parts.

Do I really need to take this thing off? I'm not sure much water flowed after this thing went. Water was actually cut off (the ear muffs slipped a few inches off), so it wasn't flowing when it turned to dust, it was simply run dry. I've got 4 veins that are about 2/3 complete. The rest was dust and small bits and most all of it just fell out of the pump housing. We did try running it again after we determined we lost water flow at the pickup, but it wasn't pumping anything by that point, so I doubt it could have move much beyond the pump.

All work done, pump fixed... running and cooling like a champ.

Thanks for all the feedback folks, I was able to get it out for memorial weekend, and we had pretty good conditions:

http://i82.photobucket.com/albums/j2...psylgd5gwj.jpg

I thought of putting a large hole screen, like chick wire sized, in the hose between the raw water pump and the oil cooler(s) or put a strainer after the raw water pump(even better).. Would catch debris well..Seems these impellers are always coming apart..

Or replace raw water pump entirely with something totally different that was not such an awful design..