[Veg]

First of all make sure you are actually overheating, I'm assuming you've confirmed this and aren't going by the gauges alone. Also, assuming you have made sure there's no blockages in the sea water strainers... If so, the impellers would be the next likely culprit, I'm not sure why you'd replace the whole pump unless it's failing otherwise, but the impellers to need frequent replacement. As to your particular question, I recently had BOTH my raw water pumps replaced and including parts and labor it was in the $600 range I believe. I had them replaced because one was leaking bad from the weep hole and rebuilding it was even more expensive than replacing it. I had the other one done just for peace of mind, it was over 10 years old anyway so, might as well!