Actually, I do have a custom fabricated stainless steel exhaust elbow (about 3-4 years old and very lightly used, and it doesn't have any small internal passages to get blocked up, like the stock Volvo cast iron elbow which corroded out inside in the cooling water passages), so I don't think the problem is there...but I'm going to check everything again --the raw water injection point on it.

It appears that the problem (assuming, again, that the raw water flow I measure is low for my engine: I still don't know) is the pump (or a blockage before the pump).

You're one of a few people so far who have told me about wear on the backing plate of an impeller pump (and someone else told me of a sealing problem on the front plate, which resulted in poor pumping and less flow). So, I'm hoping this is the problem...that is, I'm hoping I've narrowed it down...but I'll know after the weekend after a pump shop has tested my pump.

Thanks again for the info...greatly appreciated.

Jud