I have a Sea Ray with an 888 302 Merc Setup. My engine runs great, but
overheats after 5-10 mins under a load. I pulled the thermostat and it
was stuck 1/2 way open. Just to be safe I replaced. Once on the water
again, I had the same results, so I pulled the thermostat out just to
rule that out, and I had no change. I am confident that the pump in
the out drive is functioning because my manifolds are filling with
water, and when I removed the thermostat housing water ran out from all
of the hoses. It does not seem that all of the hoses are filling with
water, specifically the lower return hoses. When I had the housing
removed I checked for obstructions, and cleaned the entire unit that
attaches to the block in a solvent tank and then my high temp parts
washer. In my experience it is rare for a circulating pump to fail
without seizing, making noise, or leaking. I wonder if I may have spun
the impeller shaft on that pump. Does anyone have any similar
experiences, or suggestions? Like I said, I know that water is being
drawn up, but not cooling. Thanks in advance for any help!



Ryan