I had a friend with the exact same symptoms on his inboard (I know,
different animal). We concluded that it couldn't be the impeller since the
boat was in for service recently, and it was replaced. We did the same stuff
(thermostat, etc) and still had the same problem. Something made me ask him
if he had the old parts from the service, and he did. I opened the box that
held the old impeller, and all I saw was a rubber shaft. The fins were
completely destroyed. Now I'm guessing that the bozos at the shop didn't
bother to flush the motor before they put in the new impeller. I mean, all
those pieces had to go somewhere!

So...I removed the new impeller, and two of the four ports in the housing
were completely clogged with pieces of the old impeller!. I cleaned them
out, reassembled, and the boat has been fine since. I guess what I'm saying
here, is that you can't rule anything out if all else seems to check out OK.

Good luck.

--Mike

"Weldo60" wrote in message
oups.com...
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