I Idled across a shallow sandy bottom,sucked sand of course,nose cone pick-up.Temp started climbing at high speed ,shut it down just before 180 deg. Limped it back to the trailer.I'll start at the begining of my attempted remedies.Pulled all hoses,pulled t-stat housing flushed clean.flushed fuel cooler,and oil cooler-which i found enough pebbles to plug those small holes about 70%.Okay, so then I purchased the sea pump impellar/body kit and rebuilt it.After back flushing the block for what seems like days now,it's been on the garden hose running and in the lake and the right side still seems considerabley hotter than the other.The temp still climbs and would go past 180 if I kept on it.I've also disassembled the exhaust riser/manifold,It's clear just expected rust.I also used compressed air in the water jacket drains to try to agitate the sand.I'm almost positive that when the sand was pumped into the engine the pebbles that half-assed plugged the oil cooler, restricted the flow enough that the finer particles packed into smaller water jackets or in the head,and could not flush away.Obviously a sea strainer may have helped.I've run the motor with the plugs out, it seems to be clear.When coming off plane and back to an idle I noticed some steam from the right exhaust,gotta be starving for water flow somewhere.When I start the engine cold ,the temp slowly rises to about 160,then I can see on the gauge that the stat opens and temp drops to 140-150.Like I said it will climb at high speed,past180.It's kinda weird cause we idled through a half mile long channel earlier that day and the temp sat at 120-130.Now once up to temp it wont go below 150. Both sides are dumping the same amount of water just the right side gets hot.The right exhaust manifold gets much, much hotter.I really wish I could figure out the flow path of the t-stat housing.My next step will be a new stat,even though it opens ,it may not be all the way.After that I'll pop a frost plug out towards the back and check for a blockage.I really don't want to pull the heads.Anyone knows any thing that I have not covered,PLEASE REPLY, WE HAVE A POKER RUN SATURDAY.Thanks Dave