alil blockage?

[Kajun]

update:....went out and did a back flush through the thermostat housing tonight..... :o holy beach balls batman...a ton more sand came out...took off LU and took apart waterpump...full of sand also...everything is clean and flushed now and i got the next 5 days off!! but of course my luck hits again ....ALL marine parts stores in the area are closed till jan 2nd!! so i have to wait till then to get a waterpump gasket! :(