I have a 93 magnum 40 mariner that i was running in some sandy shallow water ... thought i just burnt the water pump out of it ... changed the impeller , impeller housing , lower subplate, and lower houising . the old parts looked fairly good . put it back together with new parts and i have the same symptoms that made me change it to start with . the water pumps fine out the p-hole at an idle and but as the engine speed picks up ... the water gets hotter and hotter until its steaming out of the p-hole ... them the alarm kicks on .all takes less than a couple minuites . any ideas ... ??