omc lower foot water pump holes

[SILTHUNDER77]

I recently put a thermostat in a chev 2.5L 4cylinder with an omc outdrive, my question is when does the water suppose to come out of the two holes located on the side of the lower foot assembly? should it come out when you hook up a hose at idle off the lake at low rpm's or does it come out only after the thermostat has opened above 160 degrees.. I guess my real question is how do you tell if the impeller needs changing or is moving enough water through the lower foot assembly... water does come out near the propeller, but I do not see any coming out of the<br />two holes. Amy comments appreciated, as I am fairly new to troubleshooting heating issues.. we ran the engine off the lake for about twenty minutes and a new guage we installed never read above 160 degrees, ultimately I Am trying to troubleshoot a problem where my rpm's drop from 3500 to 4000 down to 2500 where it will not go beyond until you cool down the motor. Thanks..