87 van coolant flush

87 toyota van 2.2l 2wd continues to overheat, but no coolant leaks exist except for overflow tube on resevoir spews when car overheats, thus losing coolant. Don't see any water in oil. I've removed the thermostat in order to further troubleshoot. Replaced radiator cap. I intend to install a Tee in heater inlet hose to do a reverse flush, but am not sure of which hose. Where is it located. Further, I replaced the water pump during cooler winter months and am wondering if I did something wrong. Can't find a picture to tell me, but is there any chance I could have installed propeller backwards? Have looked down radiator cap upon first starting car and there is fluid movement/pressure, but can't tell if it's flowing in correct direction (towards upper hose). Any way you can think of, short fo pulling water pump again, to eliminate that as the culprit as opposed to a blockage in colling system.