Nissan Repair: 1994 Nissan 100nx 1.6 Overheated, nissan 100nx, coolant leaks

Question
Any help much appreciated guys. . 1994 Nissan 100nx 1.6 overheated today. . switched heater on & temp dropped. Pulled over, expansion/coolant bottle full to cap, released x2 caps, expansion & rad, no pressure ?? the Fans kicking in. Seemed to be minimal water in top/bottom rad hoses, no water movement. There is no signs of coolant leaks. A good level in rad of blue coolant, no cross contamination present oil>water>oil. flushed rad, engine block & hoses. Coolant in engine boiling. Through a process of elimination. I'm leading to a water pump fault located on the left side of engine beyond a mid belt pulley. Is there any diagrams available & could you offer any of your expert advice. Many thanks again. had car less than 48hrs.  Gr8 cheap fun!! till now Cheers ..LE$T..

Answer
Lest,

I would check the thermostat and most probably replace it.  The water pump could be defective.  But, it could be a blown headgasket.  I would replace the thermostat and waterpump first.  Unless you do a test to make sure there is no exhaust in the radiator to know for sure if the headgasket is blown.