Be sure to check some other obvious sources, like belts, hoses, and fluid leakage. Be sure the fluid is full, if it is half empty, the pump will cavitate, and the cooling by way of the radiator will stop.

Another place to look is the water pump itself, there is usually a small hole in the casting, and if water is coming out of that hole the seal is shot, and the pump must be replaced.

IF you Must limp home, let it cool, fill it, leave the cap loose (so it does not hold pressure), and RUN THE HEATER on full! Go directly home, and NO WHERE ELSE!