The unsettling whiff of antifreeze--that "hot" aroma you notice while walking past the grille after a drive--is reason enough to open the hood and check it out. Getting a classic Mustang's cooling system back up to par takes due diligence--close inspection at least once a year--along with a complete flush and fresh coolant every two years along with a new thermostat. Every four years, you should install new hoses and a water pump, which can save you the inconvenience and embarrassment of a nasty boil-over.
If you see coolant leaking from the vent hole at the bottom of the water pump casting, then the seals are going bad and it's time to replace the pump.
Mustangs & Fast Fords OC in Santa Ana, California, does a lot of restoration work for customers from all over the southwest. However, the lion's share of business comes from daily and weekend drivers in need of periodic maintenance and repair. An excellent example is this '65 Mustang daily driver, a six-cylinder hardtop with a V-8 conversion that's badly in need of cooling system maintenance.
Although the owner hasn't complained of overheating, it at least has a three-row core radiator but no thermostat and an incorrect fan. Worst of all, it suffers from a leaking water pump. When we called Steve Bennett at California Mustang and told him of our woes, he set us up with a #8501B iron water pump with right-hand inlet ('65-'69) along with high-quality reproduction radiator hoses from Marti Auto Works along with hose clamps and a 180-degree thermostat.