What causes pump to overheat? Excess heat than cannot be dissipated.
Sorry. Melt in the sun pretty much hit the key points.
Trouble shooting procedures from motor university:
MOTOR STARTS BUT SHUTS DOWN (Thermal Overload Protection)
1 . Check the voltage at motor terminal. If the voltage is too high, call power company.
2 . Check amperage. If high, find out it the pump impeller was recently replaced (it could be sized incorrectly). Remember, motor Hp x SF = the maximum Hp capability of motor. This number must be equal to or greater than the pump rating.
MOTOR HOT, SMOKING OR CYCLING
1 . Check the motor’s ventilation by looking for clogged air vents or openings. Clean out all leaves, dirt and other pool and spa gunk.
2 . Compare connections and wiring to diagrams. Test the motor voltage to verify that it’s within ±10% of nameplate listing.
3 . If the voltage checks out but amps are higher than the maximum on the nameplate, inspect motor and pump for mechanical obstructions, but not before
TURNING OFF THE POWER.
4 . Ensure that the motor’s horsepower (Hp), times the service factor (SF), is equal to or greater than the pump rating (Hp x SF to Pump Rating). A full-load current greater than the nameplate listing can mean excessive pump load.
5 . Look at motor windings for damage or signs of shorting. Measure winding resistance.
6 . Check the start switch for broken contact welds or a broken spring.
7 . Check the capacitor with an ohmmeter. A bulged capacitor indicates failure on most motors. But with a Centurion, the only way to verify a failed capacitor is with the ohmmeter.
http://www.centuryelectricmotor.com/Motor-Doctor.aspx