Why your hot rod runs hot in traffic
If the temperature climbs at a stoplight and falls on the highway, investigate airflow before throwing another radiator at it.
Record when the problem happens
Note ambient temperature, road speed, gauge reading and whether the rise occurs at idle or under load. Verify the temperature measurement and coolant level using the service procedure on a cold engine. Never open a hot cooling system.
Inspect the airflow path
Check fan direction, shroud position, radiator obstruction and whether air can bypass the core. Electric-fan advertised free-air CFM is not the same as airflow through a radiator. Compare the fan manufacturer’s application guidance and electrical load.
Treat the electrical system as part of cooling
A fan needs appropriate wire, fusing, relays and a dependable ground. Size the circuit for the manufacturer’s running and starting current. An undersized charging system may struggle with fans, lights and ignition at idle.
Look beyond the radiator
Incorrect timing, trapped air, a damaged cap, belt slip or other engine problems can contribute to overheating. Follow the engine and cooling-component procedures. A larger radiator cannot repair an underlying mechanical fault.
Reference: Manufacturer technical information ↗