Car overheating: what to do right now, and what causes it
Temperature gauge climbing? Here is the safe sequence to follow on the roadside, and the faults that most often cause overheating in Florida traffic.
The short answer
If the temperature gauge climbs, turn the A/C off and the heater on, pull over safely and shut the engine off. Never open the radiator cap while it is hot. Common causes are a coolant leak, a stuck thermostat, a fan that is not running, a failing water pump or a head gasket, and driving on an overheated engine is what turns a cooling repair into an engine repair.
Do this first
An overheating engine can go from an inconvenience to a destroyed engine in a few minutes. If the temperature gauge is climbing into the red or a hot warning appears:
- Turn the air conditioning off and the heater on full. The heater core acts as a second radiator and pulls heat out of the coolant.
- If you are in stop-and-go traffic, moving air through the radiator helps, so keeping the car rolling is better than sitting still. If the gauge keeps climbing, pull over somewhere safe.
- Shut the engine off and open the hood if you can do so safely.
- Do not open the radiator cap or coolant reservoir on a hot engine. The system is pressurised and the coolant is above boiling point; opening it causes serious burns.
- Let it cool for at least thirty minutes before checking the coolant level, and call for a tow if it overheats again as soon as you set off.
Driving on an overheated engine risks a warped head, a failed head gasket or a seized engine. That is the difference between a cooling-system repair and an engine job.
The usual causes
**Low coolant from a leak.** Radiators, hoses, water pumps, thermostat housings and heater cores all leak. A system that needs topping up regularly has a leak somewhere, even if you cannot see a puddle.
**A failed thermostat.** Stuck closed, the coolant never circulates through the radiator and the temperature climbs quickly.
**A cooling fan that is not running.** Classic sign: the temperature is fine on the highway and climbs in traffic or at idle, because airflow only comes from the fan at low speed.
**A failing water pump.** Often accompanied by a whine, a wobbling pulley or a leak at the weep hole.
**A blocked or degraded radiator.** Debris on the outside, or scale and corrosion inside from old coolant, both reduce how much heat it can shed.
**Head gasket failure.** Combustion gases pushed into the cooling system cause overheating, coolant loss with no visible leak, and often white exhaust smoke or bubbling in the reservoir. This one is both a cause and a consequence of overheating.
Why Central Florida is harder on cooling systems
Sustained high ambient temperature and humidity, plus long periods idling in traffic, mean the cooling system runs closer to its limit for more of the year than it would further north. A marginal fan, a partly blocked radiator or tired coolant that would go unnoticed in a mild climate shows up here first, and it usually shows up towing or sitting in traffic.
What gets checked
Pressure testing the system to find leaks that only appear under pressure, a combustion-gas test in the coolant where a head gasket is suspected, thermostat and fan operation, coolant condition, and live temperature data rather than just the dashboard gauge.
How we handle it at Total Performance Tuning
Overheating gets diagnosed with pressure, not guesswork. Our engine repair and diagnostics work covers a cooling-system pressure test to find leaks that only appear hot, a combustion-gas test in the coolant when a head gasket is suspected, thermostat and fan verification, and live temperature data rather than the dashboard gauge.
Central Florida heat and 441 traffic expose marginal cooling systems first, and we see the pattern constantly on trucks that tow. If the engine has already been run hot, we check compression and for combustion gases before quoting a cooling repair, so you are not paying twice.
Bigger problems stay here too: head gaskets, engine repair and full engine builds are all in-house, so the diagnosis and the fix are done by the same people. Qualifying repairs carry a minimum 12-month, 12,000-mile warranty, subject to plan terms.
**Do not drive it hot.** Call us at 352 973 5565 before you risk the engine. 4225 W Old Highway 441, Mount Dora, FL 32757. Monday to Friday, 8:30am to 6:00pm.
Common questions
- Can I just add water and keep driving?
- Water will get you off the roadside in an emergency, but it does not protect against corrosion or raise the boiling point the way the correct coolant mix does, and it does nothing about the leak that let the level drop.
- Why does it only overheat in traffic?
- At road speed airflow through the radiator comes from the car moving. At idle it comes from the cooling fan, so overheating only in traffic points at the fan, its relay or its control circuit.
- Is white smoke from the exhaust always a head gasket?
- No. A little white vapour on a cool morning is condensation. Persistent thick white smoke with coolant loss and overheating does point toward coolant entering the combustion chamber.
- How often should coolant be changed?
- Follow the interval in your owner manual. Coolant loses its corrosion inhibitors over time, and degraded coolant is a common reason older cooling systems start to run hot.
Engine not right?
Noise, smoke, overheating or lost power — we will find out why before anything comes apart.
Written by Total Performance Tuning. Last updated September 19, 2026.