Suivels Auto / Symptoms / 04
Overheating
Overheating is the symptom on this list with the shortest window between noticing it and doing expensive damage. The first section matters more than the rest.
What you are seeing
- Gauge climbing in traffic, normal when moving
- Points at airflow: cooling fans, or a blocked radiator core.
- Gauge climbing at speed
- More often coolant circulation: water pump, thermostat, or a low coolant level.
- Coolant level keeps dropping
- There is a leak somewhere, external or internal. Internal is the more serious case.
- Sweet smell, or white steam
- Coolant escaping and vaporising. Steam from the exhaust rather than the bonnet is a different and more serious sign.
- Heater blows cold when hot
- Classic low-coolant or airlock symptom.
What usually causes it
Low coolant
The most common starting point, and always worth asking why. Coolant does not get used up in normal service, so a low level means it went somewhere.
Thermostat
Stuck closed, the engine cannot circulate coolant to the radiator and heats up fast. A common and relatively contained failure.
Cooling fans
Electric fans, their relays, or the sensor that triggers them. Typically shows up as overheating at low speed or in traffic.
Water pump
Fails by leaking or by losing pumping ability. Sometimes noisy beforehand.
Radiator
Can block internally with corrosion or externally with debris. Older systems that have never been flushed are more prone.
Head gasket
The expensive one, and often the consequence of driving on while overheating rather than the original cause. This is why the advice above is to stop.
Why this still needs a proper look
Overheating is worth diagnosing properly because the cheap causes and the expensive ones look identical from the driver's seat. A pressure test, a look at where coolant is actually going, and a check of fan operation separate a thermostat from a head gasket. It also matters because topping the coolant up and carrying on is how a contained repair becomes an engine replacement.
Get it checked
We come to the car.
Tell us what it is doing and where it is. We work at your home, your job, or the roadside across DC, Maryland and Northern Virginia.
Other symptoms