Nothing disrupts a journey more than seeing that rising temperature gauge or steam from beneath the bonnet. At Bromley Vehicle Test Centre, we see overheating engines frequently and understand that identifying car overheating causes quickly can save money, time and engine health. In this comprehensive guide we’ll break down the most common reasons your car overheats, what to look for, and how our expert team in Bromley can help you address the issue safely and professionally.
If you’d like personalised advice for your car, feel free to call us on 020 8460 6666 or drop us a line at .
Get your vehicle inspected today for peace of mind and lasting performance.
Engine Overheating – Understanding the Basics
Put simply, an engine overheats when heat is being generated faster than it can be dispersed. Cars are designed with a cooling system to control engine temperature, but if any part of that system fails, heat builds up and trouble starts. Cooling system faults, low coolant levels, or airflow issues can all lead to engine overheating.
At Bromley Vehicle Test Centre, we combine decades of experience with up-to-date diagnostic tools to pinpoint exactly what’s gone wrong. We emphasise transparency and clear explanations so you understand what’s happening under your bonnet.
Car Overheating Symptoms – What You Might Notice
Most drivers don’t ignore overheating for long, because symptoms tend to be unmistakable:
- Temperature gauge climbing into the red zone.
- Steam or heat waves rising from beneath the bonnet.
- Strange smells such as sweet syrup (coolant) or burning.
- Loss of engine power or the car entering protection mode.
These signs often signal car overheating symptoms that should prompt immediate action. If you see any of these, safely pull over and contact our garage team for advice.
Quick Safety Tip
Never open a hot radiator cap immediately – steam and pressure can cause serious burns. Allow the engine to cool for at least 30 minutes before checking coolant levels.
Why Is My Car Overheating – Top Causes Explained
Let’s explore the leading answers to the question why is my car overheating. We’ve grouped these into the top five contributors:
1. Low Coolant Levels
The most common culprit behind overheating problems is low coolant. Coolant, also known as antifreeze, absorbs heat from the engine and carries it to the radiator for dissipation. If levels fall too low due to evaporation or leaks, the cooling process falters.
Possible reasons include:
- Leaks in hoses, the radiator or water pump.
- Old or degraded coolant losing effectiveness.
- Faulty radiator cap, losing pressure.
If left unchecked, low coolant can quickly lead to overheating and engine damage.
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2. Thermostat Failure
The thermostat regulates the flow of coolant based on engine temperature. If it sticks shut, hot coolant is trapped in the engine and cannot circulate. If stuck open, it doesn’t allow the engine to reach optimal operating temperature. Both situations contribute to engine overheating.
This is a common problem in temperamental UK weather, especially if a vehicle hasn’t been regularly serviced.
3. Water Pump and Circulation Issues
Your water pump is the circulatory heart of the cooling system. When it fails due to wear, blockage or damaged bearings, the coolant stops moving effectively. This dramatically increases the risk of overheating.
Signs of a failing water pump include:
- Whining noises from the engine bay.
- Coolant leaks around the pump housing.
Without proper coolant circulation even a correctly filled system can overheat.
4. Radiator and Airflow Problems
The radiator relies on good airflow to cool the engine coolant. If the radiator fins are clogged with debris, crushed by damage, or if the radiator fan isn’t working, the engine’s heat cannot escape as designed.
Blocked airflow combined with heavy traffic or slow-moving journeys dramatically increases the likelihood of overheating.
5. Head Gasket or Engine Oil Issues
A failing head gasket can allow coolant and combustion gases to mix, reducing the cooling system’s effectiveness and causing overheating. Low engine oil or poor-quality oil can also make the engine run hotter due to increased friction.
These issues are more serious and often require prompt mechanical intervention to avoid major engine damage.
What to Do If Your Car Is Overheating
If your temperature warning light comes on or you notice steam or odd smells:
- Pull over safely at the next opportunity.
- Turn off the engine and hazards on.
- Wait at least 30 minutes before touching the bonnet or fluid caps.
- Check coolant level once cool — but never open a pressurised system hot.
- Contact our team if you’re unsure or the issue persists.
Opening a hot cooling system can cause severe burns, so patience and caution are key.
How a Mechanic Can Help
When your car overheats, a trained mechanic does more than just top up the coolant. At Bromley Vehicle Test Centre, our expert team:
- Performs full cooling system diagnostics.
- Checks for coolant leaks, hose integrity, thermostat function.
- Uses advanced tools to trace head gasket issues or airflow restrictions.
- Offers transparent quotes and honest advice, with no hidden charges.
With decades of experience and a strong local reputation, we help drivers not just fix the problem but understand what caused it in the first place.
Cooling System Flow and Common Fail Points
| Cooling System Component | Main Function | Common Failures |
| Coolant reservoir | Holds coolant | Low level, leaks |
| Thermostat | Controls flow | Stuck open or closed |
| Water pump | Circulates fluid | Pump failure |
| Radiator | Heat exchange | Blockage, damage |
| Hoses | Fluid transport | Cracks, leaks |
Why Regular Servicing Matters
Regular engine servicing, including coolant checks, fluid changes and system inspection, can prevent many car overheating causes before they escalate. This protects engine longevity, improves safety, and can help lower repair costs. Our comprehensive servicing and diagnostic checks at Bromley Vehicle Test Centre are designed to catch issues early.
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FAQs – Engine and Overheating Queries Answered
What does it mean when the engine overheats?
It means your engine’s cooling system is not removing heat as fast as it’s being generated, often due to a cooling system failure or low fluids.
Can I continue driving if my car overheats?
No. Continuing to drive risks serious engine damage. Pull over, switch off the engine and call for help.
How often should coolant be checked?
Coolant should be checked at least every service or when there’s a warning indication. A full system flush may be needed per manufacturer intervals.
Is overheating covered by MOT inspections?
An MOT checks overall roadworthiness, but mechanical overheating issues often need a separate diagnostic and repair beyond routine checks.
Do you offer emergency inspections?
Yes, contact our team for immediate advice or to arrange a prompt inspection at our Bromley garage.
Quick-Review of Overheating Causes
| Cause | Likelihood | Immediate Action |
| Low Coolant | Very common | Top up and check leaks |
| Thermostat Fault | Common | Mechanic inspection |
| Water Pump Fail | Common | Professional repair |
| Radiator Blockage | Moderate | System clean |
| Head Gasket Issue | Less common | Urgent mechanic |
Final Thoughts
If you’ve noticed overheating signs or have concerns about your cooling system, book a diagnostic check with Bromley Vehicle Test Centre today. Call us on 020 8460 6666 or drop us a line at .