A radiator leak is more than just a nuisance—it can lead to overheating and cause permanent damage to your engine. If you suspect you have a leak, the following tips can help. However, if you’re not particularly mechanically minded, it’s best to take your car to a mechanic—or have your ACE Mechanic come to you—to test your cooling system.
Important Warning
The radiator, as well as the hoses connected to the radiator and cooling system, can be very hot or under pressure. Remember, never remove a radiator cap until the engine has completely cooled down. Doing so could scald you with boiling water or coolant.
Signs of a Leak
Coolant leaks can occur in various areas, and all need to be inspected for tell-tale signs. If your coolant level is dropping or the temperature gauge is rising, but you haven’t seen any evidence of a leak, try the following steps.
Visual Inspection
Open the bonnet and visually inspect the engine bay and radiator for any signs of leaking fluid. Leaks often occur around the upper and lower hose connections due to constant vibration, so check these fittings to ensure they are tight. Examine the hoses for splits or cracks. If a hose feels soft and squishy or hard and brittle, it may have perished and could be leaking.
Radiator Damage
The radiator itself may be damaged by stones or debris, which can cause a hole or crack to form, leading to a leak. Older radiators are also prone to rust, so check for rust or corrosion on the outside.
Radiator Cap Issues
The radiator cap is another potential source of leaks. If it isn’t maintaining pressure, it can cause the engine to overheat and lose coolant.
Overflow Reservoir
Coolant can also be lost through the overflow reservoir. In modern cars, this reservoir is often pressurised. If it’s cracked or leaking, the system will lose coolant whenever the engine heats up.
Check for Leaks Under the Car
Look under the car for any signs of coolant on the driveway or garage floor. Coolant is usually a bright green colour, so it should be easy to spot. If you find a puddle, check the part of the engine directly above it to locate the source of the leak.
Repairing a Leak
If you find an obvious leak, you may be able to repair it yourself, depending on its location and severity. You can temporarily tape a leaking hose with electrical or duct tape until you’re able to replace it. Adding a bottle of cooling system sealer to the radiator can temporarily seal minor internal cracks and holes, but these are short-term solutions. Proper repairs or replacement of parts are necessary to permanently fix the issue.
Pressure Testing the Cooling System
If you suspect a leak but can’t find it, try pressure testing your cooling system. A pressure tester attaches to the radiator filler neck, allowing you to pump up the system to the recommended pressure (usually listed on your radiator cap). Wait for ten to fifteen minutes—if the system loses pressure, you have a leak. If the leak isn’t visible, it could be internal, requiring professional repair.
Radiator Cap Replacement
Radiator caps can lose their ability to hold pressure over time. If your cap is old or in poor condition, replacing it might be a cheap and effective solution to your problem.
Removing Air Pockets
When repairing a cooling system leak, it’s important to remove any air pockets that may have formed, as these can cause further overheating. You can bleed the system by using bleeder valves (if present) or by loosening a lower hose until all the air escapes. Ensuring the system is bled properly is crucial to preventing future overheating issues.
Preventing a Leak
Prevention is always better than cure, especially with cooling system leaks. A little vigilance can save you from expensive engine repairs. To reduce the likelihood of a leak occurring, make sure to:
- Regularly check the coolant level and top it up if necessary.
- Keep an eye on your car’s temperature gauge.
- Have your radiator and cooling system pressure-tested and flushed periodically as part of routine vehicle maintenance.
