To ensure a better experience, we save information regarding your visit to Autobutler.co.uk. Read more

The best how-to guide to your car

How to Fix a Leaky Car Radiator

20 July 2015, 09:23
Car Radiator The radiator of any car is an essential component related to the cooling system, ensuring an engine does not overheat and create a component's failure. It is an integral part of the cooling system that discharges heat from the coolant within the cooling system into the atmosphere, resulting in a cooling process known as the thermal transfer.
Get up to 3 quotes for engine repair now The coolant is then able to circulate through a hot engine and cool it by absorbing the heat and into the radiator. However, on occasions the cooling system is subjected to leaking for a variety of reasons and the radiator is often regarded as the prime cause. A leaky car radiator is generally noticed by a steady or even sharp decrease in the coolant level, engine overheating, or coolant signs underneath the car. Therefore, your first step is to check the cooling system, giving you a point from which to look for the leak. Even if you detect a leak in the radiator, it is wise to check the complete cooling system to determine whether there are other issues. Hoses, plugs, and the water pump are all items that should be checked. Look for any collapsing or swelling in the hoses, including the heater core hoses, which is part of the cooling system. Check the hoses and their connections for signs of crusted coolant on the outside, a definite sign of leaking and replace any suspect hoses and clamps. One relatively simple point of observation is the drain petcock, located on the lowest part of the radiator. Inspect it for signs of leakage and its capacity to remain secure under pressure. Your car radiator should not only be inspected for broken fins, cracks and crusted coolant leaks, but if a leak is suspected though not visible, a cooling system pressure tester should be employed. This will establish whether the radiator and its cap show signs of leaking but is an action that often means detaching the radiator from the car. Repairing a car radiator can be an easy process, or a lengthy and difficult one, which is why many motorists prefer to employ a mechanic. However, this involves a significant financial outlay, which can be prevented if you take the DIY route! Not only does it save you money, but it’s also a satisfying experience when completed. Car Radiator When the term “quick fix” is used in connection with a leaking car radiator, it is usually referring to a minor leak issue. A radiator sealant is a type of liquid or powder produced in various containers that can be added to a radiator while the coolant is cold, but with the engine running. This sealer penetrates into the various crevices of the cooling system and if a sufficiently small-sized leak is found, the sealant clogs the hole. On the car engine not operating and being allowed to cool, a semi-permanent seal is formed, providing a temporary solution for a leaking radiator. In the case of older model cars with a copper or brass radiator, repairing a leaky radiator requires the removal of the radiator. It is then usual for a radiator pressure kit to be utilised for pressurising the radiator and then immersing it in a tank of water. This action forces bubbles of air to be released from any leaks in the radiator. On identifying the leak points, the radiator is removed from the water, dried and the identified leak(s) repaired with solder and a blow torch. Leaking radiators manufactured from aluminium are also subjected to testing with a pressure kit and immersed in a water tank. Again, any leaking areas are identified and marked; the radiator is allowed to dry completely and the leaks repaired with a small application of epoxy. This type of radiator leak should not be repaired by using the soldering method, as the blow torch will frequently melt the aluminium, creating further problems. It may be necessary to subject the radiator to several immersion tests, together with reapplying epoxy to effectively seal the leaks. Should you experience coolant flowing from your cooling system, instead of a dripping process, there is the likelihood of a more severe leak that cannot be repaired with an easy fix! A close inspection will help you determine the source of the leak and whether there is severe hose damage, in the reservoir or a loose drain plug. In the event of the leak being minor and originating from the radiator, then various options can be considered for repairing it, depending on the severity. Keep in mind that whilst a coolant leak may have ceased after adding a sealant, there is always the potential for a minor leak to expand into something more serious. Make a habit of watching the temperature gauge, particularly during the heat of summer months and during hard driving spells.
Get up to 3 quotes for an engine repair job now

All about the engine/motor


Get 3 free no obligation quotes now Safety and convenience at Autobutler

Get 3 quotes and compare quotes on Engine

Quick and easy
Let us do the leg work. We will get 3 quotes from quality garages near you within 48 hours. And if it's urgent we can help you even faster.
Only quality garages
All our garages strive to give you the most accurate quote for your repairs, so please be as detailed as possible.
Need help?
If you are finding anything confusing or would like to chat about your vehicle with our in house mechanics call us on 0800 048 8195.
Get full security
All our garages are peer reviewed by car owners like you

Need help with your car?

Autobutler connects approved garages and car owners together. Our garages are ready to help you today.

Get your quotes now