Most people do not know how a radiator actually works unless they work in the motor industry or are car obsessed. So for everyone else let’s look at this question, what does a radiator actually do? The name of the motor part, radiator, is actually misleading. I always assumed that a radiator has something to do with heat (associating it with radiators used in the UK during winter to heat up homes and offices). In the motor industry, a radiator is the part that circulates liquid (a cooling agent) through pipes to cool the internal engine of the car.  Aeroplanes, trains and motorbikes also have radiators. A radiator is essential to any moving vehicle to cool the engine.

Radiators are run with coolant that passes through the radiator pipes. The coolant feeds into the engine and is heated up due to the heat of the engine. It is then fed (and is now hot) into the inlet tank of the radiator and distributed across the radiator core. As it circulates through the tubes to another tank it cools again. The cold coolant is then fed back into the engine and the cycle starts again. Radiators also have fans to blow air through the radiator to assist with cooling. Radiators are often found behind the grill at the front of vehicles to assist with airflow. So how do you know if your radiator is on the brink or in need of repairs? There are a few common signs.

Your radiator seems to be leaking fluid. If there is always a mysterious liquid on your garage floor or on the driveway after you’ve parked it’s a sign that your radiator coolant may be leaking. It is usually a sticky consistency and bright green but can be another bright colour like yellow. Weirdly enough, coolant also has a slightly sweet smell. To eliminate any other possibilities, make sure the leak is not from your water pump, hose or thermostat housing.  A sweet smell is also common with coolant. It’s important to note that coolant often flows along component surfaces in the engine compartment. Sometimes, if you have just parked your car, a leaking radiator will produce steam at the source of the leak. It is important to note that children and pets should be kept away from coolants as they are toxic. Anyone cleaning up should wear gloves and a mask. It is toxic so caution should be exercised.

Another way to check if there is a leak is to fill up your coolant tank and check it again after 2 days to see if the level has dropped significantly. Another sure sign your radiator is on the brink is your engine overheating regularly. It’s best at this point to seek help as you do not want your engine to get damaged due to overheating.

It is also important to regularly service your car and have your coolant flushed in your radiator as well. Neglecting to do this can actually be the cause of radiator damage and leaks. Coolant can actually sour, which means it becomes acidic and actually eats away at your radiator. This eventually causes leaks and irreparable damage to radiators if not addressed quickly.

Your coolant can also become sludgy which also causes significant damage to your engine. As mentioned above, the coolant is usually a green colour, red and yellow is also common. However, if there are issues with the radiator, metallic contaminants from car parts can start discolouring the coolant and make it brown or look like used oil/rusty. As it keeps circulating it becomes sludgy and does not work to cool the engine properly. The coolant is now much thicker and cannot drain properly and remains in the radiator longer. Coolant that has become sludgy must be changed as it causes extensive damage to the engine and transmission of a car.

To sum up, these are the most common issues found with radiators that have failed:

  • Internal corrosion (due to coolant turned acidic)
  • Leaking or broken coolant tanks (due to not flushing coolant regularly and leaving acidic coolant in the radiator)
  • Internal leaks caused by the transmission fluid cooler (common in automatic cars)
  • Clogged radiator core (due to sludge)


So what do you do if your car is overheating, you notice leaking fluid or you see sludge in your engine? Do not drive the car unless you are driving it straight to a radiator specialist. Continuing to drive a vehicle with a damaged radiator can cause lasting damage to your engine. Many people think carrying cold water around and throwing it onto the engine every time the car overheats is a good temporary fix. Please do not do this as it causes the engine to cool too quickly (that is the reason the radiator fluid goes through the engine slowly, to cool it down at the correct pace). This can lead to cracking on the head or block of the engine. You may not notice this damage immediately but once your engine has been damaged slightly there is no turning back. Hesitating to fix a radiator that needs repair is counterproductive due to the lasting damage it can cause when you do not repair it immediately. It can also cost you more as your radiator may become so damaged that it will need to be replaced rather than repaired. It just makes practical sense to attend to a problem like this as soon as possible. There are few important things you can note down for your radiator repair shop to make it easier for them to get your car fixed as quickly as possible. It will help them to know where to look for problems, try writing the answers to these questions down on a paper and give it to your mechanic.

  • Is the car overheating? Note down how long the car moves before the car overheats and how often it happens.
  • Does the car also overheat when idling?
  • When was the last time the coolant was flushed and replaced?
  • When was the last time the car was serviced?
  • Are there obvious signs of leaks or sludge?
  • Are there any unusual noises coming from the car?

This post was brought to you by the best radiator specialists in Durban, Silverton Radiators Pinetown. We hope it was useful and will save you some engine damage in the future! Avoid lasting damage to your car and consult us if you have any further concerns! Silverton Radiators does radiator repairs in Pinetown and Durban. They are one of the most reliable radiator shops in Durban and specialise in radiator repairs in Durban and surrounds.

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