Radiator Leak: What Causes Them and How To Fix Them

Your radiator, like many parts of your vehicle, takes a beating every day. As antifreeze circulates through the engine, the generated heat dissipates, allowing the engine to run at extremely high revolutions for long periods. Needless to say, there’s a lot of heat output. It’s incredible what a pounding your radiator takes. The cooling system must be in top shape to handle it.

If your vehicle overheats, your engine is in trouble, and many parts of your car can be damaged including the engine, gaskets, thermostat, and other parts of the cooling system. The radiator could be damaged too. It’s important to know how to fix a radiator leak before the car overheats.

Why Is the Radiator Important?

The radiator is the main part of the cooling system in your vehicle and has the purpose of keeping the engine coolant fluid at the proper level. The coolant circulates throughout the engine and keeps the engine components from overheating.

A radiator is important because it is the chief way your engine vents heat during operation. A malfunctioning radiator may cause significant engine damage caused by overheating most cars you see the billowing smoke on the side of the road is actually caused by malfunctioning radiators!

The most common cause of radiator malfunction is physical damage, which warrants a replacement of one or all of its components. Radiator function can be impaired by expired coolant or lacking coolant levels, which can be fixed via a coolant flush.

Read More: What is Radiator and How does it Work?

How to Check the Radiator?

If you are worried about how to figure out if there is a problem with your radiator or not, then this is the section for you! We have provided you with the step-by-step procedure, which should allow you to inspect the machine more comfortably.

Step-1. Park Your Car

To check the radiators of your car, they have to be parked. If the engines are on, then you will not be able to check the item. So, it is a must that your car is not on the ignition and let the engine cool off for at least two to three hours. After that, remove the radiator caps before you do anything else.

Step-2. Do a Thorough Inspection

Now, you need to turn on the engine of your vehicle. And wait for at least two minutes before you start doing anything. We do this to make sure that the coolant starts moving around inside your car.

Next, take your flashlight and point it straight towards the radiator. So, the previous step was to ensure that the coolant was flowing without any hindrance and, thus, should allow you to check whether the flow is even or not. If the flow is not smooth, then that is an indication of something wrong with the device.

A fast way of checking the radiator’s flow is to ask someone to rev while you are checking under the hood. And, when you are doing that, make sure that you are squeezing on the radiator’s hose. Therefore, if there is a clog or a fault in the hose, it will stiffen, making it quite challenging to press on the tube.

Step-3. Take Professional Help after the Test

Your car is an integrated piece of machinery, and it would be unwise to meddle with it, especially if you do not know what you are doing. Hence, if you see any faults, call the mechanic, and ask them to fix them!

How To Check Radiator Flow?

So, How Do I Know If My Thermostat Is Stuck? And, Is It Closed or Opened?

One Way Is by Checking Coolant Flow:

  • Start off with a cold engine.
  • Remove the radiator cap.
  • Start up the engine and let it idle.
  • Verify that the coolant is not flowing.
  • You can check this by looking through the radiator filler neck.
  • The coolant should not be flowing.
  • Consequently, the coolant has not reached a high enough temperature to open the thermostat.

So, if you see the coolant flowing; you have a thermostat stuck in the opened position; causing more thermostat issues. As a result, you need a new thermostat.

  • But, if the coolant is not flowing, let it run for about 20 minutes, to reach operating temperature.
  • About this time, you should see the coolant through the radiator filler neck, beginning to flow.
  • Consequently, the coolant begins to flow, because it has reached a high enough temperature to open the thermostat.

So, if you don’t see the coolant flowing; you have a thermostat stuck in the closed position. As a result, you need a new thermostat.

The Leading Causes of Radiator Leaks

The potential causes of a car radiator leak could be counted on one hand. The leading and most common cause is corrosion in the radiator. Radiators, hoses, and hose connections collect sediment and rust that over time can punch holes in the radiator.

In a few instances, weak coolant can be the cause of overheating. Poor service practices also hurt the radiator, though if serviced by a professional, this should not be a problem.

For instance, over-filling the radiator can cause leaks from increased water pressure. A bad thermostat or a heater core can also create excessive heat and pressure on the radiator.

Check the level of your radiator and the strength of your coolant while at the service station. Always check the radiator when the engine is cold; never while it’s hot.

Ask a car mechanic when you are at the garage to test the fluid. Mechanics routinely check for a radiator leak when they change the oil or do other engine-related work. Often, the invoice has checkmarks that a mechanic does routinely on a car.

If you have questions, talk to the mechanic and ask about the radiator. They’re experts, and they’ll recognize a problem as soon as they see it. Also, when buying coolants, stay away from the cheap stuff.

When it comes to getting your radiator fluid replaced, always have the system flushed. Rust and sediment collecting in the passageways and hoses can build up and cause a plug. This could cause radiator leaks and make the engine overheat. Rust literally eats holes in the radiator.

3 Signs of A Radiator Leak That You Shouldn’t Ignore

Rather than running the risk of suffering a more catastrophic failure that could leave you stranded, let’s take a look at the three signs that the leak is indeed coming from your radiator, and examine how you can best deal with the issue.

1. Puddles of Coolant

The most obvious sign of a radiator leak is a puddle of antifreeze underneath the car. Of course, not all puddles indicate a coolant problem, and not all coolant pooling is related to the radiator itself.

Take a close look at the puddle. If it’s got a green, yellow or blue tinge, it’s most likely coolant, but you can double-check by seeing if it feels greasy on your fingers.

Coolant also often has a sweet smell, which is another strong indicator that you’re not dealing with simple water condensation from your air conditioning system.

2. Locate the Drip

Your vehicle’s cooling system is composed of a number of hoses and clamps that could all be the source of the puddle you’re seeing on the ground, so the next step is to try to locate where the drip is coming from.

Typically, a radiator leak starts within the cooling fins themselves, along with any plastic or welded seam, at the filler neck/spout, or at the bottom where the drain petcock can be found.

With the vehicle’s engine off and cool, check each of these areas to see if they are wet, dripping, or showing any signs of having been wet in the past.

3. Watch with the Engine Running

Sometimes, you might be dealing with a leak that only occurs when the engine is hot and the system is pressurized. In this case, you’ll need to do the same inspection as above, but with the vehicle warmed up to its operating temperature.

Be sure to take the necessary precautionary methods and wear safety glasses when doing this, because a pressurized leak can squirt or spray out of the radiator unexpectedly. Be careful not to come into contact with any hot parts of your car.

How To Fix a Radiator Leak?

Knowing how to fix a radiator leak involves learning your options and then choosing the right one for you. You should know that the most popular and easiest way to fix a radiator leak is to use a stop-leak product that you simply pour into the radiator.

Once you pour it in, you can check your coolant level and top it off if necessary, and then get on with your day knowing your radiator leak has been fixed!

If you don’t have any stop-leak products on hand when you notice the radiator leak, there are a couple of alternative ways to temporarily stop the leak so you can safely drive to the store to get some. One option is to use egg yolks.

This may sound odd, but the eggs will congeal enough to seal tiny leaks, and the effect should last long enough for you to get ahold of a better option. Just note that you have to separate the egg whites from the yolks of about four eggs, and then pour just the yolks into the cooling system.

Then start your engine to help the eggs go far enough in the system and start to congeal. Note that black pepper will have the same effect since if you pour about half a pepper shaker’s worth of this substance into the cooling system, it will seal the leak.

Just keep in mind that both eggs and black pepper are temporary fixes and should never be used as a permanent way to stop a radiator leak. They should allow you just enough time to pick up a stop-leak product so you can fix the issue.

Of course, some radiator leaks require more serious help than only a mechanic can provide. For instance, if you check for leaks and see that your coolant is running out of your radiator, not just dripping, it may be time to take your car to the repair shop. But for most radiator leaks, a simple stop-leak product should take care of the problem!