It’s a straightforward part of your car, but the radiator cap protects your engine. If it is leaking, your engine will overheat. In this article, I’ll discuss radiator cap leaking – causes and how to fix it.
If your radiator cap leaks, you will have problems cooling your engine. It will not release the right amount of pressure from the radiator because of the coolant leak. If you do not fix this problem immediately, your engine will overheat.
Inspect the radiator cap to see if it is worn out, damaged, or has holes. Replace the radiator cap if you notice any of these conditions. If you see any leaks in the radiator, take it to a radiator repair shop and ask them to fix the holes.
Read on to learn more about why your radiator cap leaks and how you can fix this problem.
Radiator Cap Leaking
Worn-out or Damaged Radiator Cap
While you are driving your car, there are thousands of mini-explosions per hour that occur inside your engine. Your engine produces a tremendous amount of heat while it is running.
So, it is understandable that there’ll come a time when some of its minor parts, such as the radiator cap, will have issues like leaks.
Your engine will overheat and seize up within a short time if you insist on driving your car if the radiator cap or radiator leaks. So, you need to know why your radiator cap is leaking. A common cause of this problem is a worn-out or damaged radiator cap.
Inspect the Radiator Cap
Inspect the radiator cap to see if it is damaged, worn out, or has holes. Do the same thing with the radiator. If the lid is damaged or has holes, you must replace it. Don’t worry about the cost, as this part is affordable.
One function of the radiator cap is to release excess pressure from the radiator. So, if it leaks, it hampers its ability to release radiator pressure. This can lead to the overheating of your engine.
How to Fix a Leaking Radiator Cap
Fixing a leaking radiator cap is simple. If it has holes or is worn out or damaged, replace it with a new cap. It becomes more complicated if the radiator itself is the one that has issues. No matter its problems, you must take it to a radiator repair shop for the proper fix. It’s not a DIY thing.
Other Reasons Why a Radiator Cap Is Leaking
Going back to the radiator cap, there are many reasons why it can leak. It could be because of a clog in the water pump, issues with the radiator hose, an oversupply of coolant, and many other things. Whatever the issue is, you need to go to the bottom of the problem.
How Often Should You Replace Radiator Cap?
As for the life of the radiator cap, the recommendation is to replace it after every five years. The radiator cap is constantly in contact with water and hot water. So, it is only natural that it will develop rust over time.
So, checking it regularly to see if it still holds on makes sense. If you find water pooling under your car, especially under the engine, suspect that coolant is leaking, most likely from the radiator cap or the radiator itself.
What Are the Causes of Radiator Cap Leaks?
You will likely see a leaking radiator cap in a vehicle that its owner neglects. If you are a conscientious car owner, you need to be aware of why a radiator cap can leak. What are the reasons for a leaking radiator cap?
1. Broken Radiator Cap
The most apparent cause of a leaking radiator cap is wear and tear. As I have mentioned, the engine produces excessive heat while operating. The cooling system cools down that heat.
In the process of cooling down, the hot water passes through the radiator, including the radiator cap, made of metal that can develop rust.
Over time, and if not cared for, the corrosion will build up to the extent that the metallic material of the cap will become so rusted that the whole cap breaks down. It will create a leak and cause cooling system problems, including an overheating engine.
2. Overheating Engine
An overheated engine is a real problem but can damage a radiator cap. If you examine the situation closely, you will see they are all related.
The cooling system cools hot water by passing it through the hoses, the radiator, and its fins, with the pressure released by the radiator cap, and so forth.
So, you see that hot water also courses through the radiator cap. If the engine overheats, the cooling system cannot cool the circulating hot water, so much so that the machine is affected.
If the engine is affected, what more for the radiator cap? It is not as strongly built as the engine. And so it breaks and leaks if the engine overheats – much more so if overheating happens occasionally.
3. Radiator Has White Streaks
Do you see white streaks on the radiator? That’s one cause why your radiator cap is leaking. Those white streaks indicate that some coolant has already leaked from your radiator.
This happens because the pressure inside the radiator is escaping because of the leak. The cap is no longer able to keep the pressure from going down.
4. Coolant Reservoir Overflow
When you have a bad radiator cap, the coolant will flow to the reservoir without releasing excess pressure. This leads to a drop in pressure inside the radiator. Lack of radiator pressure is the primary cause of coolant tank overflow.
5. Coolant Leak
A very obvious cause of a faulty radiator cap is if the coolant is leaking. It’s the first thing you must suspect if you notice coolant leaking from the radiator cap. Perhaps the cap is already old, worn out, or badly damaged. The best thing to do is to replace it.
Again, what causes the radiator to leak? A leaking radiator may be due to the cap being unable to release pressure from the radiator. To fix this issue, replace the damaged radiator cap.
How to Fix Radiator Cap Leaking Issue?
Buy a New Radiator and Replace the Old and Broken Cap
The most straightforward way to solve this problem is to buy a new radiator and replace the old and broken cap. Just be sure the new cap has the same pressure rating, specs, etc, as the old one.
Bring the Vehicle to a Radiator Repair Shop
However, suppose the cause of the problem is more complex and not just a faulty cap. In that case, you need to bring your vehicle to a radiator repair shop so they can diagnose the underlying problem and apply the appropriate fix.
Allow the Radiator to Cool Down Before the Inspection
But before doing anything with your bad radiator cap, remember that if you have just driven your car, it is still hot, and the water inside the radiator can burn your skin. The temperature of a hot radiator cap is somewhere between 245 to 265°F.
If you open the cap while it is still this hot, it may spray out hot water forcefully. Skin scalding is very likely under this condition.
So, give it time to cool down before touching and removing the cap from its place. It always makes sense to play it safe before doing anything, no matter how simple you think that task is.
Inspect the Cap for Signs of Crack
Once you have removed the cap, look at its condition. Is the seal still intact, or is it damaged? Are there signs of cracks and wear and tear? Is it still hard, or is it already brittle? And then, check the inner components of the radiator cap.
Check the Spring, Valve, and Plunger
Examine the spring, the valve, and the plunger. Are they already worn out or damaged? Any part that no longer looks in good condition is enough to consider the cap no longer helpful.
Remember that the radiator cap plays an important role.
So, if there’s anything wrong with any of its internal parts – the radiator cap goes to the waste bin.
How to Prevent Your Radiator Cap From Leaking?
1. Regularly Inspect the Radiator Cap
It will surprise you how easy it is to prevent this issue from hounding you all this while. Avoiding a radiator cap from leaking is quickly done by inspecting it occasionally.
2. Flush the Old Coolant After Every 100 000 Miles of Driving
Coolant can turn stale over time. So, it would be a good idea; in fact, it is recommended that you flush the old coolant after every 100,000 miles of driving.
This coolant turns acidic after being used for so many thousand miles. Acid can corrode metallic parts so fast that you can’t keep up with the rust the corrosive elements create. As you know, the radiator, including its cap, is usually made of metallic parts.
3. Regular Maintenance
Regular maintenance on the radiator parts, including the cap, will also go a long way in preventing coolant leaks. It does not take too much money and time to do this. A simple inspection and cleaning done regularly will do the trick.
Why do you need regular maintenance on your car’s cooling system? Don’t forget that this system, especially the radiator and its parts, is subjected to tremendous heat and pressure. If you neglect to care for these parts, they will fall apart, and you will be the one that will suffer.
4. Apply a Sealant
Now, in the matter of sealing – yes, it can prevent leaks. Applying a sealant to a hole will stop the leak. However, that is only a temporary fix. If you want a lasting fix, consider what I have discussed above.
If your radiator cap is leaking, your engine will overheat. The coolant leak will affect your car’s cooling system leading to the engine overheating. Your car’s cooling system will not be able to release the right amount of pressure because of the coolant leak.
You need to inspect the radiator cap for damage, holes, or if it is worn out. Replace the radiator cap if any of these conditions are present. If the radiator itself is leaking, you must bring it to a radiator repair shop to fix it.