will black pepper stop a radiator leak – How To Use Them?

There are many ways to seal a radiator leak- some old school and some modern. Using black pepper to seal a radiator leak is one such old-school method. I have often faced the question; will black pepper stop a radiator leak? Yes, it will. But using black pepper should only be a short-term solution. Also, black pepper can only stop pinhead leaks.

The radiator of the car contains coolants that keep the engine from heating up. But sometimes leaks of different sizes appear in the radiator. This causes the coolant to seep out and the engine to be heated up. This situation calls for drastic measures to close the leak as soon as possible. 

However, black pepper is not the only way to seal a radiator leak. There are quite a few other ways to go about it. These methods are-

  • Commercial Sealants
  • Epoxy
  • Egg
  • Mustard

Let’s take a deeper look at the ins and outs of sealing radiator leaks by using black pepper and also other methods.

Sealing Radiator Leaks Using Black Pepper

With the advent of technology, many old-school methods of fixing car troubles have been proven obsolete by modern science. But not all old methods are obsolete. Some traditional methods still work when it comes to fixing car problems. 

Using black pepper to seal a radiator leak is one such old-school method. In my decade-long career working with cars, I have seen a lot of cars having their leaked radiator fixed temporarily using black pepper.

Despite being a proven method of sealing radiator leaks, black pepper is not suitable for use in every case. For instance, black pepper should never be used as a permanent solution for radiator leaks. Rather, it should be used until the car can be taken to a repair station. Also, nothing other than a pinhead leak should be stopped by black pepper.

How To Stop A Radiator Leak Using Black Pepper?

Now that it has been made clear that it is indeed possible to seal a radiator leak by using black pepper, let’s find out how to do it. Since sealing a radiator leak with black pepper has to be done by the driver, it’s a must that everyone driving a car has the know-how of doing this. The following steps have to be followed to do so-

1. Letting The Car Cool Down

The first step of sealing leaks in the radiator using black pepper has nothing to do with the spice. Before doing anything with the radiator, the car has to be stopped. Then a few minutes have to be taken so that the engine can cool off. To make the cooling-off process faster, the hood can be kept open.

2. Pouring Black Pepper

After the engine has cooled down, one tablespoon of black pepper has to be used. This black pepper has to be poured inside the radiator directly, instead of the backup reservoir. Then the radiator has to be filled up with an equal mix of antifreeze and water.

Once that is all done, the temperature has to be brought back to normal. The best way to do it is to drive the car for 15 minutes and then the engine has to be turned off.  After 30 minutes, the particles inside the radiator are going to swell up and seal leaks in the radiator.

3. Finishing Up

Once the car engine has been shut off for half-hour, the radiator must be checked again for more leaks. If there aren’t any leaks, then the procedure is over. However, in the presence of more leaks, the process has to be repeated with another tablespoon of black pepper. To finish up the process the car has to be driven for a further half-hour.

What Are The Other DIY Ways To Seal A Radiator Leak?

Using black pepper is not the only way to seal a radiator leak. There are other efficient ways to do it as well. Some are more permanent than others, but all of them are effective nonetheless. These are-

1. Using Commercial Sealants

Commercial sealants act just like black pepper does when it comes to sealing radiator leaks. There are a lot of commercial sealants available in hardware stores all over the country. Once the car engine is stopped and the temperature is low, the sealant has to be poured into the radiator. Then a mix of anti-freeze and water has to be poured into the radiator to fill it up. 

Once the radiator is full- the engine has to be started to allow the sealant to travel to the leak and block it. This is also a temporary method like pepper. 

2. Using Epoxy

Not all leaks or cracks in the radiator are as small as pinhead leaks. For visible cracks- Epoxy has to be used. Before using epoxy, the radiator has to be cleaned off grime using brake cleaner and a cloth. Once the area is dry, epoxy can be applied to this area by squeezing it and making it malleable. 

Unlike black pepper or commercial sealants, the car can’t be used right after using epoxy. The car should be kept as it is overnight to allow the epoxy to settle.

3. Using An Egg

As ridiculous as it may sound, eggs can indeed be used as a temporary solution to leaks in a car’s radiator. All that is needed are 3 to 4 egg yolks and then these have to be poured inside the radiator. These yolks will block off any leaks inside the radiator until they can be fixed professionally. 

4. Using Mustard

Mustard is yet another temporary fix to the leaking radiator problem. The process of using it is easy. The procedure is the same as that of black pepper. But instead of black pepper, mustard powder has to be used. 

Frequently Asked Questions (FAQs)

1. What Can I Put In My Radiator To Stop It From Leaking?

There are many ways to stop it from leaking. Some of these are permanent solutions while some are considered stop-gap solutions. One of the best ways to stop a radiator leak is to put an Alumaseal radiator stop leak and conditioner inside the radiator. Some other methods include black pepper, epoxy, mustard, etc. 

2. Does A Stop Leak Hurt Your Engine?

Some people worry that stopping a leak will end up damaging their engine in the long run. If the leaks are stopped correctly, they will not hurt the engine. For example- black pepper is a temporary solution to pinhead leaks in the radiator. If someone uses black pepper for a short time and small leaks only, they will be just fine.

On the other hand, for a long time, larger cracks cannot be helped by using black pepper at all. 

Final Words

Of all the troubles regarding a car or any other vehicle- a leaking radiator is a major one. One of the more traditional ways to solve this problem is to use black pepper. But for many of my friends and customers who regularly ask me, ‘Will black pepper stop a radiator leak?’, my answer is yes, they do stop a leak in the radiator temporarily.

However, this works only for pinhead leaks. Also, black pepper isn’t the only way to stop a leaking radiator. Some other ways include using commercial sealants, epoxy, eggs, and mustard.

Who Worked on This?



I'm the guy responsible for ensuring that every blog post we publish is helpful for our reader.

Mahir Ahmed


I'm the guy responsible for ensuring honest, informative, accurate and helpful guide to the reader.

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