How To Fix Leaking Valve Stem

A valve stem is commonly found in an automobile or bicycle wheels. It is a self-contained valve that opens in order to let gas enter a chamber (e.g. air used to inflate a tire). The valve then closes automatically and is kept sealed using pressure in the chamber (sometimes, a spring or both is used to prevent the gas from escaping). Although a valve stem is mostly found in automobiles or the wheels of bicycles, they can also be used for other applications.

There are different kinds of stem valves, and these are:

Schrader Valve – Consists of a valve stem where a poppet valve is threaded with a spring attached. This kind of valve is used on almost all automobiles and motorbike tires as well as wider rimmed bicycle tires. Also, these types of valves come in different diameters which are used in refrigeration and air conditioning systems, SCUBA regulators, engine fuel injection, plumbing and suspension systems.

Presta Valve – This is also called Sclaverand valves or French valves. This kind of valve is commonly used in bicycles and they have a narrower diameter than the narrowest Schrader valve stem.

Dunlop – Also called Woods valves or English valves. This was once popular in Great Britain but it still is used in a lot of bicycle tires in several countries.

These valves are prone to leak, especially when the weather is cold. Although only a small amount of air is released, continually doing so can lead you to have a flat tire. Sometimes, air inside the tire will try to get out of its pressurized compartment. The good news regarding a leaking valve stem is that it doesn’t take long to diagnose the problem and fix it.

Practice Safety First

It’s always best to practice safety no matter what you do. When removing the old core, debris could hit you when air is released. Sometimes, even the old core can hit you. So to avoid any danger to yourself, make sure to wear safety glasses.

Make Sure Your Car Is Parked On a Flat Surface

Parking on a flat surface makes you see the problem much clearer. Also, make sure that you have the brakes on (this is another safety precaution that you have to keep in mind).

Figure Out Where The Leak Is

Let’s say you just topped off the air in your tires but you notice that it is low again after a few days. Before you take your car to the garage, it’s best to see where the problem is. Although the problem may be because your tire has a hole in it, you can always check for a leaky valve stem first. If that is your problem, then it is quite an easy problem to fix. The tools you will need to fix such a leak are a valve core tool and a package of new valve cores.

But first, you need to locate where the leak is. To do this, you can squirt soapy water onto the valve. When bubbles form after doing so then you have a slow leak.

Replace The Valve Core

The valve core tool you need is actually four tools in one. You install and remove valve cores using the forked end. Cleaning and restoring the interior threads can be done using the tapping end. Also, the die end is used to clean and restore cap threads.

To remove the old core, you will need to jack up the wheel. But before you do so, use a lug wrench to loosen the lugs of the wheel. Then, use a floor jack to lift the vehicle off the ground.

Remove all the loosened lug nuts by hand then pull the wheel of the axle. Make sure you have an open area or workbench where you can work on the tire. Use a nail to release the pressurized air inside the tire. The valve needle inside the valve stem needs to be depressed using the nail so that air can be released.

Use the valve core tool to remove the old one then use the same tool to screw in the new one. After doing all this, refill the tire using an air pump (use the settings you normally use).

Test Out The Valve Stem

To make sure that the problem has been resolved, you have to perform a test on the valve stem. The test you will be doing is similar to finding out whether you have a leaky valve or not. So after you’ve done everything, squirt a bit of soapy water into the valve. If the fix you did was successful, you will no longer see bubbles after you’ve squirted soapy water.

Put the wheel back into the car then use the lug wrench to reinstall the lug nuts. Use the floor jack to lower the vehicle of the jack stand.

Find Out Other Signs Of Trouble

One sign of trouble could be the beginning of another. This is why you have to regularly check the components of your automobile (or any other kind of vehicle you own). In this case, when you check or fix a leak, try to check the old core threads too. If these show signs of corrosion, you can use the tap end of the valve core tool to clean the interior threads of the valve stem.

Also, don’t forget to get dirt out using a valve stem cap. After all, getting dirt around the core can also be the cause of the problem in the first place.


When air inside the tire has escaped from a leaky valve stem, the problem may have been present for a while. Since this may lead to running on a flat tire, you need to stop the escape of pressurized air. And you also need to do this as soon as possible because the last thing you want is to drive a car with an under-inflated tire or leave your car and then come back to one with a flat tire. Luckily, it isn’t that hard to find where the leak is and fix it.