We are independent & ad-supported. We may earn a commission for purchases made through our links.

Advertiser Disclosure

Our website is an independent, advertising-supported platform. We provide our content free of charge to our readers, and to keep it that way, we rely on revenue generated through advertisements and affiliate partnerships. This means that when you click on certain links on our site and make a purchase, we may earn a commission. Learn more.

How We Make Money

We sustain our operations through affiliate commissions and advertising. If you click on an affiliate link and make a purchase, we may receive a commission from the merchant at no additional cost to you. We also display advertisements on our website, which help generate revenue to support our work and keep our content free for readers. Our editorial team operates independently from our advertising and affiliate partnerships to ensure that our content remains unbiased and focused on providing you with the best information and recommendations based on thorough research and honest evaluations. To remain transparent, we’ve provided a list of our current affiliate partners here.

What is a Bleed Screw?

Mary McMahon
Updated May 23, 2024
Our promise to you
WikiMotors is dedicated to creating trustworthy, high-quality content that always prioritizes transparency, integrity, and inclusivity above all else. Our ensure that our content creation and review process includes rigorous fact-checking, evidence-based, and continual updates to ensure accuracy and reliability.

Our Promise to you

Founded in 2002, our company has been a trusted resource for readers seeking informative and engaging content. Our dedication to quality remains unwavering—and will never change. We follow a strict editorial policy, ensuring that our content is authored by highly qualified professionals and edited by subject matter experts. This guarantees that everything we publish is objective, accurate, and trustworthy.

Over the years, we've refined our approach to cover a wide range of topics, providing readers with reliable and practical advice to enhance their knowledge and skills. That's why millions of readers turn to us each year. Join us in celebrating the joy of learning, guided by standards you can trust.

Editorial Standards

At WikiMotors, we are committed to creating content that you can trust. Our editorial process is designed to ensure that every piece of content we publish is accurate, reliable, and informative.

Our team of experienced writers and editors follows a strict set of guidelines to ensure the highest quality content. We conduct thorough research, fact-check all information, and rely on credible sources to back up our claims. Our content is reviewed by subject matter experts to ensure accuracy and clarity.

We believe in transparency and maintain editorial independence from our advertisers. Our team does not receive direct compensation from advertisers, allowing us to create unbiased content that prioritizes your interests.

A bleed screw is a screw that allows people to relieve pressure from a closed system by turning it to create a small outlet. This is known as “bleeding” the system, and when the bleeding is done, the bleed screw can be tightened to close the system back up again. A classic example can be found on steam radiators in many regions of the world. They can also be seen in pressurized systems like brakes in cars, as well as some other kinds of hydraulic systems.

The bleed screw typically has a specialized head to distinguish it from other system components. People may need a special key or tool to open it, depending on the design. This ensures that it can only be opened up when it is necessary to do so, and will not accidentally released. For radiators, a small key is commonly used to loosen the screw.

Closed systems can become contaminated over time, as the seal is not perfect. Water, air, and other materials can enter, making the system less effective and causing problems like clanking and poor performance. The user needs to bleed the lines to relieve excess pressure and eliminate the contaminant. Air in a radiator, for example, can prevent circulation of fluid, keeping a unit cold. Brake fluid can accumulate water over time, or air can end up in the lines after a service appointment.

Bleeding is usually messy, as the contents of the system can squirt out at high pressure. The user may place a bag or container around the opening to catch the spray and minimize the mess, especially if the contents of the system are potentially toxic. Once the system is fully vented, the operator can tighten down the bleed screw. It is important to use the right tool to avoid stripping it, as this could make it difficult or impossible to open up the system again in the event of a recurrence of the pressure build up.

Replacement bleed screws are available, in the event that someone strips, loses, or damages a screw. It is important to get one of the right size to make sure the seal is tight. Many companies produce standardized screws and openings, and people can bring in the old screw, if possible, to compare it with available replacements. It may also be possible to order a replacement part directly from the original manufacturer to make sure it will be the right component. In cases where it is impossible to remove an old screw, it is possible for a technician to tap a new hole in the system and install a replacement screw.

WikiMotors is dedicated to providing accurate and trustworthy information. We carefully select reputable sources and employ a rigorous fact-checking process to maintain the highest standards. To learn more about our commitment to accuracy, read our editorial process.
Mary McMahon
By Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a WikiMotors researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

Discussion Comments

Mary McMahon

Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a...

Learn more
WikiMotors, in your inbox

Our latest articles, guides, and more, delivered daily.

WikiMotors, in your inbox

Our latest articles, guides, and more, delivered daily.