How to Stop Engine Valve Seals From Leaking

Updated March 23, 2017

A leaking valve seal can contribute to damage or failure in your engine. The most common leak is oil and it will be dark brown or yellow in colour. If your oil level is low, you should check the valve cover and oil pan gaskets to see if there is a leaking seal. The valve seal leak can worsen over time, so it is important to stop it at the first sign of problems.

Add an oil stop-leak additive to your engine for a temporary fix. Add it in the oil filler tube, just as you would motor oil. An oil stop-leak additive is designed to give valve seals extended life by causing them to swell. The swelling of the seal may temporarily stop a leak.

Use a high mileage motor oil. These oils have seal conditioners in them to stop or reduce leaks. The oil is designed to keep the valve seals soft and pliable in an effort to reduce corrosion that is caused by ageing.

Replace the leaking seal. Remove the cover over the seal. Scrape away any build-up that has occurred on the area where the new gasket will go. Put gasket sealer on both sides of the new gasket if it is made of cork. If it is made of rubber, you will not need to apply the sealer. Position the new gasket into place in the spot where the old one was. Put the cover back on the new gasket and tighten the bolts.


High mileage motor oil is for cars with over 75,000 miles.


An oil stop-leak additive will not stop a major leak or repair a broken gasket or seal.

Things You'll Need

  • Oil stop-leak additive
  • High mileage motor oil
  • New seal
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About the Author

Tyler Ellington is a freelance journalist whose work consists of a wide variety of topics. A freelance journalist since 2007, Ellington typically spends most of his time writing about sports, business and technology. His work has appeared on various websites. He earned his master's degree from California University of Pennsylvania.