Overview and Basic Design of Valve Stem Oil Seals

Valve stem oil seals are small relative to other gaskets and seals in an engine, but play an important role in lubrication. What makes valve stem seals different than almost every other type of seal? The answer is simple – they are designed to leak. Seals designed to leak may sound counter-intuitive, but the amount and way in which they leak is precisely controlled to achieve a specific goal.


Valve stem seals provide a controlled leak of oil to allow the valve stem to be lubricated as it slides in the valve guide. The amount of oil that passes by the valve stem seal must be precisely controlled, as too little oil causes stem and guide wears. Too much oil causes carbon buildup leading to valve seat damage, decrease in volumetric efficiency, increased emissions and excessive oil consumption.


There are two basic valve stem oil seal designs:


  1. Deflector seals – also called umbrella seals, deflect oil away from the valve stem. They are secured to the valve stem and move with the valve to shield the valve guide from excess oil. Umbrella type seals were commonly used prior to the development of positive type seals.


  1. Positive seals – attach to the valve guide boss and function as squeegees, wiping and metering oil on the stem as they pass through the seals.


AOK supplies high quality Valve Seals for cars such as Alfa Romeo valve seals, BMW vehicle valve seal and motorcycle’s, etc… In order to maintain high quality, the valve stem oil seals from AOK are all inspected thoroughly, therefore, AOK has won worldwide recognition.


If you are looking for various rubber parts, oil seal, or others, please don’t hesitate to contact with AOK via phone call or email. Let us know your requirements to find what you need.



Article Source: http://www.felpro-only.com/blog/valve-stem-seals_/

Professional Bonded Seals Manufacturer – AOK Valve Stem Seals Ltd.

AOK specializes in valve stem seals, boned seals (washers), o rings, and precision custom designed rubber molded products. AOK has distributed valve stem seals globally. The valve stem seals are widely used in automobiles, motorcycles, chemicals, forklifts and semiconductors industries. AOK’s high quality can serve customer with great satisfaction; therefore, the valve stem seals were fully inspected before shipment.

With ISO9001 and TS16949 certification and the ability of in-house mold development, AOK is capable of making various types of rubber products from mold design to finished product. Incorporation CAD/CAM system with advanced CNC machine centers and CNC lathes to design and make molds, AOK provides high quality of valve seal and bonded seal has been assured, and approved by our valued customers from Europe, North America, Asia and China. AOK is honored to have their recognition.



Aok Valve Stem Seals Ltd.

No.,24-6,Nankang 3rd Rd., Nantou City 540 Taiwan

TEL: 886-49-2263777

FAX: 886-49-2263776

website: http://www.aok-oilseal.com/

E-mail: sales@aok-oilseal.com

AOK Valve Seal Manufacturer

Established in 1995, AOK has made concrete contribution to valve seal industries for over 10 years. AOK has acquired rich knowledge and the latest technology in the automobile application field. Providing valve seals, o-ring, oil seal, usit-rings, bonded seals, bushing & absorbers and precision custom designed rubber molded products. We hope you will find our site informative and helpful to your valve seal needs. Moerover, please never hesitate to contact us.

Valve Seal

Valve Seal

Contact Information

No.,24-6,Nankang 3rd Rd.,Nantou City 540 Taiwan
E-mail: sales@aok-oilseal.com