valve stem oil seals

[dpearson]

im rebuilding my 1098 engine at the mo, it had valve stem oil seals on the valve guides but the parts book shows that an o-ring should be fitted, my valve guides were very worn is this because the seals that were fitted stopped any lubrication to the valve stems, im just wondering which method is preferred by other owners.

[simmitc]

The original design had the O-rings. The latest design, usually found on recondioned heads (especially "lead-free") uses a different guide with a small grove into which the rubber cap type seal fits. In my experience the latest design is far superior for controlling oil; and in many thousands of miles daily driving I have not had a problem with guide wear. Conversely I have had the old style exhibit serious wear on one guide out of 8, so I conclude that wear is just a matter of luck.

[bmcecosse]

The top-hat seals had likely been fitted in an attempt to stop excessive oil pouring down the worn guides. The O rings were a very basic attempt to keep the oil away from the stems...... Fit modern guides -and likely the valve stems will be worn too - and the top hat seals. Some (including me) only fit the seals to the inlet guides.