Spark plug tubes

[Gelbster]

Note on lubricating O ring seals -see link above.
Use silicone grease. Don't use engine oil because it is not as slippery,nor as thixotropic.
Do NOT lubricate the entire seal,nor the groove in the tube . Fit the seals to the tube DRY .
Lubricate just the leading edge and outer surface of the seal sparingly. Otherwise the seal will twist and roll as you push it in the final 2mm. That would probably leak .If the seal slides out of the groove(because it is oily) in the tube, it will also leak.
Measure the leading edge groove in the tube for out of round before you fit the seal. A difference of 1/2mm may cause a leak.
If you use sealant of any sort, you will be doomed to leaks and worse.

[JFP in PA]

Originally Posted by Gelbster

Note on lubricating O ring seals -see link above.
Use silicone grease. Don't use engine oil because it is not as slippery,nor as thixotropic.
Do NOT lubricate the entire seal,nor the groove in the tube . Fit the seals to the tube DRY .
Lubricate just the leading edge and outer surface of the seal sparingly. Otherwise the seal will twist and roll as you push it in the final 2mm. That would probably leak .If the seal slides out of the groove(because it is oily) in the tube, it will also leak.
Measure the leading edge groove in the tube for out of round before you fit the seal. A difference of 1/2mm may cause a leak.
If you use sealant of any sort, you will be doomed to leaks and worse.

And be very careful with aftermarket tubes, many of them vary wildly in both size and concentricity as users have found to their dismay. Cheap ain't always a positive.