New, clean seals in clean holes with no trace of silicone or other crud in the holes. Seals well lubed with old or new engine oil so they are dripping . New pushrod tubes or old ones stretched back to length to ensure sealing pressure (see Bentley or Ratwell) . Assembled into holes and turned by hand as the cylinder head is tightened down to make sure they are in the middle of the holes, and the seams are really at the top. Air deflector plates in place before the tubes and not nearly touching the tubes - I had holes buzzed in two tubes by the edges of a badly fitted air deflector plate. I have never had a pushrod seal issue. The white ones in the 'better quality' German seals and gasket sets have always worked for me and cost relatively little.
ALL of them...use genuine seals and new tubes stretched buy hand then use a good non silicone sealant like aviation sealant*... if youre going to take the heads off you might want to check for head cracks and re-ring the pistons.. maybe more..
is this the stuff http://www.ebay.co.uk/itm/Permatex-...354266?hash=item51d09dcfda:g:c9wAAOSwstxVSeBr
Yes or this, My favorite... http://www.ebay.co.uk/itm/Stag-Well...013011?hash=item3f513ed953:g:u0cAAOSwbqpT23iX
The seals are not under a lot of pressure, and NEW seals will work OK by themselves if under pressure from a correct length tube. If you use oil you can turn them until they cannot move any more and are properly bedded in, some stickier sealants will stop that.. If they leak then somebody failed to clean up the Permatex or other crud left behind by a bodger.
I use new tubes, no oil or sealant just a little twist, never had any leak. I think Coolair do a good price on these I seem to recall.
