TimO'Brien

So I was thinking after completing the tensioner seal job - what the hell is the purpose of those stupid half-moon seals (one on the valve cover gasket and the other separate under the tensioner seal)? Why wouldn't Audi just engineer the top of the head to be flat so these seals wouldn't be needed? Why leave an opening port for oil to leak after the seal fails?

The half-moon openings seem to serve no purpose... other than perhaps an engineered service requirement (like the timing belt rather than chains).

4Driver4

Gotta drill the hole for the camshaft somehow.

TimO'Brien

Not sure I follow. There are holes in the front where the cam seals go and it's not like it couldn't be machined without the holes since the valve cover comes off...

Audiboy

most car manufacturers use the same practice. As 4diver said gotta drill it. More of how the machine it. Half moon seals are pretty common to other makes

4Driver4

The holes, one for each cam, are bored strait through the head. The cam caps are bolted in place, and the drill passes through the head. One the way out the back, it cuts the half moons.