[Cubieman]

While doing a VCG job I noticed a 1/4" hole through the cylinder head. Using a mirror I found that there are 2 threaded holes to the left/right of this hole on the back side of the cylinder head.
I could not find any info on this via realoem.

This doesn't seem right as it simply is a hole that would allow outside unmetered air/contamination to enter the engine.

Thanks.

Edit: Looking more closely I see the VCG seals this area with the hole off, still curious what it is however.

[Wolf 335]

It's an oil drain hole.

See how it works is, when the valve cover cracks, or gasket fails, (they anticipate these things during design stage) the oil pooling in the valley will have an escape route through that hole.


It is likely a fixture locating pin hole used to position the block in the jig.

[Cubieman]

Lol, thanks.