Strange question - M50NV head bolt hole also a oil passage?

[yaofeng]

Is the head bolt slotted? I don't think so. This is sometimes used on cam bearing caps so oil comes up from the slot to lubricate the cam bearing. But the M50 engine does not use it. I don't think BMW would use slotted bolt on two components which need a lot of clamping force. I don't know any head bolt does on any engine.

[Jon K]

Ok so I had issues with priming my oil pump today - welp that's resolved and I am happy about that!

However, in the topic on bf.c, someone said that I might have issues with my head studs. I drilled the head bolt holes out from 10mm studs to 1/2" studs, which is fine. Now, someone is telling me that I need to over-bore the stud holes because they have oil passages through them! Well I drilled the holes out to 0.5250" or 0.5350" or so, but still, what the hell? I remember seeing a hole adjacent to the bolt hole in the head, but it looks like a shitty hole that is from the casting and I am not sure how it could be considered an oil passage. I've never heard of this before but that doesn't mean much. Does anyone know whats up? Do I have to worry about drilling these couple holes larger? Is there really oil through a head stud hole?

Here is what I think they're describing:

http://www.blowneuroz.com/525/headpassage1.jpg

[Jon K]

The bolt is obviously not slotted but I don't know - perhaps the stud/bolt hole is to be larger diameter... i just dont get it

[Ross]

EDIT This is in the head or the block?

[632 Regal]

the head stud boss hole, not familiar if there is an oil passage or not.


EDIT This is in the head or the block?

[Jon K]

Ross this is on the head side and there are 2 bolt holes that are DEFINITELY oil passages :(

Pulled the head out of the car in < 3 hrs and took it up to get machined tonight. So lame, but better now than never.