BMW: cylinder head on 1999 323i, dual overhead cam, guide bolts

Question
Hi Josh,
I have a few questions really and I might be over my head but I've done Anerican cars before. The car overheated quite badly and I hope it's fixable. I've been told by a mechanic that there is only 25lbs of compression in each of the 6 cylinders. He also wanted to send me to an import shop and sell me a 7500.00 rebuild I could find on the net for 5000.00. Cost says I need to repair it myself and I'm at the cylinder head. I haven't done overhead cam before and wonder if there's anything special or tricky, looks pretty straightforward. I'm at the vanos and it's out except for the guide bolts and I was wondering if I should be cautious of something here. I intend to have the head magna fluxed and expect it to be warped, depending how bad either fix or replace. Also may be bad rings, also stuck or needing new valves and valve guides. Any help would be greatly appreciated, thanks, Don

Answer
Don,
 I think the person who quoted you $7500 is out of his mind.  Dont get me wrong, these Dual overhead cam engines are more expensive than the older ones, however the internals a very similar.  Apart from the head, the rest of the engine is very similar to an older BMW 6 cylinder.  You should be able to rebuild for $1000 (that's with new pistons).  The head is a little more tricky, you want the valves to seat well, and that takes some skill.  I'm confident that you can do it, however it's a job to do.  Unfortunately I'm not the authority on these engines (M52).  I work on the older M20 6-cylinder.  

 I would definately have the head magnafluxed as you said, and they will probably end up decking the head to get it flat again (if it's warped).

 Good luck,
 Josh