Good news....

I think the more common crack found is between the cooling jackets and the piston crown on the exhaust side - although check the intake side too. I don't have a picture handy, but there are several online.

Cam bearing surface. Too far gone?

Another cam journal shot. Should I hit the yard for a replacement? Anyone have any extras with the trays and caps?

This is quite common - just search M54 cam scoring - Although your cams look a little worse than average in my opinion, particularly on the intake side.

There in't much you can do..a few folks have suggested polishing them, which won't take out all the groove, but you can't really grind them because BMW does not sell oversize cam trays and caps.

From what I can tell, most people just leave them as is.

If I were in your shoes, I would ask my machinist his thoughts. ( I actually have two I can ask questions of). I also suggest you consider getting another 3.0 head with cams and cam trays at a junkyard if you can do so cheaply. Chances are the cams will also be scored, but maybe less. It must be a 3.0, the 2.5 uses different cams - at least a diff intake cam.

So this reminds me of a problem with an outside the box solution on US Navy submarines.

The bull gears that convert the fast output from the steam turbine down to the typical 50 RPM at the shaft are so big and expensive the Navy will lease them.

Anyhow when one of these irreplaceable gears gets damaged, say a tooth breaks off 2" in on an 10" wide gear, the solution they came up with was to precisely grind a gap on both the bull and drive gears effectively making a pair of parallel gears, 2" and 7.5" vs a solid 10.

That same principle applies here.

It should be worth polishing the bearing but you can't reduce the size. If you turned on a lathe and precisely cut the rough spots to a smooth surface the oil should channel though there just won't have much support in that place but won't cause problems with the oil flow to the high spots by having a rough surface. Basically effectively makes the bearing surface not as wide.

Try to find somebody that's done such and the success stories.

I know that with most bearings once there's a rough spot it propagates and that's my theory on how to slow it: remove the rough spot as possible.

Traded messages with a BMW-trained, now independent, tech on the E46 forum. He does a lot of head work.

He made the additional point that the cam trays and caps are aluminum, while the camshaft is hardened, cast iron. Much of the damage to the intake cam journal - Not all of it - is aluminum material transferred from cap to journal. He did confirm that it is quite common.

He said you could polish the journal, and either have the cam trays and caps line bored OR you can replace a cap or two with a good condition used one assuming the installed, lubricated cams rotate freely with non-original caps.

Another update... I’m polishing the valves on a lathe to clean them up before the machine shop gets them. I asked the machinist about numbering them. He said it wasn’t necessary if you cut the seats and turn the valves. I don’t remember if he also included new valve guides in the same sentence. Here is a before and after shot.

It’s also a great way to make sure they’re not bent. I don’t have a lathe so I used a drill stuck in a vice

Note to self...Remove the exhaust manifold first when you take off a cylinder head at the junk yard. You won't have all the resources that you do at home and at the end of a couple hours you don't want to hit the wall and settle for the cams and the carriers only.

Well now you have a reason to go back and get it. What was the big obstacle? downpipe connection?

Taking the exhaust manifold off with engine in car is no day in the park either.. Actually I am a little surprised they were still there. The junkyards in my area typically remove them because they have the cats.