When you say "casting below" do you mean the casting of the cam tower? If I remove everything and start over, and flip over the tower I should see damage?
No.
I am talking about the bolt bore down into the head itself. The bolt holes are not supposed to be bottomless, i.e. exposed to the atmosphere like the bearing cap stud holes are. The longer bolts can "punch out" the bottom of these bolt holes if torqued hard enough, exposing the bottom of the bolt bore to the atmosphere underneath.
No big deal you say? I would not have thought so either except that I still have oil stains on the shins of more than one pair of jeans from the
profuse oil leak that results from this condition. If you look down through the bolt bore through the cam tower you will see that the oil passage to the cam bearing passes through the bolt bore itself. So unlike the bearing cap studs, the bearing cap bolts have
oil under pressure behind them. This oil under pressure will easily push past the bolt threads below. You can test the integrity of these bolt holes by merely filling them with your fluid of choice (oil works for me) and verify that these bolt holes in the head will hold fluid. Any that don't will leak down onto the head below.
I discovered this by accident, after replacing the cylinder base gasket, piston rings, o-rings, head gasket, etc., of a newly acquired (non running) project, only to be rewarded with oil soaked shins on first shakedown. After pulling the engine
yet again I was staring at the top of the head, once the cam and towers were removed, contemplating removing the head
yet again, when I noticed three of the four bolt holes had filled with oil (cleanup had not yet begun after removing the cam towers). It was upon further inspection that I discovered the bottom of one of the bolts holes was exposed to the atmosphere below, and continued inspection revealed the cam bearing oil passage in the cam tower passing through the bolt bore. I was able to correct the problem without any further disassembly and finally got it on the road without spewing its contents onto my shins.
To correct the problem I used another threaded stud at this location and doped up the bottom threads with thread sealer prior to putting the cam tower in place. I took this approach for two reasons:
1) If I were to merely treat the bolt threads with sealer there is the risk of scraping thread sealer off of the bolt and packing the cam bearing oil passage full of thread sealer as the bolt is inserted.
2) Hopefully the next guy will see the stud where a bolt should be and ask himself "Why'd he do that?"
This makes it a little tight getting the cam back in, but not impossible.
