help with stuck Vanos 8mm hex caps

[Russianblue]

here is the part in question:

https://youtu.be/6bmYj5ZOAz4?t=329

https://www.fcpeuro.com/products/bmw...ug-11361438338

The T30 torx screw is underneath this cap and that one IS reverse thread. This is standard thread.

I tried a bit of heat, but firing that MAPP gas with all that oil and fuel residue made me a bit leery. I previously tried some penetrating lube but wasn't sure that was doing much good given all the oil that area is exposed to already. In retrospect it did nothing.

I then read about the dremel and chisel method. I cut a slot at about 9 oclock on the cap with a dremel disk and got a screwdriver in there and started banging it straight down. Nothing doing.

After mauling the cap and making zero progress I reasoned that these caps are going to have to be replaced regardless. Moreover, the replacement caps are cheap. Anyway before I resorted to drilling/cutting the entire thing I figured I'd at least go ahead and give the breaker bar all she had until the hex bit stripped out the hole.

Well, I suppose I got lucky. All I will say is that it took what had to be upwards of 100 ft lbs of torque to snap those things loose. I had two hands on it and pulling damn near as hard as I could. No lie. It takes less pressure to loosen my wheel lugs. This was an 18 inch breaker bar/extended socket.

After a deafening SNAP!, both sides came loose. My hex bit was buried so deep in the metal that I had to put the cap in a vice to hold it and reverse ratchet the hex bit out. No way those same parts are going back in.

Mind you, i'd rebuilt this VANOS about 2.5 years ago and torqued those caps myself. I was meticulous with the torque values. My hunch is that the oil that got under those caps when I changed it may not have been there from the factory and varnished up with the heat of the cyl head. When I reinstall, I am going to clean the hell out of those mating surfaces first. I don't think the threads were seized. I think the washer was frozen to the surface with gummy baked oil/varnish. Just a theory. Could be completely incorrect.