Last weekend I finally got the time to open up the engine and take a look. After two trips to Sears for more tools as well as a good deal of swearing I finally got my answer. The intake pushrod was short, by 0.57mm compared to the exhaust. Now you'd think that this would have been the result of a deteriorating pushrod end, or some other calamity. No actually. All I need to do is replace the pushrod. But "How" I hear you saying "does a pushrod get shorter without the ends wearing?" Here's how:
The one on the left is the original exhaust pushrod. The one on the right is the replacement I bought. They are both the same part number. Do you think that perhaps BMW figured out that the old one wasn't cutting it? Anyway, they are damn near the same weight. The old one weighs in at 11.18g while the new one is 11.90g. Seems worth the extra .72g to not dissolve into the engine oil. Anyway, I've ordered 3 more as I might as well do all 4 at once and save myself the trouble in the future. Not worth opening it all up again.