I have just suffered the same failure, a broken rocker bolt. And this is after having had a strip down to replace the head gaskets. I have never heard of any other engine breaking rocker bolts. How can this happen on such low mileage engines, or any engine? This is surely not a highly stressed component. The first engine on my car lasted 2000 miles and dropped a valve. The current engine has only done 11000 miles. Broken valve, blown gaskets, broken stud. Engines were built better than this 80 years ago!
