1996 Buick Century

[gluck2]

I have a 1996 Buick Century V6 with 56,047 miles. It has been maintained, oil changed every 3000 mi, etc. The car ran great until 189 miles ago.
The first time it happened, the service engine light started flashing. It started making a tapping noise. I immediately shut off the engine and called AAA. They towed it to a mechanic. Pulled valve covers, replaced rocker arm -pivot and stud. (the stud was broken off on the intake side.)
Car ran fine, no oil use, no noise or anything. At 102 miles, it started doing the same thing. Sent it back to mechanic and another stud was broken, another one on the intake side. (the same head) They replced the rocker arm-pivot and stud on the intake and push rod. Drove the car, ran great. no oil use, went 86 miles, service engine light started flashing. sent it back to mechanic. This time it was on the opposite head but still on intake. Mechanics do not know what is making this happen. Please help.
Thanks,
Gary

[NakedDancer]

I searched for quite awhile and found out (and the only thing I found) If the piston is hitting the valve it can cause bent valves, bent or broken pushrods, rocker arm studs to be pulled out of the head or broken, and premature cam wear. The source I found was for cam shaft instructions and it mentioned that if the valves were too tight it could cause this. I wonder what your compression tests would look like. what do your spark plugs look like? Are you using some sort of octane booster? Have you checked your engine codes.


Maybe this will get you started until someone wiser gets here to answer. Good luck.