M20S Driver Posted January 20, 2015 Report Posted January 20, 2015 The exhaust stud came off from the cylinder head while my mechanic was removing the exhaust flange (see pic). Has anyone done this repair and how intrusive is it?
carusoam Posted January 21, 2015 Report Posted January 21, 2015 Not familiar, but I see the threads look a bit out of shape at the tip of the fastener..? Looks like there may be more to the story? Best regards, -a-
kmyfm20s Posted January 21, 2015 Report Posted January 21, 2015 I have seen my mechanic fix one once and I think he used an oversized stud. Im sure it depends on how much Aluminum came out with the stud.
jetdriven Posted January 21, 2015 Report Posted January 21, 2015 What's with that piece that's trapped on the stud. Looks like something that's pressed in the head. I'd investigate further.
cliffy Posted January 21, 2015 Report Posted January 21, 2015 I believe it is a locking ring for the stud in the head. The stud is screwed in to a certain depth and the insert is slipped down on the stud and driven into a counter bored hole at the stud entrance to secure the stud from turning. The teeth on the stud engage the inner ring teeth and the outer ring teeth are driven into the aluminum head material. Obviously the outside nut was frozen to the threads and the mechanic applied Charles Atlas torque trying to break it free and succeeded in breaking free not the nut but the stud securing items. You may be faced with cylinder removal and head welding
M20S Driver Posted January 21, 2015 Author Report Posted January 21, 2015 I believe it is a locking ring for the stud in the head. The stud is screwed in to a certain depth and the insert is slipped down on the stud and driven into a counter bored hole at the stud entrance to secure the stud from turning. The teeth on the stud engage the inner ring teeth and the outer ring teeth are driven into the aluminum head material. Obviously the outside nut was frozen to the threads and the mechanic applied Charles Atlas torque trying to break it free and succeeded in breaking free not the nut but the stud securing items. You may be faced with cylinder removal and head welding You are correct. The ring is the locking ring that was stripped due to excessive torque. The threads look OK the cylinder head side. See pic...
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