sheared cam cap bolt

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#11

07-29-2011, 03:24 PM

Lutz

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Join Date: Jan 2011

Location: North Shore of Lake Superior

Posts: 419

Quote:

Originally Posted by durielk

Well more to the story, first off I am an idiot. I did not check the replacement bolt, going on the assumtion that the auto parts gave me the right threads... wrong. The replacement bolt must be seized in there, I am going to try to get it out this morning.

At this point, I figure there is a 50-50 chance the threads are trashed. Should I bore to the next size & tap or go helix coil? That bolt is the one with the rear right locating pin, which may be a problem.

If I need to go much bigger, I am thinking on taking the head back off & to a machine shop as the locating pin may need to be enlarged, alternatives to that:
Leave it out.
Enlarge the pin & bolt cutouts for it, have the machine shop make a new larger pin.
Have the machine shop install a small pin somewhere else not on the bolt, but since the cam does not have any "bearing or enclosing race", if the pin is off the bearing is out of alignment.

thanks

I wouldn't jump to the conclusion that it was the wrong thread pitch, if it was, you very likely would have noticed it when starting the bolt with your fingers.

To me, this sounds even more like a too-long bolt. If that bolt broke off due to bottoming in the whole, the threaded portion left in the head is going to be very tight - an overtightened set screw essentially. Possibly enough to damage the threads, but possibly not.

Dave R. has some good tips on getting it out, and repairing it if the threads are ruined in the process.

There are a number of thread repair options out there, like heli-coil or keensert, but if need to go that route go back to the original thread size and depth.