pop valve popped out

The engine in 911SC backfired this morning while starting. From that point on it would not start period. Opened up the air box and found the pop valve assembly no longer attached to the air box. What happened?

The same thing happened to me just after I installed it (and waited a day for the glue to dry). The trouble was that the valve itself is made from some high-impact plastic taht is quite smooth and shiny. Almost greasy looking. Too smooth for the epoxy to grip. You can tell if this is what heppened because all the dry glue will be stuck to the air box, and not to the popoff valve.

To fix, you chip off the dry glue (stuff a rag in the air box so the glue chips don't go into the engine). Go over BOTH mating surfaces (the inside of the hole in the air box as well as the outside of the popoff valve) with sandpaper. Then reglue. Using good, high temperature epoxy glue. Be sure the popoff valve hinge is nearest to the rear bumper.

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'83 SC