[Walt Fricke]

Vinny nailed it, as you found when you pulled the chain covers and looked.

Just reassembling the parts in the tensioner will not work well. I did just that (I had dislodged the cap by ham handed prying for other purposes), but after a year or so on a track car it popped out. The cap part is just held in with the pressure from the three or whatnot bottom pieces. Since they came out, they have lost some of their tension, or perhaps the original sharpness of their edges.

Subsequently, I used a Dremel with a suitable bit to cut a groove inside the hole in the tensioner, so the ends of the cap could be spread out a bit more and had something to grip. This has held, though I haven't used the engine it is in much since then.

I am not surprised that these parts caused no damage. Elephant feet, or the nuts securing the elephant foot adjuster, from time to time get free and end up harmlessly in the sump. Not that one would be caviler about loose parts inside the engine, of course.