I have a 603 (87 300SDL) engine w/275K-mi that had a vacuum pump failure. I have the valve cover off, vacuum pump out, pulled the side cover on the oil pan and am in the process of removing the oil pan to clean it out. The way it looks now, the timing chain and sprockets are undamaged, no scuffing or gouges, no damage to the face cam on the IP which drives the vacuum pump. The balls from the vac pump bearing went into the pan along with part of the pump casting, there are some particles in the pan, so there was some grinding of pump pieces.

The timing chain apparently skipped a tooth or two, because the car emitted a lot of black smoke when it failed and the timing chain cracked thru the valve cover, although it remained in one piece; I assume that a piece lodged in the chain as it went over the top sprocket, pushed it up and broke through the cover. There is no debris in the camshaft area, around the cam sprocket or in the valve cover.

My plan is to replace the vacuum pump and cam chain.

I guess I have two questions -
1 - Am I pretty safe doing that as long as I don't see any further damage and I clean everything out as best I can?
2 - injection timing - I've searched the method of adjusting the start of injection and it seems to rely on knowing that the cam, crank and IP are in approximately the right position before you actually set the IP position. I know there are marks on the cam and crank, is there a similar mark on the IP sprocket to tell you where to make the initial setting?

Thanks