The vacuum gizmo is the egr controller, you can discard it since you
don't have one. There will also be an EGR valve on the intake manifold.
The pipe going into the oil pan is the drain from the oil separator in
the air filter housing, all W123 diesels have one.
Likely the rebuilder put WAY too much clearance on the valve guides,
unless familiar with Benz practice. Easy way to check is to pull the
cam and remove a couple valve springs. If the valve will preceptibly
move sidways when lowered down off the seat, there is too much
clearance.
The other likely problem is way too much piston clearance, and that you
can only check by taking them out. Should be 0.001", very tight. You
can check for wear by pulling the head (as I'm sure you will be doing).
Unless run out of oil until the engine seized, likely the crank and
rods are fine, they don't cause problems in that engine. Pistons may
be shot, too, if there was excessive clearance, it causes the rings to
flex sideways and extrudes the ring lands.
Peter
