The crankshaft bolt is indeed at the front of the engine and yes, it's a tight fit. The nut is in addition "recessed" inside the crankshaft pulley so it's as hard to see as to get a wrench on it. It's a 27mm, I believe, and a deep socket on a 12 inch ratchet should fit. It's probably necessary to do the turning from under the car while someone up top watches for TDC.

If the PS pump belt slips, it is probably too loose and/or old/worn. Tightening and/or replacing the belt may help. A remote starter switch that allows you to "bump" the engine can also be used, carefully, to advance the engine one valve opening at a time. I have done that; it's a lot nicer than fighting with wrenches in tight places.

You measure cam chain stretch at the timing marks on the camshaft, at the front where the first bearing is.

Jeremy

__________________

"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970