Guys - uh - first, let's clear up something. The top quarter inch of that page got chopped off with one teeny tiny detail. All those numbers are AT 2mm VALVE LIFT. You should measure nine degrees at 2mm intake life, which means ZERO degrees stretch. Measuring eleven indicates TWO degrees stretch, which is acceptable according to specs.
Now assuming that's clear, you're saying that a chain stretched 3-10 degrees should be adjusted for with an offset key, rather than replaced? Hmmm. An interesting side note: I found something that may indicate a typo in the manual. The EPC describes the four keys as 2, 3, 4, and 5 degree offsets. The manual says 4, 6, 8, and 10 "crankshaft". It also shows a 1.3mm offset for "ten" degrees. It then says one tooth equal 18 degrees. So if 10 degrees is 1.3mm, 18 degrees would be roughly 2.5mm. Now, from memory, I recall the tooth spacing being more than ~2.5mm apart on the cam sprocket...! I wonder if the EPC is correct and the manual is wrong? Or am I just really confused?
Personally I'd roll in a new chain, and use the offset keys only if needed with the new chain. But that's just me. On my 603 engine, a new chain put the timing marks back EXACTLY on spec, zero stretch. Maybe the older timing design had sloppy tolerances? I dunno. Remember the IP timing must be adjusted after you get the crank & cam timed properly.
Finally, my experience is 99% based on OM60x engines. For those, there are NO offset keys, period. The factory manunal & TSB explicitly state that at 4 degrees or more of elongation, the chain is to be replaced. If the elongation is 10 degrees or more, a borescope is required to check the pistons and valves for damage. So on newer engines, MB decided the old procedure was not acceptable. But it seems that on older engines, perhaps you can run the same chain with offset keys until it breaks (either the chain or the engine
).
Regards,