Brett, While I'm waiting for my family to arrive for Thanksgiving dinner, I would like to give you some information on timing chain replacement. I have searched my MB manuals back to the 50's(180D and 190Db)and no where have I found any specific specs. about when to replace the timing chain. Let me quote what the manual states:"If the timing requires correction,install an offset Woodruff key,or if the chain is excessively elongated,install a new timing chain." They are talking about the key in the camshaft, and are available in steps of 4 to
10 degrees offset measured at the crankshaft. If your chain tensioner is good and the sliding rail is in good shape,there will be no slack in the chain. With wear the chain will seem to get longer causing valve timing to be altered. Too much change in valve timing will cause the pistons to hit the valves,and something has to give and it is usually the chain.
Check the tensioner and if it is good and your chain is tight,install one of the offset keys.You will save a bundle of money and can be assured that your chain will last for many more thousands of miles. When a chain breaks it is most likely caused by some other part breaking,causing the chain to try and jump a tooth. Since there is no room to do so the chain will snap.
Good luck
Bill Lewallen Lexington,Ky.