HI, 420SEL with 146K; runs perfectly. I am about to at minimum inspect/change the upper guide rails; should I consider removing the front cover and replacing all of them? What about the oil pump chain and guide rail? I would hate to see an engine wreck on a car this nice (and an engine this expensive to repair).
Also, interested in hearing from people who have done this: pitfalls, shortcuts, misc. advice. Thanks

 

IMHO, if you are going to open up the engine, and with 146K miles and all you mentioned are the original parts from when the car was new, I would replace everything you mentioned plus the timing chain, Why replace the guid rails only? and not the timing chain/belt? Unless I miss something in your post? In the shop manual for my 450SLC it state when replacing the timing chain the guide rails should also be replaced as standard practice, or vice versa ( my opionion on guide rails) Are you experience in this type of work, have the special toos required? If not go to a dealer or a good private shop. Personally I wouldn't tackle a job like you propose and I have been DIY and restoration for 40 years. Please correct if I am wrong about what guide rails you are talking about. Might as well replace the water pump as that has to come off. Again standard practice, unless it is new?