1. Yes you can replace the chain without replacing the guides, but if you're gonna go that deep, makes no sense not to. you can replace two out of the three guides assuming the front timing cover is not removed.
2. Again, since you'll be elbow deep in the engine, for peace of mind you might as well do the water pump and t-stat too...the coolant has to be drained anyway. Don't forget the chain tensioner
3. Yes
4. I have no idea, I DIYed mine. Maybe someone will chip in on this...
5. Anybody?
6. Take your time, do lots of research. An assistant will be very helpful. I did mine at around 121k, solo, took two days. I suspended the old and new chain on a thin nail next to each other, the old chain was stretched only about 2mm. I seriously believe that with regular maintenance and good quality oil the M271 chain should last a long time. Then again they have been known to fail under 50k...ymmv
7. Good luck

 

I suggest that you first ask your independent.

I know that it's "possible" to replace the timing chain without removing the PITA alternator and timing-chain slack-adjuster. But, in that case, I do not know how hard it really is to pull the timing chain tight, then add the link. It may be easy. My guess is that maybe using wire to connect the two halves, and then slowly tightening the wire, is how the two ends of the timing chain come together. And, maybe a long screwdriver to carefully push the slack-adjuster back in.

So, unless a mechanic has done that before, they are likely looking at spending some time figuring out how to successfully do that. Or, imho, if I was the mechanic, I'd say it wasn't worth the time or risk, and just remove the alternator. Unless the mechanic does a number of this type of job, it's cheaper and better for the customer to remove the alternator.


It's not hard to replace the timing chain, *if* the chain is not broken and the gears are still fine. That's most likely the case, if the timing chain hasn't broken.
You can get the IWIS chain at a low cost. I got both (IWIS and MB direct from a Dealer). I very often my the same part from different manufacture's to see the differences. But, knowledge-wise, that also helps me professionally (engineer) to see what company's do to make better products, or (more often) to make cheaper products.

There are a few good threads on how to do the replacement.

A thing that I will mention, is to use a proper timing chain link tool!
Otherwise, the pin will be too loose, too tight, bent, not splayed enough, splayed too much, overly stressed, under stressed, etc, etc, etc.
Will "it work" without the proper tool? Well, will someone die if they eat 15 pounds of dirt?? Maybe not. It may not have any effect. Or, there may be longer term effects (stomach, GI system) that don't show up for a while (like smoking and lung cancer, or drinking to excess and liver disease).

I bought a kit from ebay for ~$95.
It allows for the pin removal and installation.

My timing chain guides had very little wear (85K miles). Still, I replaced them.
My Mustang is ~30 years old, and going strong. My '05 C230K is a baby compared to my Mustang. I plan on keeping both for a very very long time. Other cars will come and go. Those are my 2 toys.
So, I'm not taking the cheap, or short-term, approach to any work on my C230.

 

Thanks for the insights and the humor.

Like RedGray I keep my cars a long time. (I would probably still have my 1990 Miata if trees hadn't fallen on it in a tropical storm. The C230 replaced a 96 Infiniti G20 that I owned for over 21 years.)

So I am taking the long view. Although I'm planning on a minimum of 5 years, it is conceivable that the C230 will be with me another ten. It is almost certain that the timing chain will fail in 5-10 years when the car will have between 175,000 and 200,000 miles. (But just like I am not planning to eat 15 pounds of dirt to assess the health risks I don't think I will push my luck and find out exactly when it will fail.) If I have the chain replaced now, I should not have to consider doing it again for at least 70,000 miles.

I'm planning to talk to my mechanic and see what he will charge. If I'm not going to save a huge amount of money, I may have him do it and save my time and energy for some of the other projects on my list. He works on all makes, but have seen quite a few Mercedes at his shop including his personal E Class AMG. So I think he has the skill. He has told me that he has the chain tool.

 

Just get it done. And this is from the guy who DIY's almost, everything.