I finally got tired from the grinding/chirping noise coming every morning from my engine due to the bad timing chain tensioner, and decided to replace it. Got a tensioner and the instruction on how to replace it, but it is quite confusing. I'm going through the supercharger removal. This manual covers multiple body types manual /engines, and mentions unscrewing the engine mounts and lifting the engine. I don't see a clear indication that this particular procedure does or does not apply to my engine, so can anyone confirm that? If I have to lift the engine to get the supercharger out, I'd need the equipment I don't have at the moment.

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2002 C230K

Ok, I went ahead, and replaced the thing over the weekend, the whole procedure was simpler than I had expected. The supercharger removal was easy and didn't require any lifting of the engine or anything like that, maybe some bolts were hard to reach with the torque wrench when I assembled it back. That's the good part. I drove the car yesterday for some time, everything seemed fine, and left it sitting overnight.
But here is the bad part: I started the car this morning, but the rattle was still there, and got noticeably WORSE! It used to rattle for a split second just after the engine is started, today it rattled all the time while the starter was cranking up the engine, plus about a second after that. What could go wrong? I checked yesterday, did not notice any oil leaks, or any signs that something went wrong. When I bought a new tensioner, it didn't come with a central piece (the bolt that goes in the middle of the tensioner and pushes the spring), and the little plastic insert that goes inside of the spring. I just didn't know about those. I reused the both parts from the old tensioner. The insert looked like it is was worn by one side. Could that be a problem?

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2002 C230K

It's hard to say what the problem is without hearing it for myself, but it sounds like the cam advance mechanism is at fault.

I made the recording of this sound. It is uploaded here. You can hear the rattle right after the engine is started, and it lasted for less than a second.
I tried to record a better one today, without a beeping coming out of the cabin, but it didn't rattle. I have a sloped driveway, and noticed that if my car is parked downhill, it doesn't rattle at all.

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2002 C230K

The warning beeper pretty much drowns out everything else, but I still think the cam advance mechanism is the culprit. MB issued a Technical Bulletin, P-B-05.20/13a, a few years ago which describes the problem you have. Before you go this route though, you might want to try removing the Poly V-belt and see if the problem goes away. The alternator on your car has an internal inertia clutch, which reduces the engine load during cranking. I've seen a few of these make noise over the years. It's rare, but it's worth eliminating this possibility before you spend anymore time and money.

Thanks for the alternator suggestion, I'll try it over the weekend. I've attempted to pinpoint the location of the sound - it comes from the top frontal part of the engine, so as you said, it is very unlikely that the alternator is the problem.
The rattle is re-recorded without the beeping.
How difficult is to replace the camshaft adjusters? I can only find the instruction on how to replace the camshafts in my manual. If I don't have to remove the camshafts, but just get to them by removing the valve cover and the front cover of the cylinder block I might go for it. I know that the camshafts must be locked by a special tool, any other special tools that I will need?
Can I see the adjusters if I just remove the valve cover and do the inspection?

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2002 C230K

It's not really a big deal, but you have to remember that even a small mistake can end up costing big bucks! The holding tool for the camshafts is #271-589-00-61-00. The tensioning rail can simply be pushed back to relieve the chain tension, so there's no need to remove the tensioner again. MB makes a tool for this too. It's part number is 271-589-00-31-00, but I'm sure there's an easy way to unload the chain without using this tool.

Like I said previously, it's not a hard job to do, but it's not a hard job to screw up either. For what it's worth, the MB Time Guide suggests a little less than four hours to do this job. You should consider the cost vs. risk, along with your own comfort level before you tackle this job.

Hm, something doesn't seem right here. My engine is 111.981. I went to the dealership to buy a new cam adjuster, and they brought be the adjuster solenoid magnet... not exactly what I expected to see. They said that this part is referred by technicians as a "camshaft adjuster".
They also checked the P-B-05.20/13a tsb, and it does not apply to the 111 engine, only 271.
The camshaft holding tool #271-589-00-61-00 also looks like for the 271 engine.
What do I need to replace? The magnet?

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2002 C230K