Ok I need to know if other people have this issue and is normal. I took my 2012 c63 amg to mercedes for a rattle I started noticing on start up. It only happens usually when oil is warm. Doesn't happen every time. But on initial start up there is a rattle lasting for a second or so then goes away. It's in region of driver side front valve cover. I have found info on this and videos of what sounds exactly like the same noise I'm experiencing. In all those posts and videos it ended up being noisy cam adjusters that were replaced. When I took it to mercedes they told me the sound is normal. I argued with them for a while and ended up talking to the tech who worked on my car. He was very knowledgeable and said all these motors make that sound and it's a delay in the build up of oil pressure he assured me it was fine. He said his amg makes the same noise. I would be fine with his explanation if I wasn't seeing these YouTube videos of my sound and hearing that it was fixed. What do you guys think is it normal?? Second opinion?? This tech seemed like he knew what he was talking about.

Sounds like they know what they are talking about. You've got the ole lifter noise, and it's fine. As long as it goes away after a short period of time as you mentioned.

I'm guessing those who have the adjusters replaced are either A) going to dealers that hear the noise and just replace them just because... or B) the noise never goes away and they need to replaced.

I've had 3 of the 4 cam adjusters replaced, and now am get the noise again (presumably from the 4th). I've been told that it's actually not doing any damage, just noisy. This was all warranty work.

Cam adjusters need to be replaced. They go bad after about 60,000km typically.

Yeah my car has only 25k miles on it. It seems a lot of people that have posted they had the cam adjusters replaced end up getting the noise again. Maybe it is like the tech said it's normal. I just want it fixed if it's not. Thinking about taking it to a different benz dealer and see what their service department says. Iv only had the car for 2 months so it could have been making the sound from the very beginning but just recently noticed.

How much do cam adjusters cost for this car with labor and all?

My engine has had the same noise last summer when the car was less than a year old. It was at the dealership for over a week while they sent recordings of the noise to Germany. Finally they replaced a cam adjuster. It never really made any difference. I still get the rattle on start up sometimes.

The lifters can rattle if they get wore out, I've seen that before, usually when the car is hot started it will clack.

Can adjusters can rattle on a cold or hot start. This can get very loud.

Ok an update. Took my car to another dealer for a second opinion. They said it was the camshaft adjusters like I thought. They are on order and getting replaced under warrenty. We will see if the noise goes away permanently hopefully it does.

I've read mixed reviews on whether or not replacing the cam adjusters is an actual fix for this problem. Has anyone found a solution yet? All the forum threads seems to run dry.

Today was the first day i've ever heard this infamous rattle on startup. Strangely this noise, for me, started a day after taking my car for a service. (My first service since i purchased the car)
When i took it for its service i also asked the guy to look into an occasional small oil leak that was dropping onto the exhaust (had only started a couple of weeks ago). Upon inspection he found the RHS rocker/valve cover had its bolts partially loosend and had one bolt missing entirely. So he replaced the missing bolt and tightend the other bolts as he suspected this was causing the oil leak. (Unfortunatley it's still got an oil leak so i suspect i need to change the gasket).

Day after, boom, cam rattle on startup. Im guessing the previous owner tried to "fix" the rattle by loosening the rocker cover bolts. Seems odd to me.

This thread is from 2015. Lots have been figured out since then. Its either lifters or adjusters.

Lifters lose tolerance after 70k miles as per INA. the metal walls of the lifter inside the bucket just thins out, it can’t be helped. Thick oil adds a thicker film to prevent bleed down but still depends on length of time car has been sitting. Oil is replenished to the heads again once oil pressure is at baseline psi and again it quiets down.

Adjusters can be tested easily by taking the valve covers off and checking if the cams freely float or actually remain securely locked in home base.

The reason for the mixed reviews is because everyone is a google expert and don’t follow the system of diagnosing, inspecting, and verifying function before they replace parts. Usually someone watches a YouTube video and uses that as the answer to their problems without trying to figure out what was actually wrong.

If you know the function of the valvetrain plenty, PLENTY, of owners have repaired and done their own work successfully and have had the pleasure of a noise free car. A small percentage of people try to look for answers elsewhere when the answer is in the cylinder heads right in front of them. Your problem isn’t in the forums but you can figure it out by hiring someone that knows what they’re doing to take a look (probably should be your only option considering).

They have aftermarket replacement and improved plates now for the adjusters that fix the issue entirely. Constant ticking vs start rattle and goes away are two different things, but common on these. One is worn adjuster plates and the other is potentially worn lifters.