Howard_Woodard

Adjuster Issue

It's a 2011 Mercedes E-63 W212 M156 with 88,000 miles on it and has a serial number that indicates that it was built after most of the initial "watchouts" had been rectified by Mercedes. It rarely gets driven any more, and when it does, it's only for 30-50 miles at a time to get it warm, let all the lubricants get distributed, and charge the little auxiliary battery. ...and, of course, to refresh my awareness of how sweet it is to drive it. I tell you this so that the timeframe can be understood a little better. It sounds like the problem arose over a fairly extended period of time but if it had been driven regularly it would have happened in about a week.

A couple of months ago, I noticed that when I started it, the engine didn't seem as crisp as usual. In fact, at about 1200-1400 [unloaded] RPM there was a little vibration -- made me think of what a slight miss feels like. Above that RPM, or when driving it, I didn't notice the vibration. I think on that drive I also might have first noticed a slight hesitation on acceleration, but only slight, and I rationalized that it just needed to be "limbered up".

When a relative from out of town came to visit, I let them use the car while they were here. I was standing next to it when they first started it and noticed some sort of momentary racket, like when you were a kid and would put trading cards in the spokes of your bike, that racket -- or that time you left a wrench on top of the radiator before starting the car. But it went away almost instantly. However, over the week they were here, the acceleration hesitation became more of a stumble/delay and the start-up racket got louder, really louder, though it would go completely away in about 2 seconds or less after starting and not recur until it had sat for a while -- like hydraulic lifters when they fail and start leaking down between use.

By this time, I'm starting to google the issue and it has become pretty evident that the start-up racket is most likely worn locking plates and pins in the cam adjusters. Other than those darned back, bottom, valve cover bolts, and the need for a tool to lock the two camshafts into place, it looks like a doable DIY job.

But here's the question that I'd like to understand the potential answers to, so that I don't do the work and button it back up, only to find there was something else that I should have taken care of while in there.

All the posts and related YouTube videos that I've found speak only of the noise, nothing about performance. In my case, the performance issues are as noticeable as the ugly banging, start-up sound, even though it has not thrown any OBDII codes. I know that timing issues can cause symptoms like missing and stumbling, but I'm assuming that since this is an interference engine, the CVT range is limited, but would still be enough to cause performance issues.

Do any of you know of a case where an M156 was having performance issues like I’ve described that was fixed by replacing only the cam adjusters?

Thanks if you stuck with me through that long description, and thanks in advance for whatever help you can offer.

Howard

6_Myles

Once you get the tools, the adjuster is a very DIY job. If you are anywhere near Western North Carolina, you are welcome to use mine.

Be sure to check the cam lobes and bucket wear while you have the valve cover off. If you haven't already, you may want to look at replacing the injectors as a preventative maintenance item (Coils and spark plugs sometime soon too). Also double check the vacuum lines to see if you have any cracks/broken lines,

If you aren't getting any trouble codes, shouldn't be anything other than the adjusters. But they only rattle at startup and don't really affect performance after that....unless they are REALLY worn out, which isn't gonna happen at 88k miles.

Howard_Woodard

I thought that I had replied to this, but I see that I didn't. I apologize for not closing the thread out and your offer of help/tools was much appreciated though Seattle is a bit far away from NC for that.

It turns out that I had two problems. One was, in fact, the cam adjustors and replacing them eliminated the ugly startup noise. The second was that the motor mounts under that big ol' V-8 were completely shot and, besides sitting unsecured on the frame, it was moving around quite a bit based on torque demand. Replacing them got rid of the random stumbles and delays on quick/rapid acceleration.

The car is now back to being the well-behaved beast it was before all this started.

Thanks for your help.

Howard

Pierregirard

From what I've seen, those cam adjusters in your M156 engine are pretty important. They control when the camshafts and valves move, which is a big deal for how the engine runs. So, if they start wearing out or giving trouble, it's not just weird noises you might hear when you start up. It could mess with the engine's timing, causing issues like the ones you've mentioned: hesitation, stumbling, and a shaky idle. Basically, if the timing's off, your engine might not run as smoothly or as powerfully as it should.

Howard_Woodard

That's what my original thinking was but I haven't the experience to know for sure, and the few responses I got said they weren't aware of them being the cause of my performance symptoms, so I just assumed that any other improvement, besides the noise elimination, would be the result of the other work that I did. Ha ha, heck, I even made up a good theory of how the motor moving around could affect certain sensors and cause problems with the electronic throttle.

Thanks for your post.

Howard