M112 Engine Knocking Sound
My 2005 CLK 320 with the M112 engine started giving a knocking/lifter sound some time ago from the driver side of the engine. It basically happens when I come to a complete stop in D while my foot is on the brakes. As the engine idles, I can hear the sound. If I put the car in N, the sound goes away.
It's definitely not the purge valve as I know that sound. It's more of a metal sound.
So I left the car in D, applied the E-brake all the way, and got out of the car and recorded the sound so you can hear it. It can be downloaded from my dropbox here: https://www.dropbox.com/s/z51ia7g04w...Sound.mp3?dl=0
I did a scan with SDS and the only code listed was P2062 - Fault is stored in component N15/3 (ETC [EGS] control unit).(P0743)
Appreciate the feedback and thank you in advance.
Last edited by xsever; Aug 11, 2017 at 02:16 AM.
We had stopped using the Fuchs Titan SuperSyn 229.5 5W-40 because it was not lasting more than 5,000 km here in Lebanon yet it costs twice the price as the Rottweil oil we've used for the last 2 oil changes.
I think I'm going to go back to the Fuchs SuperSyn next time and see if the noise is gone.
I spoke about oil change intervals in Lebanon for MB before in this thread and how the 229.5 oils were not lasting the 13,000 miles they are supposed to last.
https://mbworld.org/forums/clk-class...-interval.html
Now I'm wondering if I should be worried

xsever, keep me posted on what you find. And of course, Rudeney, your input is immensely appreciated, if there's anything else you can think of
Now I'm wondering if I should be worried

xsever, keep me posted on what you find. And of course, Rudeney, your input is immensely appreciated, if there's anything else you can think of

What engine oil and filter are you using and how often are you doing oil changes?
I change the oil & oil filter every 10,000 miles. I'm coming up on another 10k next week or two, so I'll be changing it then. Maybe we can see what happens after a fresh oil change.
One thing maybe I should mention. I got a popup on my display asking to top-up my oil a few months go. Something along the lines of "Add 1 quart of oil on next refuel" or something. I used the display to show me the more precise measurement, and I had somehow burned through almost 3 quarts of oil - this was about 5 months after the oil change. Of course, I added some more oil. When I conduct the full-service oil change, I add 8.5 quarts of Mobil1 0W-40.
Lastly, I occasionally get a check engine light for the purge control valve. It appeared on-and-off for about 2 weeks, but it has disappeared since
Last edited by zip439; Aug 12, 2016 at 07:52 AM. Reason: spelling
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I'll keep you all posted as to how this develops. The car has been driven for 2,500 km since the last oil change with 2,500 km to go.
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Yesterday was the first time where the engine had burned 1L of oil after 6,000 km on it.
After putting the new oil in, the lifters noise is still there, but it's too early to tell.
I will be reporting back on the noise as I put more kilometers on the car using the new oil.
i have the same problem. My car is s211 320 m112 112.949
This ticking sound i hear also in cabin when i accelarate. But not in n or p. Only under load.
I have changed all valve lifters, new oil Motul 5w40, new chain, chain tensioner.
But this ticking is always there. I have read many posts about this problem. Many people have this but nobody knows what it is...
I dont know what i have to do next..
It can be a problem with broken piston rings or main bearing.
...i think ...
in this post is same problem:
https://mbworld.org/forums/c-class-w...ml#post6169970
or here:
https://mbworld.org/forums/c-class-w...e-reverse.html
https://mbworld.org/forums/c-class-w...nop-noise.html
Here are some youtube videos of this knocking on m112:
This one is interesting scored cylinder walls:
I think it is a common problem with m112 with this knocking.
It is something with main bearing or pistons, piston rings or wrist pin or Rod knock.
I read many threads and post about it and people with this problem drive long time without destruction engine.
Best fix is a new used engine, repairing is too expensive.
Last edited by s211_320; Oct 17, 2016 at 03:41 AM.
I change the oil & oil filter every 10,000 miles. I'm coming up on another 10k next week or two, so I'll be changing it then. Maybe we can see what happens after a fresh oil change.
One thing maybe I should mention. I got a popup on my display asking to top-up my oil a few months go. Something along the lines of "Add 1 quart of oil on next refuel" or something. I used the display to show me the more precise measurement, and I had somehow burned through almost 3 quarts of oil - this was about 5 months after the oil change. Of course, I added some more oil. When I conduct the full-service oil change, I add 8.5 quarts of Mobil1 0W-40.
Lastly, I occasionally get a check engine light for the purge control valve. It appeared on-and-off for about 2 weeks, but it has disappeared since

My mechanic is advising me to leave it as is since it won't cause any damage and never leave me stranded. He said just live with the noise since I'm planning on changing cars next year or so.
Any updates from you?




I don't think this engine is underserviced. Again, try a light 5w-30 over winter.... The crankcase flushing can help, you did the right thing there. With the consumption, a fawlty PVC or vacuum hose can suck oil vapour into the air instead of the crankcase...etc etc. A test of spraying brake cleaner around the running engine might diagnose that.
One of the best products to use for your engine is 2-cycle oil in the gas at 500:1. I buy it by the gallon at walmart for $9 or so. TCW-3 spec is ashless, it has all the same kind of additives in regular gas, boosted with the high quality top oil. Marvel Mystery oil works in gas similarly, and the Stoddard solvent cleans out varnish, gums etc. I forgot to mention it as a remedy in your oil too, add a litre to your oil for the last 1000 miles....drain and use the MaxLife 5w-30 or GTX....or Mobil Clean if you get that.
I don't have much to add at this moment. There are MANY circulating and reciprocating parts under the hood. Maybe a belt or pulley decided to get loud, not much way to tell the difference between parts.
Try the stuff I said. until you do youll wonder if you have a mechanical problem or not.
If the noise is coming from the area you posted it is most likely a lifter then as that is really the only thing that could be making any sort of rattles at the top of the engine. Have you tried running an engine flush ? Usually you pour a bottle of the stuff in the oil and let it run for 10-15 minutes and then drain. The knocking noise will have nothing to do with your oil so just use whatever you are most happy with. Especially since your noise is only there at idle and warm this is a typical sign of lifter issue because rod and piston issues show themselves all the time regardless of temperature. Try an engine flush first see if it helps the noise. Other then that you can either ignore the issue or remove the lifters. I have a BMW with exactly this kind of crappy problem, It's been over 10 years and it's still doing it and hasn't done any damage. It's up to you though what you feel comfortable with your car.
If the noise is coming from the area you posted it is most likely a lifter then as that is really the only thing that could be making any sort of rattles at the top of the engine. Have you tried running an engine flush ? Usually you pour a bottle of the stuff in the oil and let it run for 10-15 minutes and then drain. The knocking noise will have nothing to do with your oil so just use whatever you are most happy with. Especially since your noise is only there at idle and warm this is a typical sign of lifter issue because rod and piston issues show themselves all the time regardless of temperature. Try an engine flush first see if it helps the noise. Other then that you can either ignore the issue or remove the lifters. I have a BMW with exactly this kind of crappy problem, It's been over 10 years and it's still doing it and hasn't done any damage. It's up to you though what you feel comfortable with your car.
In all cases, I bought a bottle of Motor Medic MF3 5-Minute Motor Flush to try it before my next oil change. It cost me $10 so why not. If this does not work, I'll try either Seafoam or Marvel Mystery Oil next and if both don't work, I'll just forget it and keep driving it like this until I sell it. The noise has not affected the performance at all. The car still does 27 mpg (8.7L/100km) on the highway doing 108 km/h.
Since my last post, I have shown it to a more seasoned mechanic who deals with M112 engines on a regular basis and he told me that the problem is probably in the chain and to leave it alone since this is a common yet harmless issue with these engines. He said to just try the flushes and if they don't work, to leave it alone.
In all cases, I bought a bottle of Motor Medic MF3 5-Minute Motor Flush to try it before my next oil change. It cost me $10 so why not. If this does not work, I'll try either Seafoam or Marvel Mystery Oil next and if both don't work, I'll just forget it and keep driving it like this until I sell it. The noise has not affected the performance at all. The car still does 27 mpg (8.7L/100km) on the highway doing 108 km/h.
Since my last post, I have shown it to a more seasoned mechanic who deals with M112 engines on a regular basis and he told me that the problem is probably in the chain and to leave it alone since this is a common yet harmless issue with these engines. He said to just try the flushes and if they don't work, to leave it alone.
these cars are just not worth throwing money at. Even if keeping for a long time its better to let the engine explode and get a used one and swap it then spending thousands on it and still having it expload lol
Audio file: https://drive.google.com/file/d/17Lx...w?usp=drivesdk
- Pour into the existing oil and let it idle for 10 minutes.
- Drain the old oil and replace it with new oil+filter.
- Add to the new oil and drive and see what happens.





