M112 chain rattle?
Thread Starter
Junior Member
Joined: Jul 2023
Posts: 62
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W209 CLK 240
M112 chain rattle?
Hi all. Normally I'm over in the CLK section but I wanted to throw this a little wider.
I have a 2003 W209 CLK 240 with the 2.6 M112. I've owned it since May last year, two owner car and I picked it up with 79k miles and I've since put 6k miles on it. It's had 3 oil changes since I bought it (one on purchase, one after 6 months, one after 12 months) and each time I've used the correct MB oil and filter. Previous owner had it since 2006 and service history is a little patchy but he hardly did any miles. The last couple of years it barely moved.
Now, the issue. It's noisy. It wasn't when I first got it but it is now and I'm sure it's chain rattle. I can remove the drive belt to eliminate noises from the front and the rattle remains. Using a long screwdriver to my ear the noise seems internal. My question is should I get the chain looked at/replaced? I've read over and over that the M112/3 is bombproof but that it's not uncommon for this rattle to occur and the engine to perform exactly as it should for many thousands of miles. I've also read that if things got more serious and the chain were to be stretched I'd get plenty of warnings via dash lights and codes.
Am I worrying about nothing?
I have a 2003 W209 CLK 240 with the 2.6 M112. I've owned it since May last year, two owner car and I picked it up with 79k miles and I've since put 6k miles on it. It's had 3 oil changes since I bought it (one on purchase, one after 6 months, one after 12 months) and each time I've used the correct MB oil and filter. Previous owner had it since 2006 and service history is a little patchy but he hardly did any miles. The last couple of years it barely moved.
Now, the issue. It's noisy. It wasn't when I first got it but it is now and I'm sure it's chain rattle. I can remove the drive belt to eliminate noises from the front and the rattle remains. Using a long screwdriver to my ear the noise seems internal. My question is should I get the chain looked at/replaced? I've read over and over that the M112/3 is bombproof but that it's not uncommon for this rattle to occur and the engine to perform exactly as it should for many thousands of miles. I've also read that if things got more serious and the chain were to be stretched I'd get plenty of warnings via dash lights and codes.
Am I worrying about nothing?
Out Of Control!!
Joined: Apr 2019
Posts: 11,921
Likes: 6,769
From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
Hi all. Normally I'm over in the CLK section but I wanted to throw this a little wider.
I have a 2003 W209 CLK 240 with the 2.6 M112. I've owned it since May last year, two owner car and I picked it up with 79k miles and I've since put 6k miles on it. It's had 3 oil changes since I bought it (one on purchase, one after 6 months, one after 12 months) and each time I've used the correct MB oil and filter. Previous owner had it since 2006 and service history is a little patchy but he hardly did any miles. The last couple of years it barely moved.
Now, the issue. It's noisy. It wasn't when I first got it but it is now and I'm sure it's chain rattle. I can remove the drive belt to eliminate noises from the front and the rattle remains. Using a long screwdriver to my ear the noise seems internal. My question is should I get the chain looked at/replaced? I've read over and over that the M112/3 is bombproof but that it's not uncommon for this rattle to occur and the engine to perform exactly as it should for many thousands of miles. I've also read that if things got more serious and the chain were to be stretched I'd get plenty of warnings via dash lights and codes.
Am I worrying about nothing?
I have a 2003 W209 CLK 240 with the 2.6 M112. I've owned it since May last year, two owner car and I picked it up with 79k miles and I've since put 6k miles on it. It's had 3 oil changes since I bought it (one on purchase, one after 6 months, one after 12 months) and each time I've used the correct MB oil and filter. Previous owner had it since 2006 and service history is a little patchy but he hardly did any miles. The last couple of years it barely moved.
Now, the issue. It's noisy. It wasn't when I first got it but it is now and I'm sure it's chain rattle. I can remove the drive belt to eliminate noises from the front and the rattle remains. Using a long screwdriver to my ear the noise seems internal. My question is should I get the chain looked at/replaced? I've read over and over that the M112/3 is bombproof but that it's not uncommon for this rattle to occur and the engine to perform exactly as it should for many thousands of miles. I've also read that if things got more serious and the chain were to be stretched I'd get plenty of warnings via dash lights and codes.
Am I worrying about nothing?
Thread Starter
Junior Member
Joined: Jul 2023
Posts: 62
Likes: 17
W209 CLK 240
I don't know about "chain rattling"... have a look here.
Any more thoughts?
Out Of Control!!
Joined: Apr 2019
Posts: 11,921
Likes: 6,769
From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
Thanks for your reply but the noise mine makes is not like that.
Mine is a rhythmic rattle at idle which goes away as the revs rise.
It also does it regardless of the engine being hot or cold. Less pronounced when it's cold as obviously the idle is a little higher.
Any more thoughts?
Mine is a rhythmic rattle at idle which goes away as the revs rise.
It also does it regardless of the engine being hot or cold. Less pronounced when it's cold as obviously the idle is a little higher.
Any more thoughts?
With this description: thoughts are limp chain TENSIONER.
Junior Member
Joined: Oct 2012
Posts: 35
Likes: 5
From: Moldova
89 190E + 99 C240 + 00 CL500
hey rich1068, does it sound similar to this ? https://player.vimeo.com/video/996863708
if so, its the lifters, I went through hell trying to figure this one out, but in the end a cleanup of the oil system (3 times lol) did the trick, problem with old cars, esp if they havent been maintained is the sludge that gets everywhere obstructing normal oil flow and lifters go first (technically a good thing since its an early warning + an easy fix)
if so, its the lifters, I went through hell trying to figure this one out, but in the end a cleanup of the oil system (3 times lol) did the trick, problem with old cars, esp if they havent been maintained is the sludge that gets everywhere obstructing normal oil flow and lifters go first (technically a good thing since its an early warning + an easy fix)
Thread Starter
Junior Member
Joined: Jul 2023
Posts: 62
Likes: 17
W209 CLK 240
hey rich1068, does it sound similar to this ? https://player.vimeo.com/video/996863708
if so, its the lifters, I went through hell trying to figure this one out, but in the end a cleanup of the oil system (3 times lol) did the trick, problem with old cars, esp if they havent been maintained is the sludge that gets everywhere obstructing normal oil flow and lifters go first (technically a good thing since its an early warning + an easy fix)
if so, its the lifters, I went through hell trying to figure this one out, but in the end a cleanup of the oil system (3 times lol) did the trick, problem with old cars, esp if they havent been maintained is the sludge that gets everywhere obstructing normal oil flow and lifters go first (technically a good thing since its an early warning + an easy fix)
Junior Member
Joined: Oct 2012
Posts: 35
Likes: 5
From: Moldova
89 190E + 99 C240 + 00 CL500
hey @rich1068 oh nice we can tag, didnt know that )
ya, I started just like you thinking it was the chain ) I even tested the chain, see thread over here: https://www.benzworld.org/threads/ne...ng-top.3130777 (posted here too, but the thread didnt pick up
)
I also have a secondary noise, its the crank balancer, you can hear it in post 40, basically go through the entire thread, worth it
ya, I started just like you thinking it was the chain ) I even tested the chain, see thread over here: https://www.benzworld.org/threads/ne...ng-top.3130777 (posted here too, but the thread didnt pick up
)I also have a secondary noise, its the crank balancer, you can hear it in post 40, basically go through the entire thread, worth it
Last edited by dan190; Aug 12, 2024 at 06:10 AM.
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Thread Starter
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Joined: Jul 2023
Posts: 62
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W209 CLK 240
Much appreciated Dan.
Would you suggest a couple of flushes before anything else? I did use some Wynn's Engine Flush on the last oil change a month or so ago which made no difference to the noise but I'm not too sure how good that product is.
Would you suggest a couple of flushes before anything else? I did use some Wynn's Engine Flush on the last oil change a month or so ago which made no difference to the noise but I'm not too sure how good that product is.
Last edited by rich1068; Aug 12, 2024 at 10:32 AM.
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Junior Member
Joined: Oct 2012
Posts: 35
Likes: 5
From: Moldova
89 190E + 99 C240 + 00 CL500
hey @rich1068 yours is not nearly as bad as mine, but can you rev it slowly while filming ? mine had a clear difference on rev, the balancer noise would subside and the ticks would get faster pointing clearly towards the lifters
I flushed it at least 3 times, but again mine was much worse
I flushed it at least 3 times, but again mine was much worse
Thread Starter
Junior Member
Joined: Jul 2023
Posts: 62
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W209 CLK 240
I'll try and get another video.
Since posting a few days ago I have picked up some Liqui Moly Hydraulic Lifter Additive and poured that in. I've covered less than 100 miles since so the jury is still out but I thought it was worth a punt. We'll see.
Since posting a few days ago I have picked up some Liqui Moly Hydraulic Lifter Additive and poured that in. I've covered less than 100 miles since so the jury is still out but I thought it was worth a punt. We'll see.
Thread Starter
Junior Member
Joined: Jul 2023
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W209 CLK 240
Just to update, the Liqui Moly made no difference and I'm chasing my tail with this one so I've booked it in at a local MB authorised garage for an hour of investigation. There are guys there who worked on these when they were new so they will either reassure me or scare me to death...
Thread Starter
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W209 CLK 240
Slightly disappointing outcome. They can hear it but don't know what it is
On the upside they affirmed the consensus that these M112 engines are pretty much bombproof and that it's unlikely to go pop anytime soon. Their advice? Don't worry about it.
On the upside they affirmed the consensus that these M112 engines are pretty much bombproof and that it's unlikely to go pop anytime soon. Their advice? Don't worry about it.
Junior Member
Joined: Oct 2012
Posts: 35
Likes: 5
From: Moldova
89 190E + 99 C240 + 00 CL500
hey @rich1068 thing is yours is more about the harmonic balancer or another pulley, know how to test ? remove the belt, let it run for a minute without the access belt, it wont hurt it, but you can tell which pulley this way
engines are sturdy indeed, but not if the chain goes or the balancer comes apart which they do as they are half rubber/half metal, I had this happen on my older m103, while driving, tell ya its a scary feeling
harmonic balancer is cheap enough if something https://spareto.com/oe/1120351300
engines are sturdy indeed, but not if the chain goes or the balancer comes apart
which they do as they are half rubber/half metal, I had this happen on my older m103, while driving, tell ya its a scary feelingharmonic balancer is cheap enough if something https://spareto.com/oe/1120351300
Thread Starter
Junior Member
Joined: Jul 2023
Posts: 62
Likes: 17
W209 CLK 240
hey @rich1068 thing is yours is more about the harmonic balancer or another pulley, know how to test ? remove the belt, let it run for a minute without the access belt, it wont hurt it, but you can tell which pulley this way
