rich1068

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?

CaliBenzDriver

I don't know about "chain rattling"... have a look here.

rich1068

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?

CaliBenzDriver

can you capture an MP3 sound clip??
With this description: thoughts are limp chain TENSIONER.

dan190

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)

rich1068

Apologies @CaliBenzDriver , away with the family last week and couldn't reply. And it appears @dan190 has nailed it.

Exactly like that! I'll have a look through your posts Dan but if you could expand on your clean up regime that would be great

dan190

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

rich1068

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.

rich1068

Recorded a short video.

dan190

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

rich1068

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.

rich1068

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...