here is my video link.

20140402 194428 - YouTube

at the end of the video you will hear a rumbly rythm - thats the noise and its very different than what you hear in this video. The video almost makes the engine sound like a diesel but I assure you the engine has the classic sewing machine sound of MB - except this stupid noise at idle - and its heard quite loud at the front lifting ear.



I am dreading this job and as Im a DIY all jobs person I will have to do this sometime. the car has 166,000 miles on it, fleece filter oil changes every 10,000 miles under my ownership. 2 oil changes yet.

I just develope a noise on my m104. I found clutch fan wobbles from side to side. I will take off fan belt and start it to see if noise is gone.Then rotate by hand all pulleys and acessories

What ever it is it sounds bloody dreadful.

Im being told its the timing chain and its slider rails, To remove the timing chain sliders on this engine one has to remove both cylinder heads as the rails are half buried in the cam sprocket cavity.

In the "ye olde" engines the upper timing case piece was a leaky ordeal with the U shaped rubber gasket so MB fixed that. They cast the head in a way that it has the upper timing case cast into the head - no separate seal and no leaks.

Its wonderful on the assembly line except that its a right pain to service for the mechanics working on it.

The easiest way (that Im told) is to yank the engine with trans out of the car and then do the timing chain job.

At the moment there are 2 cars sort of half n half in my home - one is a toyota camry with half engine missing and the other is a ford crown victoria whose front end needs a full replacement.

Dang. That sounds about right considering how awful that noise is. Good luck on the repair. ;)

Hi, any update on the issue?
I am very curios what was the source of the noise and its fix.

Okay thats the V six and some of those have the camshaft balancer issues, right? There was a lawsuit and some damages on some models. No expereince other than a little reading which warned me off the v six as applied to some years..Pretty sure its in the head not far from your location as described..the notes say its a cheap fix if done preventively and very costly if it fails..

those engines are the 3.5 liter DOHC head with VVT, aka the M272. This is the more luddite version of that its the 3.2 liter M112.. its a simple SOHC design and it has no reported balancer gear failure even after intergalactic mileage.

Its been 20,000 miles since this video and in about another half year or so Im going to pull the drivetrain out and do this job (free time).



Those M272 are so finicky you cannot even undo the valve covers without prepping it as they are also doing the job of the camshaft bearing caps.

Thanks for the response Zulfiqar..yer way ahead of me on that point. Good luck. Your engine is likely the better option..the m272 sounds overdesigned and pretty fragile..although the performance is pretty phenomenal..

i believe you can replace the chain only. It is quite simple, as it seems in the video. Just remove the left valve cover, cut the chain, link the new one to it and turn the engine by hand.
https://www.youtube.com/watch?v=fJmh7D9QsEU&t=166s

Needless to say, you should pay attention and not miss any link/tooth as timing would go off. See the two guides made out of steel sheet.

I am planning to do that next year probably. You could try it too. At least it is a lot less work. You don't have anything to loose.

The guides also wear out and will cause even a new chain to be loose. I have seen that in mazda and nissans.

Best to replace all those parts all at once.

I get your point on guide rails, but if you would do this and rattling stops then it should be fine i guess, until it starts rattling again.
At least you can do it in 2-3 hours of work, preparation/wrap-up included.

What is the current mileage on your car?
Mine it is only 110k but i can hear a small rattle on the right side of the engine, valve cover. (when looking from it from the front)
Will try the tensioner and then a chain swap.
Taking the whole engine apart only for timing at only 110k, i would rather let it blow up and deal with it then.
I doubt that it will break anytime soon.

I am only hearing the noise when idle. As soon as i rev it up a bit any rattling disappears. Maybe due to increase oil pressure or chain lack of oscillation under load or at different rpm.

Also, it could be the oil-pump spring tensioner but then it won't be quiet when revved.

Zulfiqar, replace the timing chain tensioner and see if that eliminates the noise. As you know the timing chain tensioner relies on the spring tension when the engine first starts, then oil pressure keeps the chain tight. I had a 1992 300CE that was noisy on cold starts. Replacing the timing chain tensioner resolved the problem.

I made some further investigation on my engine using a stethoscope.
The noise is heard mostly in the middle, at the airpump support and under it.
It's clearly the chain.
No noise coming from the valve covers/ heads, oil-pump zone and of course other belt driver accessories, as i repeated the measurements with the belt off.

Rattle is stronger after warm-up. When cold it is almost mute.
When revved it disappears completely. Even when revved only a bit, let's say 100-200rpm (hundred, not thousand!) more!

So i guess the chain is stretched a bit, but since your is working fine, i guess mine would to, until i will replace it.

Ferdman, are you sure it is oil pressure driven?
I don't have any tensioner schematic diagram so i can investigate that.

sharky, the Service Advisor at our local MB dealer told me the timing chain tensioner relies on oil pressure once the engine is running. Apparently an older timing chain tensioner can develop an internal leak so the tensioner does not remain fully extended, allowing slack in the chain which produces a slapping sound. A new timing chain tensioner eliminated the sound in our 1992 300CE.