Timing Chain noise W202 C180 160K miles

[EdGasket]

I am getting a gravelly noise coming from the front of the engine. It is only noticeable at tickover and especially when hot after a long drive. It is loud enough to hear in the cabin with all windows and doors closed. Sounds to me like the chain might be a bit slack. Is this a known issue? Does the tensioner wear? Do I need to fix this or will it go on for another 100K miles?

 

[John Laidlaw]

Can you post the noise on here...video

 

[LostKiwi]

Google search m271 timing chain issue , there is plenty of reading , yes it is a known issue on that engine . It's an expensive fix for a garage , the parts alone can be 1k+ if the two front cogs need replacing as well as the chain .
Someone more knowledgeable will add to this I'm sure

It's not an M271 - it'll be an M111 engine so won't have the same issues.
A video clip would be useful.

 

[Wighty]

It's not an M271 - it'll be an M111 engine so won't have the same issues.
A video clip would be useful.

Well spotted sir ...my bad . I have deleted my post above , so the full extent of my error never becomes known .

 

[LostKiwi]

Well spotted sir ...my bad

Even early w203s had the M111 for the C180 while the crest had M271s.
We really need a clip of it making the noise.

 

[EdGasket]

OK I'll try and organise that but won't be until at least Friday; it is chain noise though.

 

[EdGasket]

Well I got a video but it won't upload; file too large. Anyway it wasn't that great as the chain slap wasn't so obvious today and kinda merges in with the general noise. Does anyone know the file size limit for upload here?

Also do the tensioners go bad or need overhauling like in this youtube vid:

He says he's doing it for chain noise and that the oilways may be blocked?? I thought the tensioner is just spring loaded?

 

[EdGasket]

I got a better video; its 52MB; won't upload here. Can anyone help with this or my questions?

 

[LostKiwi]

I got a better video; its 52MB; won't upload here. Can anyone help with this or my questions?

Upload it to youtube then link to it

 

[EdGasket]

This was from a cold start

 

[LostKiwi]

That sounds more like a bearing giving up to me - if you remove the serpentine belt does the noise go away?

 

[alexanderfoti]

+1 on bearing. Maybe fan clutch, more likely to be alternator or water pump.

 

[EdGasket]

It sounds to me that the noise is coming from the top of the engine; not around the accessories but I'll give the belt off a try tomorrow.

 

[LostKiwi]

In my experience timing chains tend to rattle half way down between the camshaft and crankshaft as thats the longest chain run.

 

[EdGasket]

Serpentine belt off - noise still there
Oil flush and change - noise still there
Seems to be loudest on the left side (as you face the bonnet) around the tensioner area. Do these suddenly go bad? I don't mind attempting a tensioner overhaul as per the video above or changing it but I'm not doing the chain guides which requires head off! (who makes plastic parts that can only be changed by removing the cylinder head?? - oh yes Mercedes of course!).

If I got the tensioner out, how would I know if it were bad? Does the spring go weak or ratchet fail?

 

[alexanderfoti]

I believe the tensioner is sprung with a spring. Not known them to go weak though. Wonder if the spring is broken?

What does the noise do when the engine is revved? A chain noise is normally more rattle than grumbly

 

[EdGasket]

Update: Finally got around to looking at this myself. SO:
1) The noise does disappear with the serpentine belt removed; aplogies for false info above
2) The tensioner wheel did feel a little rough on the spin so I replaced that but no difference to the sound.
3) I took a new video; see here:

The noise is particularly noticeable 7-14 secs and 33 to the end; sort of rattling; gravelly sound.
4) Alternator seems fine.
5) The viscous fan has quite a lot of play in it; I can wobble the blades a few mm.
6) I can't spin the water pump pulley; it seems stiff and I can only turn it but feels OK; just stiff; maybe because it is buried in coolant on the other side?
7) Power steering and air con pulleys OK as far as I can tell.
8) The tensioner shock absorber looks fine; I pressed it around and the noise didn't change; seems to be coming from the water pump area.

So thankfully the timing chain seems fine; bought a tensioner wheel I probably didn't need but a new one won't hurt.
Would the water pump or viscous fan be making this rattly noise? Do I just carry on driving until something breaks?

 

[LostKiwi]

Water pump can't be spun freely due to resistance of the water on the back but it should turn freely by hand (with minimal resistance). If you turn the viscous coupling by hand does it turn smoothly?

 

[EdGasket]

Yes spins in both directions with a slight clicking sound which might be the clutch?
It does seem to have less play now the belt has been refitted. I wonder if the sound is the pump impeller scraping the inside of the water pump due to worn bearing? (had that on a Corsa once, sounded like a tractor!) The fan definitely seemed more wobbly without the belt fitted.

 

[LostKiwi]

The fan has a silicone oil in it which thickens with heat.
to provide drive so shouldn't make a noise. I'd be tempted to remove the water pump and check it off the car. (or even just change it anyway).
Usually a viscous fan will be noisy when not doing any work and go quiet when the engines hot and they lock up - opposite to what you're seeing.