Rattling on W202 C180

[Tango]

Hi all quick Q

When i start up my C180 it seems to rattle quite loudly, sometimes it seems like its coming from the front passenger side and sometimes from the exhaust

also if i let it idle in neutral it idles at about 800rpm and then every 10 seconds or so it drops to 600rpm makes that rattling sound and comes back up again...

i dont know whether this could be part of the problem but if i put my foot down in neutral it only revs to just over 4000rpm and just goes up and down slightly around that mark .. wont go to redline..

any help please!

thanks!

 

[Will]

Hi Tango,

2 things:

The rattling is probably your cat - very common on your model I am afraid. Could be something else (heat shield etc) but I would personally bet on it being this.

Your car will not rev past 4K in neutral - this is normal. Does it rev past 4K whilst driving?

HTH,

Will

 

[Tango]

Hi

yeah im not sure on the revving past 4K in gear, will have to check that!

and so will my cats need replacing?

thanks!

 

[abbos]

Hi Tango,

I had a similar issue on my w202.

It was the cat. I had this replaced and all is working now. No the cheapest fix though. Roughly about £400+

 

[KillerHERTZ]

Deffo you cat, mine has had the same problem & my mechanic has fixed it, but its lilkely to go at any time

as said above £400 ish

 

[pluggers]

I would first check the manifold heat shield then the sound insulation on the bulkhead isn't touching the engine anywhere then check the cat converter heatshield isn't loose first before changing the cat converter.A simple knock with the hand on the cat will tell if its breaking up.

 

[Tango]

oh no so its more then likely a cat problem.

so should i be experiencing a loss in power gradually or somthing as the cat finally fails??

thanks again people!

 

[pluggers]

If its breaks up into chunks and gets stuck in the pipe work there will be a complete loss of power as no exhaust gasses will be able to escape.If it doesnt and just rattles there will be hardly any power loss.