W210 (E320 V6) Rattling Exhaust

[Jack the Lad]

This was pointed out to me at the last service - the catalytic converter on one side rattling when hot. He said it wasn't urgent but to keep an eye on it. The rattle has got louder. You can't hear it from inside the car with the windows up so it doesn't bother me in normal use. It doesn't seem to affect either performance or fuel consumption.

Provided the noise doesn''t get to an anti-social level is there any harm in keep driving it until it needs doing to get through the MOT? The next service will be about 8,000 miles off and the MOT in March. They will probably co-incide.

 

[colechelle]

Can suck bits back into the engine, then your have bigger problems!!!

 

[louwdj]

Interesting. I have never heard of anything being sucked back into the engine from the exhaust. In what situation will there be vacuum (suction) when the (any) exhaust valve is open?

 

[television]

What many have done here and myself is to cut open the bottom cats and remove them and weld up again,,they have all passed the MOT

 

[Razoo]

Interesting. I have never heard of anything being sucked back into the engine from the exhaust. In what situation will there be vacuum (suction) when the (any) exhaust valve is open?

The usual culprit is the EGR (Exhaust Gas Recirculation) system, which recirculates exhaust gases (and all manner of crud) throught the engine via the inlet manifold.

The EGR system reduces combustion temperatures and NOx (Nitrogen oxide) emissions (and engine life, IMO).

Ford had a lot of trouble with the EGR systems on their early Duratec V6 engines (as fitted to the MkI Mondeo). The cats in the exhaust manifold downpipes were prone to breaking up. Small pieces of ceramic then entered the engine via the EGR system and scored the bores. Ford redesigned the cats and did a recall to replace the cat/exhaust manfold assemblies. I owned a Duratec V6 at the time and, rather than risk catastrophic engine failure, I fitted a homemade steel blanking plate between the EGR valve and the inlet manifold. The car ran a whole lot better after that modification, and the ECU never realised the EGR system had been disabled.

Read all about EGR here:

http://en.wikipedia.org/wiki/Exhaust_gas_recirculation

Razoo

 

[Jack the Lad]

What many have done here and myself is to cut open the bottom cats and remove them and weld up again,,they have all passed the MOT

Does this mean you just find out which bit of the exhaust is rattling, remove the guts and it doesn't affect either the noise level (bar stopping the rattle), the emissions test in the MoT or the engine management system?

If my usually very friendly, resourceful and accommodating local garage (which is also the MoT station) is unwilling to do this for MoT reasons, is there a source of good cheap MB exhaust catalysts that he could buy one from to fit. I'm guessing this isn't the sort of job that must be done by an M-B trained mechanic with zillions of squids worth of diagnostic equipment.

 

[television]

Your car has 4 cats,,2 in the down pipes and 2 in the bottom, we just cut mine open with an angle grinder and pulled out the damaged ceramic CAT and welded up again,, there must be 5-10 people that have done the on the V6 and they have all passed the MOT

 

[Jack the Lad]

Thanks for the advice. Might give that a go then.

 

[Jack the Lad]

My garage man has had a look at this for me. He says there are 2 cats side by side and both are rattling. Do I take it that both of these could have the axle grinder remedy if they are on separate sides but you can't do both if they are on the same exhaust run?

 

[television]

I have never heard of a rattle in the upper cats,,and it has always been the lower one or both,I took both of my lower ones out

 

[Jack the Lad]

Thanks TV, I'll get him to do the job then. The rattle is the only thing that disturbs the peace. Sounding like a bag of nails doesn't help my image!

 

[television]

Thanks TV, I'll get him to do the job then. The rattle is the only thing that disturbs the peace. Sounding like a bag of nails doesn't help my image!

The thing that got me was that in the open country, hardly any noise, but as soon as I got into a town, it was unbearable

 

[dunkardvalley]

rattle in undercarriage of E320

I have an 03- E320 that has developed a very annoying rattle in the undercarriage of the car. Originally we replaced a upper & lower control arm. This seemed to stop the rattle....but it returned. It got terribly loud again. Took it back to the dealer, they could find nothing wrong, and the rattle suddenly disappeared. Now it is back again. Just had it to the dealer, and again they could find nothing. It rattles on any type of bump, and if you listen closely can hear a little rattle on smoother roads. I live in WV, so it is hard to find smooth roads, especially in winter months. From your posts, it sounds like it my be the catalytic converters? Is it possible for that type of rattle to have disappeared for a while?

I am no mechanic. If this is the problem, I am assuming my MB dealer would not take out the damaged pieces, but rather try to sell me new parts....very expensive parts. Is this something I could get a local garage to do?

Any help or advise you can provide would be appreciated. The noise is driving me crazy!!