S205 C250 Bluetec AMG line ticking noise from rear offside when switching off

[philsmerc]

Hi

Had the car since last June and after a few weeks, I noticed that sometimes, after switching off and getting out of the car, I could hear a slight ticking noise coming under the car. It only lasts about 15 to 20 seconds and sounds as though it's coming from the rear offside of the car - somewhere between the rear of the wheel, fuel filler area - a job to pinpoint without the car on a ramp. It's quite a fast repetitive tick, tick, tick, a bit like the noise the old SU electric fuel pumps used to make when you ran low on petrol (for those who are old enough to remember). The AddBlue was topped up on the last service (November), so it's not low.

I did pop it back into the main dealer where I purchased it but of course, it didn't make the noise and the only theory they offered at the time, was that it could be the exhaust ticking as it cooled down!

With the car running fine and no warning messages, I forgot all about it for the winter but it's still doing it so when MB offered a "free" summer health check, I asked them to see if they could hear/pinpoint the noise.

I even went to the trouble of leaving the car running so they could take it straight in to check - which they did, but guess what, "we couldn't hear any noise but checked that there's nothing loose or hanging"! Of course, on getting back home, the ticking was there!!

The car is in warranty until November so I am keen to find out if this noise is "normal" or not. So if anyone with the same model has noticed the same noise, please let me know.

Thanks
Phil

 

[Headhurts]

Can't help Phil, but my E350 S212 makes all sorts of clicking, whirring and motorised noises on switch on or off.

Robin


Sent from my iPad using Tapatalk

 

[SW18]

This does sound like a noise the exhaust could make as it cools down and the various parts contract. I seem to recall it from cars that I have had in the past, though I can't recall any specifics. I'll try to listen out next time I drive somewhere!

 

[philsmerc]

This does sound like a noise the exhaust could make as it cools down and the various parts contract. I seem to recall it from cars that I have had in the past, though I can't recall any specifics. I'll try to listen out next time I drive somewhere!

I too have had ticking type noises from exhausts on cars in the past but this is more of a mechanical ticking noise. I wondered if it was either something from the braking mechanism or the add blue system?

To be honest, if they'd said it was normal, I wouldn't be too concerned as everything is working fine. Just my electrical/mechanical background niggles for an explanation. Tried recording it on my phone but doesn't really pick up the sound loud enough to be useful.

 

[GeeJayW]

I'll have a listen to ours next time I drive it. Must say I've not noticed it ticking so far.

 

[uumode]

I've had a C250 AMG Line saloon for an extended loan over 2 days, did not notice any noise, except for the wind noise from the doors at motorway speeds but that's a different story.

 

[philsmerc]

Update

I popped back to the dealer again today. I left it running (again) but this time, got them to get 2 techs to come out and listen on switching off, whilst I stood there.

They heard it this time and they reckon that it's the add-blu injector doing it's thing and quite normal!

Got there - eventually.

 

[GeeJayW]

Update

I popped back to the dealer again today. I left it running (again) but this time, got them to get 2 techs to come out and listen on switching off, whilst I stood there.

They heard it this time and they reckon that it's the add-blu injector doing it's thing and quite normal!

Got there - eventually.

Thanks for the update. Interesting.

I've noticed that ours does this clicking too, but a bit puzzled as to why the add blue injector would be active with the engine switched off. Will have to investigate. It's definitely not the exhaust cooling down (IMHO of course).

 

[philsmerc]

I rang MB UK customer support up today and the friendly adviser spoke to one of their "techies", who reckoned that he didn't think the adblu injection system would be working after switch off. He did say that on the C250, there is some sort of cooling system for the exhaust back box and it may be this that we are hearing (not obviously being present to verify)?

I wonder if any of the indies on this forum have a view?

Phil

 

[ManiacGT]

What I’ve learned over the years is to wait until it breaks or drops off because otherwise it’s usually worry for worry’s sake.

 

[Andyfkettle]

Had our S205 C250 bluetec estate for two weeks now and heard the exact same thing for the first time last night! so whatever it is is a common thing wether it should do it or not!
I am just as interested to find out what it is though!

 

[philsmerc]

What I’ve learned over the years is to wait until it breaks or drops off because otherwise it’s usually worry for worry’s sake.

Would agree, provided "it" doesn't fall off whilst giving it a Turin De-coke"

 

[philsmerc]

Had our S205 C250 bluetec estate for two weeks now and heard the exact same thing for the first time last night! so whatever it is is a common thing wether it should do it or not!
I am just as interested to find out what it is though!

We may never know. Just debating whether or not to take out the Tier 1 extended warranty at the end of November.