roeby1

Hi everyone, I’m new to this and unsure how things work in your forums so forgive me if I’ve not posted in the correct section or repeating an already answered question.

I recently purchased a C350cdi amg sport 2012 (w204) it has covered 97k miles, has no history of issues recorded that I’ve been made aware of, I’m using premium diesel (BP garage) along with Millers Diesel Power Ecomax one shot, hoping to help give things a spruce clean from what ever the previous owners used in the car.

So my issue is, I’ve noticed on several occasions now when sat at the lights or stationary idling, the car starts to shake, it gets worse (more violent as you may say) until a change in noise from the engine and it suddenly stops but one rev with the accelerator and the shaking starts again. When driving, no vibrations or shaking can be felt but the tone in the exhaust sounds a lot deeper (this is how I can tell when the car will shake, soon as I hear the exhausts tone change I then know when I next come to a stop, the car will begin shaking). I also noticed there is a hot smell coming from the car when this happens, I can’t describe the smell as it isn’t a burning smell it’s just a hot smell and you can feel the car giving off heat if that makes sense? I’ve had a diagnostic done on the car to check the injectors and also any error codes but it came back with nothing, the issue didn’t occur whilst it was in the garage. I have searched the internet and rang around a few garages but nobody has been able to point me in the right direction, it doesn’t seem anyone has come across this issue, I used to have the c220 cdi 2011 w204, had it for 6 years with not one fault on it so it’s confusing me as to why I’ve got this issue on this car all the same spec apart from the engine size and at the minute doesn’t seem to be an issue that can be resolved. I’m hoping someone on here could tell me otherwise or at least point me in the right direction to getting my car back to its 100% self. I’m going to try and get a video the next time this shaking occurs and could maybe upload it to help people see what’s actually happening.

Any help is appreciated. Thanks

speedlimit

Hi and welcome to MBWorld!

Thank you for your introduction!

Moving your post to a forum for help from fellow owners. Good luck!

Bob

alecmascot

Could it be doing a DPF regen ?

roeby1

Hi, thanks for the reply mate, I funnily enough spoke to a MB specialist this morning (not the first) who also mentioned this being a possible reason. The thing is, most regens go unnoticed from what I’ve read online (correct me if I’m wrong) and they tend to happen every 300/500 miles, this issue I’m having has happened several times (maybe 5 to be exact) and I’ve only covered about 1000 miles in the car since purchase. I’m going to take it to the specialist as he said he can plug in and obtain information from when the last regen was performed and confirm if it was successful or not, this could explain why it happens more frequently as it is being aborted and then tries again when the conditions next suits, also any error codes regarding the DPF. With my previous C220 cdi I never came across this issue or even noticed a regen that’s why it’s confusing me more (I covered 50k over 6 years in that)

I’m also going to do an oil/filter change as I’ve noticed the oil is well above it’s max level and I’m not sure what oil has been last used or when the filter was changed (anything can be put on paper but whether it has been done is another thing I suppose) Not sure if this would cause any of my original issues but there is no harm in trying and it can only do it good.

cyberdyne

I had the exact same issue with my C300, felt vibration when at a stop and a bad burnt smell.

The root cause was both engine mounts were worn, but not yet broken and three very small oil leaks.

roeby1

Hi, thanks for the reply, I had it in with a Merc specialist yesterday, he couldn’t find any faults on plug in but found an oil leak I’ve got pictures and I saw it with my own eyes, it isn’t a small one unfortunately (massive job on these apparently due to the labour involved, stripping everything to get to the £5 seals that need replacing, which fix the problem) £1000 job, not the best news I’ve heard recently lol, but with what you have just said, it could help with the original issue once fixed so I’ll have to bite the bullet and go for it, it needs doing regardless.

Whilst doing a fix on the leak though, he is willing to remove the DPF and get it checked for blockages free of charge, if there is one, this could also be a contribution to my issues so that could then be professionally cleaned, but that is at a cost of £300.

I have done a little research on the engine mounts and from what I’ve read and investigated on my car I can’t see any issue with them, but I may suggest the guy looking at them whilst work is being done on the car as a secondary check for peace of mind.

Love the car but having only had it a few months it’s costing me more than I anticipated.

cyberdyne

Ouch, never good news when the bill is quadruple digits...

In my case, the engine mounts visually were good but closer inspection found them to be worn out. The dealership took care of this under my extended warranty and I did not get a chance to get the particular but it does bear strong similarities to your issue.

Nothing out of hand came up when scanned via XENTRY this was just old fashioned mechanical troubleshooting.

roeby1

Haha I used a selective choice of wording when he dropped the price bomb on me but I understood why it is costing so much, it says it’s a full days work if not more if you research it online.

I will definitely get him to have a close inspection of the mounts when work starts, I appreciate your input on my post and issues, thanks mate