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mariesilver7

Viano gasoline engine knocking and power loss

My 2012 Mercedes Viano with a gasoline engine is acting up It's got 176118 km on the clock, and lately, it's developed this nasty knocking sound, almost like a metallic tink tink tink, especially when I accelerate Power is way down, and it feels like the whole van is about to shake itself apart when I put my foot down Plus, it's puffing out smoke when I accelerate hard I plugged in my cheap OBD reader, and it's showing some error code, but nothing specific Could it be bad gasoline or something I'm starting to think it might be pre-ignition or something related to the combustion chamber Anyone else experienced anything similar

Summary of the thread

A 2012 Mercedes Viano with a gasoline engine developed a knocking sound, power loss, and emitted smoke during acceleration. The issue was suspected to be pre-ignition caused by carbon deposits in the combustion chamber. A local shop confirmed the diagnosis and performed a combustion chamber cleaning, resolving the problem and restoring the vehicle's performance.

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4 comment(s)

elias_kaiser88

I understand your frustration I have experienced similar symptoms with my Mercedes Vito, although I must clarify that I have not confirmed the build year to be the same The reduced engine power, jerking during acceleration, and presence of smoke suggest a potential issue related to the combustion process The knocking sound you describe could indeed be engine knock, possibly stemming from pre-ignition This can be caused by deposits within the combustion chamber altering the ignition timing and creating hot spots Have you investigated the condition of your cylinder heads

mariesilver7 (community.author)

Cylinder heads, huh Honestly, I haven't a clue about cylinder heads Are they easy to check myself, or am I better off just taking it to a mechanic And what kind of deposits are we talking about Could it be something I could try to clean out myself with some fuel additive or something

elias_kaiser88

While a visual inspection of the cylinder heads might offer some insight, a proper diagnosis would likely require specialized tools and expertise to assess the combustion chamber and valve condition accurately Regarding the deposits, these typically consist of carbon buildup resulting from incomplete combustion Although fuel additives may offer some cleaning action, their effectiveness in resolving significant pre-ignition issues can be limited Considering the symptoms you've described, including the error code and reduced power, I would strongly recommend consulting a qualified workshop to perform a thorough diagnostic assessment It may prevent further damage

mariesilver7 (community.author)

Thanks for the advice I took it to a local shop, and they confirmed it was carbon deposits in the combustion chamber causing pre-ignition, just like you suspected They did a combustion chamber cleaning, and it cost me about 425€, but now it runs like a champ again No more knocking, power is back, and no more smoke Really appreciate your help

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MERCEDES

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VIANOVITO