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ML350 2007
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78 Posts
Discussion Starter #1
There is a strange sound coming under the hood on cold start - below the freezing point. As it gets colder, the sound stays longer. At a couple of degrees below, the noise stays on for about 1 sec. and at 20F, it increases to about 3 secs. It started last winter with 35K mi.

Is there something malfunctioning or is it normal? Comments please.
 

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There is a strange sound coming under the hood on cold start - below the freezing point. As it gets colder, the sound stays longer. At a couple of degrees below, the noise stays on for about 1 sec. and at 20F, it increases to about 3 secs. It started last winter with 35K mi.

Is there something malfunctioning or is it normal? Comments please.
Perhaps a case of oil starvation on startup, it could be that the cold weather is causing o-ring shrinkage at the oil filter allowing it to drain dry as it cools off. Then when restarting your valve train is starved until the filter is full and oil circulates properly again.
 

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2002 honda civic (sold), 2009 Mercedes ML350
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all the newer vehicles with the 272/273 engine have this issue, i have an 09 ML350 and at cold start or after it has been sitting for a few hrs after driving the engine knocks for 2-3 seconds. it has been narrowed down on 07-09 vehicles to the cam adjusters, or oil starvation to the heads, on the new 2010 e class vehicles the main bearings in the engine have been the cause to an extremely loud knock at cold start. unless the noise stays at all times i wouldnt worry about it
 

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ML350 2007
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78 Posts
Discussion Starter #5
It sound like some compressor grinding, but just a second or two.

Does anyone know what components are activated once the engine starts and then turn off in a few seconds and are affected by cold temperatures?

Thanks
 

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ml350
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I had what sounds like possibly the same thing, a "ticking" sound immediately after start-up. Turns out it was the A/C compressor (A/C still worked fine, though). Replaced by dealer under warranty.
 

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ML350 2007
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78 Posts
Discussion Starter #7
I had what sounds like possibly the same thing, a "ticking" sound immediately after start-up. Turns out it was the A/C compressor (A/C still worked fine, though). Replaced by dealer under warranty.
Thanks for the feedback! I will check w/dealer.:thumbsup:
 

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all the newer vehicles with the 272/273 engine have this issue, i have an 09 ML350 and at cold start or after it has been sitting for a few hrs after driving the engine knocks for 2-3 seconds. it has been narrowed down on 07-09 vehicles to the cam adjusters, or oil starvation to the heads, on the new 2010 e class vehicles the main bearings in the engine have been the cause to an extremely loud knock at cold start. unless the noise stays at all times i wouldnt worry about it
i have same issue on W164 2009 :) and have same knock sounds for 3-4 seconds :) and so its not a problem ?
 

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I have a 2013 ML 350 V6 Gas, it every time at start up, I hear a super loud rattling... I paid almost $2000, because they said it was the Tensioners that needed replacement.. then after the job was done, a week later the sound returned now it’s louder. It sounds like the car is slowly dying. I can’t wait to trade this in, although it’s only worth maybe $10,000.00.
 

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ml350 2008
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52 Posts
next time , while cold ,open hood and listen to the secondary airpump (electric pump, black body, next to oil filter) while you have someone else start .
It only kicks in for the first few seconds and then turns off.
If pump bearings are gone it can make some weird nosies for a few seconds.
 
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