2012 Mercedes-Benz M-Class Consumer Review: Engine noise on warm startup

2012 Mercedes-Benz M-Class - Consumer Review

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Engine noise on warm startup
By ml350owner on


2012 Mercedes-Benz M-Class ML350 4MATIC 4dr SUV AWD (3.5L 6cyl 7A)


Hi , I read many reviews or complaints regarding the famous engine noise or knocking that lasts 2-3 seconds only on warm start up after the car has sat for 1-2 hours but not completely cooled yet.I believe I have the explanation for it since I had the same thing in my old 1991 E260, simply the problem is that mercedes uses an oil pressurized system for the variable camshaft timing of the valves, there is different setups for cold or warm start guided by the car computer, in cold start system is fully drained but pressure not needed in that system for cold cam timing, in immediate restart system still fully oil pressurized so no noise, in between u hear the noise, no effect on engine life :-)

Best Features

Love the car and would continue buying mercedes, excellent value for money among premium cars. I love the tech features like auto dimming the HVAC when I'm using voice command so no problem for car hearing my voice, also like auto start rear windshield wiper on reverse if its raining, blind spot monitor is a must, lane keeping assist is cool to have but not always necessary. The brake pads dry itself in rainy days to keep always maximum braking power when needed Also love the instrument cluster screen which shows nav prompts as well as controlling everything from the steering

Worst Features

I wish I can say the whole destination address once for the navigation rather than steps (city, then street, the address , following the voice prompts) I also hope they add heads up display option I hope they change that oil pressure valving system in the V6 to a different design (just like their V8's) so the car wouldn't knock and I wouldn't have to keep explaining it to my friends !
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