LeeB41

I have a 2010 ML350 with 5,00 miles that has an engine knock on start up. It sounds like a bearing knock and lasts about 2-3 seconds. It is in for service now and I have been contacted by the service rep and told that this is a "normal noise for this vehicle". I have asked for detail as to what and why this knock is occuring. I have also asked for an official MB statement that this is a normal engine characteristic and will not affect engine life. I have never owned another new vehicle that has had this problem. Has anyone else experienced this problem?

shogun2010

Both of my C300 and ML350 making the same noise. When I start my car after it has been fully warmed up and sat for a couple hours it makes a knocking noise that goes away after about 3~5 seconds. I've never heard anything like this before, not on my aunt's GLK, not on my cusin's C200 CGI. When I mentioned it to the dealer for the A service, they couldn't duplicate the problem. I don't think it is actually engine knock, because the sound slows down and fades away after it is started.

After repeating visits to my dealer, they probably got fed up and finally told me the noise is made by bearings which can be fixed by replacing it, but the dealer guaranteed nothing. Therefore, I am not so sure is I should go ahead and replace the bearings because they are not 100% sure it is caused by the improper sized bearings. I feel there is something to do with the under-pressured oil at start-up. I actually has a sound record of this noise with me, let me know if you interest in listening to it.

shogun2010

By the way, I have a sound record posted here. Please listen and see if we are talking about the same noise or not.

http://www.benzworld.org/forums/w204...-start-up.html

amg305

I have the same noise on my 09 E350 but dont know if we all drive these the same way. It sounds like a rod knocking inside the block but it fades after a few seconds . Lease is up soon : )

Benzo 003

There are internal "knock" sensors within the engine that will quickly adjust the engine"tune" to eliminate knock. From what I've read, knock within these engines usually comes from from using lower octane fuel than recommended.

At start up, the engine may be "knocking" and the tune gets adjusted to compensate....my 2 cents.

tcesario

it is the camshaft adjusters ,they retard at start up,it causes a slight rattle /knock noise briefly ,normal operation for this engine ,