When i start the engine in the morning and only in the cold winter even thu is garaged, there is an engine knock that eventually goes away after it warms up about 15 minutes. And only in the morning. It was not doing that when i bought it 2 yrs ago. I only used mobile 1 every 6000 miles, and it does not happen in the summer time. It is a 2000 E320 with 53,000 miles only. I am not sure if the sound is from engine, it appears to be coming from driver side under the hood. What else could it be? Thanks

 

My car does the same thing...I have a 2001 E430 with 67xxx miles. For the first 10-15 seconds, there is knocking, but that is when the oil is trying to get into the cylinders. After that, it is fine. It only does this on a cold start. If it is lasting any longer, it could be the distributor. Anyone with more knowledge, correct me if I'm wrong.

 

I remember when i used othave 1993 BMW 525, did the same thing too. I took it to the dealer and after a checkup, no issue found. The response was it is normal. But now owing an MB, is the same fricking knock !! I doubt it is normal. Anyone with this same issue and had it fixed?

 

The guy who said its motor trying to get oil is right... think about it, its been sitting (means the oil has drained to bottom of pan) AND the oil pump isnt moving.. when you start it up, all these things are compounded because nothing in the motor has much lubrication so your GOING to hear some meatal on metal knock type sounds untill everything has a chance to get lubed up, only thing ive seen people do.. is put starter delays on them (prevents fire) so you can turn key for a while and let engine get a little chance to have some lube before it fires & starts moving.

Some of those oil treatments as well as really expensive oils tend to leave a better coating to protect against this, but in the end, its something you just have to live with =)

 

How come it started to happen now and it did not before upto 50,000 miles !! Something is got to be wrong