On my 2000 E320 which has 69000 miles, i am experiencing engine knock/ticking when it is cold. It seems like the knocks have increased from 3 yrs ago. I always premium unleaded, Mobile 1 Synthethic oil changes every 5000 - 6000 miles. The car does not smoke nor have any other symptoms. Could it be a vacum issue some where? or an air pump? where are these things located ? Thanks.

 

There is a purge valve that ticks on the drivers side of the engine. Annoying, but normal. Can be replaced which may/may not solve the problem.

 

I experience the same issue during colder Midwest weather. Please give me more info on the purge valve's function and location on the engine. Thanx

 

It's labeled MOT and is behind the washer fluid tank. It is a vacuum purge valve and has wires connected to it. Not sure what it does except make noise and trigger the check engine light when you disconnect it. Search for "MOT clicking" on this board and/or others

 

Thank you. I'll do the search.

 

It is really wierd. when i start the engine for a 2 sec's a ticking sound goe saway immediately. That is normal until th enegine is lubricated. But after 1-2 minutes the clicking sound which lasts until the engine is normal heating temp. Do u still think it is the MOT purge valve? do u have instructions on how to replace it? Thanks

 

Open the hood and listen where its coming from. It's pretty obvious when its the MOT valve. you can put your hand on it and feel it clicking. It's not abnormal for valve lifters to click for a few seconds until the oil pressure builds up but its probably your MOT

 

Im experiencing the same issue. The ticking does go away after a few seconds though. Occasionally it will go on until the engine has reached its normal operating temperature. I dont have any issues with performance, so im guessing its not a big deal. Just kinda annoying.

 

a diy purge valve cleaning and check over on benzworld.org w210 diy section.The purge valve comes on as a test for your emissions system and then as required to purge excess fumes from the fuel system.locate it by my pictures and listen to it clicking along at start up.It most likely is not the source of your engine noise,it really is not that loud
ohlord

 

The initial ticking is fine with me. I do not think it is the MOT. MOT has a didstuguesed sound. No issue with car perfomance. it is just annoying for 10 minutes of this sound until it fully warms up !! to me a $50k shoould sound a lot better than a Camry at least !!

 

My car had the same problem. It was ok when I was accelerating or at least moving. But when I had to stop at a red light when the engine was cold it started shaking back and forth. As the engine warmed up the shaking decreased but I could still hear that the engine was not running smoothly. First they changed the MAF sensor but that made no difference then they found that MAT was disconnected. (Actually I had no idea what they were doing I am still learning) They plugged it in now the engine has no hesitation neither cold nor hot now. If I am not wrong oil consumption decreased about 20%. As a new owner I was satisfied with the way my car run when it had the problem. After all it is 10 years old. But now I am thrilled with my car. So this problem although seems minor to a new owner better be fixed then left alone.