CLK500 injector noise

[x332race]

My car makes a barely perceptible noise like a rattle or ticking under accelleration.....this is not evident when engine at constant speed...
I have heard that the fuel injectors can make a ticking noise under load....can anyone shed any light on this....

The car runs perfectly otherwise...acclerates well and has reasonable fuel consumption for its size.....does not seem to burn any oil. Its a 2004 CLK 500

Is this noise normal for the 500?

 

[BlackC55]

The injector tick is aplicable to diesels only.

is it a cyclic tick?

 

[x332race]

No, its a rattle almost like "pinking" but very low key and only there under load whilst accelerating.

 

[BlackC55]

it maybe your cats rattling. Give them a tap with a soft hammer

 

[x332race]

Cats seem to be ok.

Checked heat shields...they seemed to be ok but there is a lightweight aluminium mushroom shaped thing behind the engine on the drivers side....this seems to be part of the heat shield but is fairly loose and vibrates when touched.....could this be source of sound?

Also found that the cap on the top of the dipstick tube was loose and had not been pushed home when it was last serviced.....this probably meant that the seal was not good ....could this have an effect?

 

[x332race]

After suffering almost a year of a slight rattle from the engine of my CLK500 I was spring cleaning my car over the weekend and fiddling around in the engine bay when I noticed that one of the plastic covers on top of the engine was ever so slightly loose on one side...I fiddled about with it so that it seemed to settle into position better.....have driven the car since and the annoying "rattle" on acceleration seems to have gone away....result...

This seems to make sense as I topped the oil up a month or so ago and the rattle got a lot quieter for a time after...at the time I put it down to slightly thicker oil but on reflection, I probably changed the position of the plastic covers slightly so as to reduce the rattle...the noise die come back after a period of time so I will need to find a way of fixing the covers so that they do not vibrate.

Car sounds much better without the rattle!