Engine knocks during cold start.
 

I have a CLK430 with 80000 miles on it. When I start in the morning I heard some knocking ( sounds like valves or head noise). But the noise will completely goes away after five minutes or when the engine is hot. I brought it to the MB dealership and they said that it's carbon buildup that cause the knocking. They said they need to remove the head to decarbonize it. I don't know if it's a good thing to do or is that the cause of the problem. Should I do any more reasearch before decarbonize it? Also, does 1999 CLK430 have a 8/80 warranty on the catalytic converter? Thanks.

Strange
 

Hi I have the same car with approx the same Miles ( 170.000 Km) mine do the same sometimes just when cold and for few seconds (max 15s).
Never when hot, in my opinion are just the hidraulic lifters and i am not sure about carbon in heads.........if the car was mine i never take down heads for this if i ma not sure........this is a big job.
With the new fresh oil the situation is really better .
Alberto

If it is carbon buildup then you should be able to see that with a borescope. I got one shown on www.provision100.com and it is pretty good. The 45 degree mirror lets you see to the side and I could see the cylinder head and valves. I got it at my local auto parts store for 229.00. Not positive if you could see carbon but I assume you could.

Mike