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.

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

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1998 C230 330,000 miles (currently dead of second failed EIS, yours will fail too, turning you into the dealer's personal human cash machine)
1988 F150 144,000 miles (leaks all the colors of the rainbow)
Previous stars: 1981 Brava 210,000 miles, 1978 128 150,000 miles, 1977 B200 Van 175,000 miles, 1972 Vega (great, if rusty, car), 1972 Celica, 1986.5 Supra