TwinCam

My 2010 E550 with 8,000 miles (original owner) has been making a loud ticking noise that increases with engine speed and does not diminish after the engine is warmed up. The dealership service department determined the noise was coming from one of the cylinder heads. After pulling the cylinder head and inspecting it, Mercedes is going to replace the head with a new one and the defective unit is being sent back to them. Should I have any concerns about this warranty repair and is there anything I should discuss with the dealer? The car runs great, (other than the ticking noise). Your thoughts and advice are appreciated. Twin Cam

NJProTech

I've seen broken valve springs on 272/273 engines. Your v8 273 is also prone to valve seat problems but I have not heard of a noise complaint with faulty valve seat. Depending on the tech and his level of knowledge and professionalism, a new cylinder head can be done perfectly or very very wrong. The sealant path use on valve covers is 1.0mm and any excess can ruin engine. I doubt a newbie would get a head job but you never know. Seen many v6/v8 272/273 cylinder heads get replaced and seen/experienced about 5 or 6 boo boos

kered

Like NJpro said, any competent mechanic should have no problems doing the job. The sealant path is critical and it changes between the 272 and 273 engines. Also if the valve covers are damaged in any way during removal the whole head will need to be replaced as they contain the cam journals. I have never come across noise complaints but again like njpro said i have had valve seal problems where the car would leak oil into the combustion chamber.