DuaneC63

I don't know if any one here is following the issue with defective head bolts on the M156 engine. However I am cross posting this from the C63 board. All M156 up to a certain engine number are subject to this failure. MBZ-USA will not retro fit with the new head bolts until they fail (snap off) causing the head gasket to fail. Rapid loss of coolant into the cylinders(s) is the first indication of the problem. Failures usually occur between 40K and 50K miles. The cost to repair is very expensive if you are out of warranty. MBZ-USA has a service bulletin out on this but will not provide a copy to customers. If any of you have had this problem please send me a PM. I am pursing this further. I would suggest a letter writing campaign to:
Mr. Ralph Fisher
Mercedes-Benz USA LLC
Customer Assistance Center
Three Mercedes Drive
Montvale, NJ 07645-0350

drv2500

Did you file a complaint to Mr. Fisher?
I just saw your message and I have the similar problem. I have a ClS 500 at 37,000 miles it has a "valve cover gasket leak". I have all of the required services done at authorized MB dealer. The dealer told me it is common because rubber gets old. Are you kidding me. The car is only 6 years old with less than 40k miles. It definitely a quality issue.

How did Mercedes respond to you?

Thanks.

mbelite1

There is a HUGE difference between a head gasket and a valve cover gasket. We used to see valve cover gaskets ALL the time. They are no big deal and if your a little handy you can save the labor and do them yourself. Last one I did took less than an hour for both sides.

The Head Gaskets are a cause for concern. If you need the bulletin from StarTech info let me know and Ill email it to you.

Good luck everyone.

drv2500

Thank you for your information. I know very little about fixing car but I will ask my friend to help me. If possible please send me the bulletin. Very appreciate you spent the time to explain and reply.