turk11

I understand there may be a service bulletin describing a condition, where a slight pre-ignition clatter occurs for a short time during cold start-up. If anyone experienced this condition is there a remedy or is it benign?

kfehling

I have been experiencing this on my 2006 C55 as well as my 1996 Corvette. All of these cars (including yours) have one thing in common, Mobil 1 oil. It is normal. However, you should take it easy on the engine until it goes away. The theory that I have heard is that the Mobil 1 is so thin that it drains out of the top of the engine easily and until it is pumped back up there, we experience this clatter.

shandy2550

Although this may sound like pre-ignition clatter ;as the previous poster says it comes from the valve gear ; these motors use hydraulic valve lifters which can drain of oil and take a few seconds to refill on startup especially when using very thin synthetic oil . Do not put any load on the engine until the noise disappears.
Geo.

turk11

Thanks for the info. I'll keep off of it until it settles down.
Turk11

mikec230

my 06 c230 does the EXACT same thing... i bought it used and thought I had a defective car.. but the thing only has 8k miles on it haha..

the noise goes away after about 5 seconds and only happens if the car has been sitting for 4hrs or more

TonyG230

MikeC230, my C230 makes a rattle noise at start up but only if left sitting for a week or so. My car is an 02 model with the 2.3 liter engine, different then yours. I have been under the hood and had my hand on the valve cover when the noise happened and felt the timing chain hit the underside of the valve cover with a vengence but only for 2-3 seconds. Is your noise the same and have you had it to the dealer? I don't like it but think bleeding down of the oil is the problem. Funny thing with my car is that it didn't do it at first till I put miles on the car and after the first year,Oh and I only have about 12,000 miles on my car. I'm not a happy camper!!