E320Star

I finally took it to the dealer. The knocking sound was coming from the driver side behind the front wheel. The MB dealer checked both Cat coverters on both side. He discovered the passenger side Cat converter is the colbret. Even thu I was sure it was the driver side being the bad one !! So, they replaced the CAT converter on the passenger side free of charge since it is still under warrantee 8/80,000. That was last Friday 3/24/2006. However, the sound did not go away and it is still happening from the Driver side. It only happens when the car is cold. He told me the way to know if it is the cat, is when you start it up in the morning while the car is cold, when the idle drops after 1 minute after start it, then you will hear this knock/tap-ing sound. When he checked the driver side, he said it was not noisy when he tap-ed it while checking it out, the passenger side did. What should I do, could it be the driver side cat still? Thanks

E320Star

ANY THOUGHTS?

purplegrog

Same thing happened to me. take it back and tell them you suspect that despite the passenger side cat being replaced, you suspect that now the driver side has gone too. For me, they replaced first the passenger, then the driver side, both within 1-2 months of each other.

E320Star

Took it yesterday 4/20/2006 for the left driver side Cat. This time a diff service person at the same dealership. He tells me it is also bad !! I wonder why the other svc man told me only the right one on 3/24/2006 !! This time this svc man who is more honest he said there is a recall on both of them due to a manufacturer defect. Now I have 2 new CAT on my car which is still under warranttee. I will let you all know if this will fix the strange noice while the car is cold by next week since it is warm these days !!