Hi everyone - first time on forum. Have 3 1/2 yr old Merc SL 500, c.35,000 miles. 3-4 weeks ago developed clunking, rattling noise, especially when warm, although not consistent. Doesn't appear to effect performance, but is very disturbing. Just returned from a national exhaust shop - quick look underneath, a few taps and they think it's the cat. convertor as they do rattle when knocked by hand.
(a) does this sound like a cat. problem at all ?
(b) what causes the problem (not aware of any accidents) ?

(c) what should I expect to pay ? would I need a complete exhaust system ?
(d) shop suggesting 'after market' parts - what do you think ?


On another note - am thinking of taking extended warranty with WarrantyWise - any comments / points ot be aware of ?

Many thanks

 

yes It sounds like someone dropping marbles into a tin can when you accelerate, I had this done twice on my 02 CL 500 at the same mileage as you . the converter on my old camaro lasted the life time of the car.

 

Mercedes-Benz hasnt build a quality exhaust system yet. Your car might be covered under the emissions warranty. 7 years or 70,000 miles. The material in the converter gets wet from condensation and then drys up from heat. After so many times of getting wet and dry and wet and dry, they tend to become brittle and brake. The welds on the catalitic converter also dent to crack.

 

If you park on long grass this will cool down the outer case before the ceramic cat , and it crushes it,also on low milage cars the cats do go, do not know where you live but in the UK they cost £615 each side (v6) I bought some with a wire mesh cat for half of Mercedes price,and will not have the same problem again