My E320 has developed the notorious CAT rattle – of course just out of all warranties at 83,000 miles. Quotes to replace a single cat varied from $1,000 to $1,500. So I’ve decide to tackle it myself, instead of forking out all that green stuff to the dealer/exhaust shops. I’ve taken some pictures, since I think that more people will be coming into the situation where they are no longer cover by any warranty. The job took me about 2 hours.
The first step is to diagnose which side is bad. Not such an easy task as it may seem, since the 2 pipes runs just a few inches from each other and makes it hard to pinpoint the bad one. For this I used the highly complicated and technically advanced Catalytic Converter Diagnostic Device (CCDD) (Local and International patents pending)
- Photo 1
Just press the one end to your ear and the other end to the cat while the car is idling in the condition where the cats rattle – in my case the car had to be in gear, so be careful!. For a second opinion, I’ve had my son listen afterwards, while I pressed the end to the cats out of his sight and we came to an agreement on the bad side. (Well, it also helped that the left side had a manufacture date of 10/2005 and was probably replaced by the previous owner
). I would suggest that you at least have metal on one end of the hose , since those cats get extremely HOT.
The dealer wanted $850 plus for the right-hand cat, so I decided to try a non-OEM one at $595. The replacement cat has a 5 year/50,000 mile warranty. Non-California owners may have more options and can maybe elect to just to cut out the bad cat and have a replacement welded in.
The following are the tools needed for the job (photo 2) :
12 mm socket
13 mm socket
12 mm spanner
13 mm spanner
Ratchet
O2 sensor socket
Some very long extensions (12 inch plus)
Torque Wrench (Optional)
VERY GOOD STANDS OR RAMPS!!!!
You will be spending a lot of time totally underneath the car, and you are going to push and pull quite bit, so your setup MUST be VERY stable. Don’t try to skimp here – you may end up injuring or killing yourself.
