Rattling under car in Drive but not Park - Cats, or?
08-14-2012, 04:03 PM
#1
Junior Member
Thread Starter
Rattling under car in Drive but not Park - Cats, or?
Hi guys,
Right now I hear a pretty loud raspy rattling under the car when stopped/idling. If I put the car in park the rattling goes away. I immediately thought Cat converters but I didn't get why I don't get the sound in Park.
Is this the cats going, or another problem?
I know there is a "cat test" where I can tap on them with a rubber hammer and try and listen for a rattle, right?
Any advice/knowledge is greatly appreciated!
Right now I hear a pretty loud raspy rattling under the car when stopped/idling. If I put the car in park the rattling goes away. I immediately thought Cat converters but I didn't get why I don't get the sound in Park.
Is this the cats going, or another problem?
I know there is a "cat test" where I can tap on them with a rubber hammer and try and listen for a rattle, right?
Any advice/knowledge is greatly appreciated!
08-14-2012, 05:05 PM
#2
MBWorld Fanatic!
two things I would check mate,
1 - Check the alluminium heat shield above exhaust fixed to the underside of car. These come loose around the fixings, use some mastic or anything to hold them back up .
2 - check the exhaust brackets for loosen fittings.
1 - Check the alluminium heat shield above exhaust fixed to the underside of car. These come loose around the fixings, use some mastic or anything to hold them back up .
2 - check the exhaust brackets for loosen fittings.
08-14-2012, 10:20 PM
#3
MBWorld Fanatic!
Join Date: May 2007
Location: Nebraska
Posts: 1,435
Likes: 0
Received 0 Likes
on
0 Posts
99CLK320,
In park the rpm is two to three hundred rpms(or more) higher and proabaly enough to smooth out whatever is rattling. Look at the tachometer rise when you shift into park. How many miles on your exhaust? Jack the car up and tap on the cats(front and back) as well as the resonator and muffler with a rubber mallet and see if you can hear anything. it could be the heat shield as well.
08-15-2012, 03:13 AM
#4
Junior Member
Join Date: Dec 2007
Posts: 41
Likes: 0
Received 0 Likes
on
0 Posts
1
I agree exactly with what is posted above--most likely its the exhaust bracket. I noticed this on my car a few days after I got my new exhaust installed--seems to be at the center of the car but I need to find a way to get underneath and tighten it. Better yet, do you guys know if i can just tighten it or something that calls for a replacement? I just haven't had a chance to lift my car so can only see it rattling from the sides when the car is on the ground--no idea the extent. Let me know and thanks!
08-16-2012, 01:23 AM
#6
Junior Member
Thread Starter
163,700 miles. I have started to notice it in park but only a little. I'll try to get under and see if anything is loose on the exhaust bracket.
Trending Topics
08-24-2012, 09:53 AM
#8
Senior Member
Agreed about the exhaust heat shield. I had this problem with my 430 a while back. The shield was hanging loose and rattling against the exhaust pipe. After welding it back in place it came loose again, so I just wrapped the section of exhaust pipe with some high temp exhaust wrap (the stuff used to insulate headers and motorcycle exhaust pipes).
