Need help with diagnosis of rattle.
#1
08-18-2013, 09:10 AM
Need help with diagnosis of rattle.
Okay, I have had an interesting rattle for a little over a year on my 1999 Audi A6 2.8 Quattro. It occurred one night as I was driving back down from Blackhawk, Colorado, and has been there ever since.
I took it to a mechanic and they claimed (inaccurately, might I add) that it was due to a small hole in one of my catalytic converters. They welded it up, yet the rattle persisted. I took it to another mechanic recently, and his diagnosis was a bit more along the lines of what I am thinking:
A) It's either a broken piece of the flex pipe on my right catalytic converter
or
B) It's coming from the engine heat shield (I REALLY don't want it to be this one).
I'd prefer not to get the diagnosis wrong and work on one, only to find out that it's the other, because both are annoying jobs. Basically, I have some clues that may help figure out which one it is.
1) Sounds like a small piece of rock or metal in a soda can.
2) It only makes the sound when I initially start up the car, and when I accelerate. The sound is VERY faint (almost to the point of non-existent) when I am slowing down. When I idle, it returns, but very lightly.
3) It seems (keyword: seems) like the higher the gear I'm in, the less sound it makes.
4) I hear it loudly when my passenger window is open and I pass by cars and trucks, but can only hear it somewhat when my driver's side window is open (as a result of this, I'm pretty sure it's emitting from the right side of the vehicle).
I hope this helps narrow it down a bit. I'm contemplating just taking off the right catalytic converter to test it out, but after having DIY'd my cats about 2 years ago, it's a process that I'd prefer not to go through again without being 100% certain it will fix the problem.
Thanks in advance!
I took it to a mechanic and they claimed (inaccurately, might I add) that it was due to a small hole in one of my catalytic converters. They welded it up, yet the rattle persisted. I took it to another mechanic recently, and his diagnosis was a bit more along the lines of what I am thinking:
A) It's either a broken piece of the flex pipe on my right catalytic converter
or
B) It's coming from the engine heat shield (I REALLY don't want it to be this one).
I'd prefer not to get the diagnosis wrong and work on one, only to find out that it's the other, because both are annoying jobs. Basically, I have some clues that may help figure out which one it is.
1) Sounds like a small piece of rock or metal in a soda can.
2) It only makes the sound when I initially start up the car, and when I accelerate. The sound is VERY faint (almost to the point of non-existent) when I am slowing down. When I idle, it returns, but very lightly.
3) It seems (keyword: seems) like the higher the gear I'm in, the less sound it makes.
4) I hear it loudly when my passenger window is open and I pass by cars and trucks, but can only hear it somewhat when my driver's side window is open (as a result of this, I'm pretty sure it's emitting from the right side of the vehicle).
I hope this helps narrow it down a bit. I'm contemplating just taking off the right catalytic converter to test it out, but after having DIY'd my cats about 2 years ago, it's a process that I'd prefer not to go through again without being 100% certain it will fix the problem.
Thanks in advance!
#2
08-23-2013, 04:36 PM
99 A6 2.8 Exact same car. Exact same issues.
Unfortunately, I don't think I'll be much help to you, but you nailed the problem I've been dealing with. It's on the right side. I don't hear it over 2000 rpms typically, and it's pretty annoying when I'm parked between cars or driving slowly down the street. I haven't noticed any change in performance either. It sounds like it's a costly fix if we were to just bring it to the shop. Hoping that there's a cheaper alternative. Thanks for sharing/reading!
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