2004 LC 173K...muffler/catalytic converter replacement

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T

TomR

10 Year 15 Year
Joined
Mar 23, 2007
Threads
35
Messages
117
Location
Two Harbors, Minnesota
I am on my third LC...1991/1994 and now 2004 with 173k miles.


I began hearing what I thought might be transmission problem about 6 months ago...a "harmonic" type noise only as I accelerate. When cruising on the highway it goes away when I let up on gas and returns when accelerating. My first thought was early stage of x-mission problem.

I was out by my garage the other day and my wife backed the LC out of the garage and I heard what sounded like exhaust "noise". After further listening ,etc. I now wander/think it is the muffler. Rev it up and I hear a sound I never heard before.

Any thoughts? My first thought was great...muffler is a lot less expensive than a transmission :)

Now I wonder about catalytic converter??? Might it be an expensive repair?

Any other thoughts on my diagnosis?

Thanks TomR
 
i had a rattle coming from my undercarriage and i swore i needed a new catalytic converter to make it go away. I asked around on the forum and from what ive heard its extremely rare for a cat to fail. Turns out the metalic rattle noise that i thought could maybe be my transmission (due to the fact that i typically only heard the rattle towards a gear change RPM) was my catalytic converter heat shields that were rattling. Over the years some of the fasteners rust out or come lose. Have a mechanic you trust take a look at those heat shields and i bet thats what you're hearing. If it is the heat shields then replace the bolts/fasteners and you'll be in good shape.
 
Impossible to say based on that. Have you gotten underneath the truck to inspect it? If no, you need to do that. Have your wife rev the vehicle in P and then in N. And, assuming you trust her, get next to it and watch/listen what happens when she backs up 15 feet as you move alongside of it. Then do the same going forward.
 
Whereas: You're in Two Harbors, MN where they salt the roads in the winter :hmm:
Whereas: You have 173,000 miles on a 12 year old truck :clap:
Whereas: You have new noise coming from under the vehicle that sounds like "exhaust noise" :censor:
Therefore: You should check the exhaust system and you may need everything new from the cats on back. :idea:
 
Ya...I am going to have exhaust checked. I hope it is exhaust...don't want to replace a transmission.

BTW...-20F w/-35 "windchill" this AM...if I need to inspect under the truck I will likely wait until Spring :)
 
Just to clarify...how unlikely is it that the catalytic converter needs to be replaced?? I drive quite a few freeway miles if that is a factor?

My thought is, as mentioned above, 12 years of use it is not unlikely that I need new muffler and probably cat back exhaust, hangers, etc.???

My last LC I drove 210K miles in 10 years and did not have any exhaust issues...maybe the extra two years have pushed it past its useful life. Not many cat replacements? What is Cat estimated useful life?

Still OEM exhaust/muffler parts available?

Thanks...TomR
 
Won't a bad cat through a code (check engine light)?
 
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