Cat rattles - JeepForum.com
Search  
Sign Up   Today's Posts
User: Pass: Remember?
Advertise Here
Jeep Home Jeep Forum Jeep Classifieds Jeep Registry JeepSpace Jeep Reviews Jeep Gallery Jeep Clubs Jeep Groups Jeep Videos Jeep Events Jeep Articles
Go Back JeepForum.com > Models > Jeep Grand Cherokee & Commander Forums > ZJ Grand Cherokee Forum > Cat rattles

Introducing MONSTALINER™ UV Permanent DIY Roll On Bed LineRubicon Express Suspensions from CCOR 706-207-4140Smittybilt Hard Tops @ Oconee Off-Road! 706-534-9955

Reply
Unread 03-27-2013, 08:46 AM   #1
Kingr98
Registered User
1998 ZJ 
 
Join Date: Dec 2012
Location: Madison, AL
Posts: 399
Cat rattles

I have searched for information on Catalytic Converters, but could not find an answer to my question:

Does the simple fact that my cat is rattling mean that I am doing damage to any other part of my Jeep? My mileage is great (over 21mpg on hwy) and my power seems to be good (especially for a 4.0). So I have seen none of the other issues that people write about with a bad cat.

Other than sounding annoying, is there any reason for me to replace it?

Kingr98 is offline   Reply With Quote
Unread 03-27-2013, 08:57 AM   #2
KoreaZJ
Registered User
1994 ZJ 
 
Join Date: Aug 2011
Location: GANGNAM STYLE
Posts: 2,666
Quote:
Originally Posted by Kingr98 View Post
...Other than sounding annoying, is there any reason for me to replace it?
If it won't pass emissions testing.

Mine rattled for several years, still passed emissions, and drove the neighborhood dogs crazy.

Had some work done at a local tranny shop, they heard the rattling and thought they had broke it. So they opened it, emptied it, and welded it back together! Had to replace it then.

The rattle noise is really annoying, it happens at low speeds, easy for everyone to pinpoint the source.
KoreaZJ is offline   Reply With Quote
Unread 03-27-2013, 09:13 AM   #3
zjosh93
Registered User
1993 ZJ 
 
Join Date: Aug 2010
Location: Austin
Posts: 1,187
Just rattling isn't an issue but probably at some point the honeycomb will end up perpendicular to flow and you will get the bad cat symptoms. Like KoreaZJ mentioned it might be several years but it happened to a friend of mine after about a week. When mine started rattling I ordered a new cat that night and welded it in that weekend.
zjosh93 is offline   Reply With Quote
Unread 03-27-2013, 09:20 AM   #4
Kingr98
Registered User
1998 ZJ 
 
Join Date: Dec 2012
Location: Madison, AL
Posts: 399
Thanks. They don't test emissions here in Alabama, so that is not a concern.

It has rattled for a few years now. I can deal with it most of the time, but it is really annoying when I am trying to place an order at a Burger King drive thru...

I just wanted to make sure that I wasn't hurting anything (other than my ears) by putting this further down on my priority list as long as I don't get the other symptoms.
Kingr98 is offline   Reply With Quote
Unread 03-27-2013, 01:39 PM   #5
Myusername1674
Web Wheeler
 
Myusername1674's Avatar
1995 ZJ 
 
Join Date: Dec 2011
Location: Chattanooga, TN
Posts: 2,200
Have you gotten under the Jeep and looked at the cat? Mine rattled like crazy. I looked under it, ended up being the welds to the heat shield on top of the cat had broken, and the sheild was sitting there rattling. When I got the Jeep aligned, Sears was kind enough to take the dumb shield off. No problems with it off. ('Course that was in the cold weather)

I ended up replacing the stock cat with a high flow magnaflow one off amazon for like $60
__________________
95 FiveTwo ZJ, DD, Lifted, Locked on 35s, Build (in progress)

My 5.9 swap (in progress)

Want your zj to be doorless in 60 seconds?
Myusername1674 is offline   Reply With Quote
Unread 03-27-2013, 06:12 PM   #6
KoreaZJ
Registered User
1994 ZJ 
 
Join Date: Aug 2011
Location: GANGNAM STYLE
Posts: 2,666
Quote:
Originally Posted by Myusername1674 View Post
...I ended up replacing the stock cat with a high flow magnaflow one off amazon for like $60
Cheap. My direct fit Magnaflow from Amazon was $108 in 2011.


One temporary solution I read was to drill long sheet metal screws into the cat so they would hold against the inner elements to prevent rattling. Anyone try this? I figured it would just make an already rattling cat leak and make more noise.
KoreaZJ is offline   Reply With Quote
Unread 03-27-2013, 06:17 PM   #7
zjosh93
Registered User
1993 ZJ 
 
Join Date: Aug 2010
Location: Austin
Posts: 1,187
The direct fit ones are more expensive but you can get the universal Magnaflows for about $60. I bought the 2.5" cat and welded it in myself. I've gotten the Jeep smogged a couple times since then and it blew fine. I think the stock pipes are 2.25" but I'm planning on replacing the whole exhaust with 2.5" mandrel bent stuff at some point. On the plus side I was able to correct the twist the previous owners shop welded into it while I was in there.
zjosh93 is offline   Reply With Quote
Unread 03-27-2013, 08:47 PM   #8
phishy
Registered User
1995 ZJ 
 
Join Date: Jul 2012
Location: Wildomar, CA
Posts: 49
I just replaced mine yesterday. It was rattling and the noise alone was worth the 130 bucks installed for a new cat. Now no more rattling...and my exhaust sounds healthier. Did find out I have a bad exhaust manifold gasket on the pass side though...its leaking a bit.
phishy is offline   Reply With Quote
Unread 03-27-2013, 11:30 PM   #9
Myusername1674
Web Wheeler
 
Myusername1674's Avatar
1995 ZJ 
 
Join Date: Dec 2011
Location: Chattanooga, TN
Posts: 2,200
Quote:
Originally Posted by zjosh93 View Post
The direct fit ones are more expensive but you can get the universal Magnaflows for about $60. I bought the 2.5" cat and welded it in myself. I've gotten the Jeep smogged a couple times since then and it blew fine. I think the stock pipes are 2.25" but I'm planning on replacing the whole exhaust with 2.5" mandrel bent stuff at some point. On the plus side I was able to correct the twist the previous owners shop welded into it while I was in there.
Universal one's cheap, I clamped mine on. I need to use some rtv or something as it isn't sealed very well. OH well.
__________________
95 FiveTwo ZJ, DD, Lifted, Locked on 35s, Build (in progress)

My 5.9 swap (in progress)

Want your zj to be doorless in 60 seconds?
Myusername1674 is offline   Reply With Quote
Unread 03-28-2013, 01:44 AM   #10
Uniblurb
Web Wheeler
 
Uniblurb's Avatar
1996 ZJ 
 
Join Date: Jan 2012
Location: Central, Ohio
Posts: 3,486
Since I'm just running a stock exhaust I went with the below Walker cat which is more expensive but it's direct fit and stainless steel. Maybe it's not high-flow like the Magnaflows but it's definitely not as restrictive as the OE cat and has a little more throaty sound.

While pricey at Advance for $121.99 you can enter the TRT41 code in the cart for $40 off for total of $81.99 plus tax w/free shipping. Just ran it through as a test for a 98 4.0 and the code works.

http://shop.advanceautoparts.com/web...14983|L3*15311
__________________
96 4.0 ZJ Laredo, 2004 4.7L WJ Limited, 93 4.0 XJ (spare), 96 4.0 XJ (son's)

-Stalling ZJ? 12 things to check before replacing a sensor; the Dirty Dozen
-Crankshaft position sensor multimeter test. & video of testing.
Uniblurb is offline   Reply With Quote




Jeep, Wrangler, Cherokee, Grand Cherokee, and other models are copyrighted and trademarked to Jeep/Chrysler Corporation. JeepForum.com is not in any way associated with Jeep or the Chrysler Corp.