My XJ's problem of the week (cat. converter)

Ok, this weeks problem is the cat. converter.

It is rattling from the inside. Is this easy to gut out? Has anyone made a test pipe? Will it eventually just blow all the pieces out the tail pipe?

tnomud said:

Ok, this weeks problem is the cat. converter.

It is rattling from the inside. Is this easy to gut out? Has anyone made a test pipe? Will it eventually just blow all the pieces out the tail pipe?

Click to expand...

It needs replacement, if you have done exhaust work its not to bad. No..the pieces will not blow out the tail pipe. A "test pipe" will cost you performance, not to mention the effects to the air. Suck it up..time to get a new one.


Rev

Like Rev Den said. Also, the loose pieces can actually accumulate in a way that will increase back pressure and thereby lower your engine's performance.

Erik
88 Comanche

This is a very common problem with XJ/MJs with the 4.0L. I worked for an exhaust/Radiator shop. We replaced Cats and Radiators on the XJ/MJs at an alarming rate. Several a week.

Mine quit rattling when it totally plugged up. I could still drive almost 20 mph with it plugged but it fried the vacuum device that helps control the EGR valve. Just get a new one. Goes for about $60 for a direct fit unit from rockauto.com

Well, I am 700 miles from home and need to get the truck back up north. I can't find a converter in stock anywhere. If I do the test-pipe route as a temporary fix, will it throw a check engine light?

Will the test pipe need a bung?

I am in "get the truck home safely mode"...............

tnomud said:

Well, I am 700 miles from home and need to get the truck back up north. I can't find a converter in stock anywhere. If I do the test-pipe route as a temporary fix, will it throw a check engine light?

Will the test pipe need a bung?

I am in "get the truck home safely mode"...............

Click to expand...

If you have a 96' it should have a 2nd o2 sensor in the CAT. If you went the test pipe route, by the time you had the pipe cut and hole for the bung you would be at the cost of new CAT. Even with that it will most likely throw a check engine light.

I would just get the CAT locally where you are and replace it. I found one at advance auto for 80.00 bucks. Here is the link to it.

http://www.partsamerica.com/PartDet...MAR&MfrPartNumber=650584&PartType=145&PTSet=A

I can't find one locally or get one here locally for a fair price soon. Looks like I am gutting it to get this pile of $hit back on the road.

Has anyone here ever gutted an OBD2 Cat?


I have gutted them on other cars with no probelms before, but most were OBD1.

i gutted my cat a while back when i had the same problem. took off the rest of the exhuast i got the piece stuck in the hole and drilled it into little chunks. then i drove up a pretty steep incline and blew it out at high rpms. that was a temporary fix till i got another from some jeep website...it sounded like a deisel for a while (i forget the name)

small pederson said:

i gutted my cat a while back when i had the same problem. took off the rest of the exhuast i got the piece stuck in the hole and drilled it into little chunks. then i drove up a pretty steep incline and blew it out at high rpms. that was a temporary fix till i got another from some jeep website...it sounded like a deisel for a while (i forget the name)

Click to expand...

Did you completely gut it out?

Did it throw a check engine light?

I have gutted a few cats over the years (on my road race cars). VW's were very hard (took hours with an air chisel) and my Nissan came out with two hits and hand tools. What can I expect from the Jeep CAT?

tnomud said:

Ok, this weeks problem is the cat. converter.

It is rattling from the inside. Is this easy to gut out? Has anyone made a test pipe? Will it eventually just blow all the pieces out the tail pipe?

Click to expand...

What year is your cherokee, and how many miles are on it, on my 95 the catalytic converter is covered under warranty for something like 80 miles or 8 years. It was replaced around 75K along with the pipe between the header and the cat, I can't remember if I had to pay for the pipe or not, but the converter was the expensive part.

I just grabbed the OEM waranty book, at least in 1995 there was a Federal Emissions Warranty that covers your Catalytic Converter, On-board Diagnostics Connector, Powertrain Control Module, and Malfunctioning Indicator Light (Check Engine Light) for 8 years, or 80,000 miles whichever comes first.

It's a 96 and just flipped 110K, I think I am out of luck.

UPDATE: Well, we took it to my friends shop and gutted that thing out.

Before gutting it, we ran it on the dyno and ran the 5 gas analyzer in the tail pipe. The laptop battery died on the 2nd pull, butit did save the readings. The 5 gas was recorded and checked manually, it had identical readouts with and without the cat. I also got 14 MPG on the way to the shop (60 miles), filled up, and got 21.1 MPG on the way back.

The cat was cake to pound out, took 10 minutes. No check engine lights after 60 miles and the truck was noticably faster. It is not any lounder with my stock exhaust.

The entire core of the converter was simply loose in the housing. There were no broken pieces insideor clogged parts. It just slid around inside the casing.

I will post dyno numbers tomorrow morning when whe retrieve it from the laptop.