Exhaust and convertor suggestions

[teeje]

I have a 2002 Jeep Liberty. I had a brand new engine installed about 2800 miles ago. Ever since then I noticed a small leak after the manifolds. The muffler was shot so I got a glasspack and welded it. I can still hear a small leak and although the glasspack sounds nice, I'm tired of the drone it creates in the cabin.
I want to replace the cats and muffler altogether. Mind you I'm in college so I can't spend more than 500$
I plan on doing it in a couple months so I'd rather have suggestions until then.
If I'm correct both cats are bolted on with a flange on both sides and come as an assembly.
This is the part in speaking of

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And of course the muffler but I'm sure I don't need to post a picture of that. I also got a CEL last night for a p0421 : catalyst efficiency low
I'd like some input on that as well. I reset the light and it hasn't come back.


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[M38 Bob]

The part you've pictured is the rear, secondary converter. Honestly, your Jeep will do just as well with it completely off as on. The secondary seldom ever goes bad(and has nothing to do with codes) unless one of the primaries goes bad and pieces of it clog the secondary. O2 sensors measure both in front of and behind the primaries. Primaries bolt between the one you have pictured and the manifolds.

As expensive as cats are, why not fix the leak??? That may be all that's needed to keep the code off.

Bob


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[teeje]

Not sure where the leak is exactly. I do plan on dropping everything when it gets warmer here because the heatshields weld on the driver side cat broke when the shop put my new engine in but at least it doesn't rattle. What purpose does the second one serve? Also how easy is it to drop the primary cats? They're accessible and I have impacts for those bolts. I just don't want to dive into something and get lost. As far as the 02 sensors go, should I replace those when I replace the cats?


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[M38 Bob]

Jack it up SECURELY. crawl under there with engine running and listen/feel for leak. Replacing cats instead of fixing leak is total foolishness.

Bob


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[teeje]

Jack it up SECURELY. crawl under there with engine running and listen/feel for leak. Replacing cats instead of fixing leak is total foolishness.

Bob


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Yes jack stands and everything. I did do that I've gotten on my creeper and put my hand around the flanges (not on them obviously) and I can feel the leak. I've tried sealing it a couple times and it got better. I think the only thing I can do now is drop everything and clean everything to see exactly where the hole is.


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[M38 Bob]

Where'd you find the leak? Occasionally a flange will crack and require replacement, otherwise new gasket(where applicable), new bolts, lubricated fasteners, etc will fix most any exhaust leak. Over the years, I've often cut cracked flanges off good exhaust assemblies and replaced just the flange. Don't discount a professional muffler shop without at least checking with a couple of them.

Bob


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[teeje]

Where'd you find the leak? Occasionally a flange will crack and require replacement, otherwise new gasket(where applicable), new bolts, lubricated fasteners, etc will fix most any exhaust leak. Over the years, I've often cut cracked flanges off good exhaust assemblies and replaced just the flange. Don't discount a professional muffler shop without at least checking with a couple of them.

Bob


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I found a small hole before the flange and I sealed that with some high temp exhaust sealer. Damn me if I can remember the name. I'll have to take a picture of it. But I'll try to explain it. Right before the flange that bolts to the cats is where the leak is. Not sure if it's the flange itself where the mating surface is or not. When the shop put that new engine in, they used some high temp stuff that's red. Not sure it's high temp rtv because it's hard. Is there supposed to be a gasket between the two flanges?


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[M38 Bob]

No. Do pull apart, clean, and inspect for damage. If all's ok, no sealer should be needed,just make sure fasteners are good and lube,preferably with gold colored anti seize, then tighten em well. If there's a hole or crack, try getting estimates to have it professionally repaired.

Bob


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[teeje]

Will do. So they were wrong and cut corners when that bolted the flanges back together. What a shame. You figured you'd pay a shop to do something for you, they'd do it right. Engine is great but can't reinstall exhaust parts the right way. Wish I could've done it myself but time did not allow.
Plans in the upcoming weeks: pull apart clean everything and inspect for damage.


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[TwoBobsKJ]

Those exhaust flanges can be troublesome. There is a 'donut' gasket that is supposed to go between the cat flange and the Y-pipe of the exhaust and it's held in place with the spring bolts. That donut is hard to get in place; I can't find a proper sized one for the life of me so I use one from NAPA and cut it to size (it's too thick so I have to cut it thinner.)

Also get new spring bolts from Advance, NAPA or someplace like that as the originals rust too easily.

Bob

 

[M38 Bob]

Yea, probably cutting corners, but may have been for your benefit instead of theirs, nothing more dreaded in a shop than having to call a customer and inform them of ANOTHER unforeseen $100.. Expense.

Bob


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[teeje]

Donut gasket? Oh boy


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[TwoBobsKJ]

Donut gasket? Oh boy


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Yep - slides over the pipe on the converter and pushes up against the flange. The very end of the converter pipe slips into the Y-pipe and the flange of the Y-pipe butts up against the donut.

Here's a picture of one at AutoZone.


Bob