Need Exhaust Help / Opinions Jeep 4.0.

[SwampSurvivor]

So, this happened the other day:

Lost everything after the crossover. Appears the hanger before the rear axle snapped off. Whoever installed the 3rd catalyst (I do not believe it is factory) didn't crimp it enough and it fell off.

So pulled it apart on the trail and let it cool down before throwing it in the Jeep.

I figure since I have it all apart and the muffler is pretty well whipped ... I'm going to replace the muffler.

Currently:

• No issues with backpressure (if you believe in that) - it has strategic "crush" bends in the manifold and remaining crossover tube
• No check engine light - the two cats on the manifold have the oxygen sensors
• Sounds awesome!

I am going to be putting the exhaust back on for a few reasons

• I WILL NOT run it permanently without the 3rd cat. It's there for a reason. It gets 14MPG and hurts the environment enough. Catalysts are one "greenie" thing I believe in.
• It drones and hurts my ears with the exhaust ending under the passenger seat. It is much quieter from the outside. So, outside noise is okay, inside noise is not
• Fills the cabin with fumes. I was offroading all day Saturday and sunday with the windows down. Wasn't too bad. On the highway it really sucks in the fumes.

I just want a cheap, quick fix. Maybe keep it a bit louder. I was considering just buying a 24'' 2.5'' tube and straightpiping it ... but that wouldn't be too nice for others.

I can run over to advance and get a 24'' glasspack for $20. I can also get various mufflers for MUCH cheaper online than I can locally - saving way more than $20.

Anyone have any thoughts on what I should run long term?

For now I think I am going to go with a glasspack just so I can quickly get a new muffler on and weld together the old hanger.

Any thoughts on flowmasters? Or a cheap thrush muffler?

 

[hansj3]

Just weld that one back into place... $30 and you are done

However I put a thrush welded on my zj and it sounds good

 

[SwampSurvivor]

The picture doesn't show it since it isn't upside down, but the muffler is trash. It's taken wayyyyyyyyyyyyy too many rock and stump hits. Sounds like garbage and is coming apart. The baffles are broken and it rattles.

 

[eljefino]

If you want a cheap, flowing muffler from advance look at the Thrush Turbo. Coupon codes work, etc etc. IDK if it's a "pure" glasspack or has some baffles. I throw them on beater trucks.

 

[SwampSurvivor]

I found a Thrush Turbo 17696 that has the right inlet and it is offset. It's a few inches short but should be able to make it work.

Only $31 and available for immediate pick up. I think that is what I may go with.

Thanks for the suggestion! I washed the mud off the bottom of the Jeep so I can get under it and see what's going on with the hanger.

 

[440Magnum]

That catalyst is stock. Up to '99 model year it was the ONLY catcon. Then in 2000 they ditched the tubular header that 4.0s had always had since the HO days and went to the [censored] cast iron exhaust manifold with two pre-cats which raised under-hood temps even higher. They kept the main cat where it was and made it a little smaller than prior years. My '99 catcon is about 3" longer than the one on my 01, but the '99 doesn't have the two pre-cats.

 

[SwampSurvivor]

That makes sense. I know the older Cherokees have the catalyst there and only there.

I'm glad that it doesn't have an oxygen sensor. It wouldn't have been fun ripping that out when the exhaust fell off.

In a way, I wish mine didn't have the CA emissions package ... having the thing sputter on hot restart on a warm day and setting the check engine light isn't really that fun.

Well, it doesn't seem to do it with the back of the hood shimmed and ethanol free gas.

 

[440Magnum]

Originally Posted By: Miller88
That makes sense. I know the older Cherokees have the catalyst there and only there.

I'm glad that it doesn't have an oxygen sensor. It wouldn't have been fun ripping that out when the exhaust fell off.

In a way, I wish mine didn't have the CA emissions package ... having the thing sputter on hot restart on a warm day and setting the check engine light isn't really that fun.

Well, it doesn't seem to do it with the back of the hood shimmed and ethanol free gas.


My 01 was prone to that, and it wasn't a CA emissions car. Its the iron manifold and 2 catcons sitting a few inches under the intake manifold and fuel rail that does it. I wrapped the fuel rail in header insulation and that helped a little. There's a TSB for "vapor lock" that basically does the same thing, plus extra insulation over the #2 fuel injector. The irony is that mine always had vapor lock problems in WINTER (warm days + winter gas) whereas it never even flinched in 110 ambient temps on summer gas. Same is true for my old carbureted cars, also. Winter blend fuel should be relegated to history- it may have made sense with low-pressure TBI and even carbs in the 80s, but now it just increases pollution and ground-level ozone because of the higher evap rate.

 

[SwampSurvivor]

A friend of mine had a 2000 that originally came from Alaska and it didn't have the cats in the manifold. That would have been a cool one to have.

I have noticed the winter blend makes it worse. It'll actually start sputtering if I let it idle on the first warm day we have.

 

[Dyusik]

Cherry bomb with the sock pipe behind it. Gives it a rumble without being overly loud and annoying. Did a 0.25 oversize for cat and cb for (hopeful) imprpved flow through the cat. Cost me some 95 bucks iirc.

 

[Nick1994]

Yeah my grandpa's 96' only has 1 cat.

I know a guy with a 94' that had the cat replaced buy a muffler shop and they put the wrong one on and it wouldn't pass emissions, until they put the right cat on there. If you're getting a new car make sure it's the right one.

As for a muffler, I would just get a plain generic muffler, I personally hate the droning a lot of louder mufflers make.

 

[SwampSurvivor]

Bought the thrush turbo muffler. Took a look underneath and 99% of the stock hanger is still there. Will weld a new exhaust clamp to it when I bolt the muffler back in place!


Originally Posted By: Nick1994
Yeah my grandpa's 96' only has 1 cat.

I know a guy with a 94' that had the cat replaced buy a muffler shop and they put the wrong one on and it wouldn't pass emissions, until they put the right cat on there. If you're getting a new car make sure it's the right one.

As for a muffler, I would just get a plain generic muffler, I personally hate the droning a lot of louder mufflers make.


We do the plug test here, so no sniffing test. This cat doesn't have a sensor on it so I'd be good if I didn't put it back on. I will put it back on, though.


Originally Posted By: Dyusik
Cherry bomb with the sock pipe behind it. Gives it a rumble without being overly loud and annoying. Did a 0.25 oversize for cat and cb for (hopeful) imprpved flow through the cat. Cost me some 95 bucks iirc.


It'd dump under the cabin. I don't want to kill brain cells!

 

[slacktide_bitog]

I'd get a Walker cat and a Dynomax catback part #17340. Walker/Dynomax products are good quality.

 

[Dyusik]

Originally Posted By: Dyusik
Cherry bomb with the sock pipe behind it. Gives it a rumble without being overly loud and annoying. Did a 0.25 oversize for cat and cb for (hopeful) imprpved flow through the cat. Cost me some 95 bucks iirc.


IIt'd dump under the cabin. I don't want to kill brain cells! [/quote]

No leaks, and no issues with emissions testing.

 

[artificialist]

I'm not sure what cat to use, but I had a great setup when I had my Saturn.

I had the longest Magnaflow glasspack style muffler that would fit, then had a Dynomax Super Turbo muffler at the end. I had more horsepower than stock and the car wasn't louder than stock.

As for a catalytic converter, there are numerous cheap ones, but they typically contain so little precious metal, that they hardly have a purpose.

 

[jeepman3071]

Dynomax super-turbo cat-back exhaust.

This is coming from someone who has changed the exhaust on his Jeep and friends' Jeeps many times.

The loud exhausts sound cool for a day, maybe even a few months, but soon they will give you a headache. Dumping the exhaust under the cab makes it sound broken. Everything inside will start rattling after awhile, and holding conversations inside the vehicle will be difficult.

The Dynomax kit is so easy to bolt on its laughable, and it has the perfect sound. It has a bit deeper tone than stock, while retaining the stock volume so it isn't annoying. I've had mine for 40k miles now and it still looks good. I painted it with high heat paint before installing it. I also gained some seat of the pants acceleration and about 1 mpg.


For cats check out performance-curve.com. They have the cheapest prices around on quality cat converters.

 

[Jarlaxle]

Dynomax is $149 from Summit[. There's a mail-in rebate if you order before the end of June.

 

[rslifkin]

Originally Posted By: 440Magnum
Winter blend fuel should be relegated to history- it may have made sense with low-pressure TBI and even carbs in the 80s, but now it just increases pollution and ground-level ozone because of the higher evap rate.


I dunno about that... My Jeep starts like a champ in pretty much any weather, with only one exception. If I'm traveling during the early spring and pick up a tank of summer blend in a warmer area and then head somewhere cold, it'll start fine warm, but let it cool down overnight and it'll crank for 7 - 10 seconds before starting to fire at all, and then it's another second or 2 of stuttering and running on a couple cylinders before you can let off the starter without it dying (until you refill the tank with winter blend, then it's fine).