Teloca

I have what apprears to be a small crack in my exhaust manifold but I don't think it is leaking. I was going to replace it with a header but it looks like you have to take the intake maniflod off. How difficult is it to do...any tricks that I shoudl be aware of?

Anybody have thoughts on a good header that's not too expensive but will improve performance.

Also has anybody had any luck gettting a high-flow cat from a salvage yard? Thoughts on what to get it off of?

Gee oh Dee

Pace setter makes a good one.

99bluexj

I'm in the same boat. I'm in the process of replacing my exhaust system from the manifold back. I was only planning on replacing the cat and everything back from there, but in the process discovered a large dent on my intermediate pipe right below the manifold. Not sure how that got there but I figured I better replace that pipe too while I'm at it. Then I noticed the inevitable crack developing in the manifold too. I don't think it is leaking yet but am wondering if I should do it now since I already have the rest of the exhaust detached. Unfortunately, my service manual for the '99 lists 17 steps to remove the manifold and 22 to reinstall. After having read through it, I'll admit I'm a bit intimidated. I have no formal training and typically learn by doing, but generally do handle most of the work on my Jeep. I'm just not sure about this job though and would be interested in hearing what some of the veterans have to say about it.

142XJ

It's really not that big of a deal to take off... Yes you have to take off the intake manifold as well since if you looked at it you noticed they share bolts. You'll have to crawl under the Jeep to reach a few of the bolts and the rear ones are a pain but its nothing impossible. Having to pull the intake is just a good excuse to clean it. You'll have to pull a bunch of vac lines and unplug some sensors too. I can pull the intake/exhaust manifold and the air box and have everything reassembled in about 2 hours. Just grab a wrench and get busy. There's not much that can go wrong. You might need to buy a new exhaust manifold and intake manifold gasket after you take the old one off. Should be around $12....

As far as a good header goes.... Your money would be better put to use in other applications. Just weld up that developing crack real good and put it back together. Ditch the cat (unless you'll have to smog in the foreseeable future) and run the best flowing muffler you can find. There's flow charts redly available online. Personally I'm a big fan of Spintec mufflers. I run the stock header to a 2.5" pipe with a Spintec then more 2.5" all the way out the back. That in addition to a 9" cone filter for a cold air intake makes for a great combo. I have no complaints. Still have plenty of low end torque and I can pull just about any hill on the freeway in 5th gear while maintaining 65mph with 31's and 3.07 gears.

I'm on my 5th Cherokee right now (4th with the 4.0) and all my exhaust manifolds have cracked. After welding the crack back together they never cracked anywhere else.

99bluexj

Ha. Just discovered that the dent in my intermediate pipe is factory. Odd, but I guess it is what it is so I'll just reinstall it.

Here's a good article that might be helpful. http://www.off-roadweb.com/tech/0610...all/index.html

Holliday79navy

Never replaced an exhaust on an XJ myself, but remember, those manuals will assume you are an idiot. Check it out, look for the obvious stuff that would get in the way, see if there is anything critical in the manual, then get at it. Should be able to do it no problem other than various bolts seizing up, which is my guess for the most problems.

Teloca

I am told the "dent" in the pipe (about 8" below the flange) is standard. I was told by a muffle guy that it was there to keep the drive shaft from hitting on the stock suspensions, but is not an issue if you have a lift. Don't know if that is true but I intend to replace the dent as well.

SoonerEd

Been thinking about replacing my exhaust manafold as well. Been hesitant as my 99 spent the first 3 years of its life in the salt winters of NJ. Seems like everytime I try to work on something the bolts are seized, rusted, round off, break, etc.

How bad are the bolts into the block on seizing and breaking off. this has been my biggest worry in tacking the job. Had them break on small block chevys and its sucks.