MtnGoat

Over the past 100k miles I've replaced cracked exhaust manifolds 4 times now. Using Stock OEMs from the stealerships, to Stainless Steel thick wall headers, to name brand header companies. Thats not what I'm writing about here. Although anyone wanting chime in with their two cents on the subject is welcome.

The job to remove the intake/exhaust manifold bolts is a real PITA. And the reassembly is worse. Fighting the intake manifold into place and installing the lower bolts in the blind is shortened with the MtnGoat Method. I found an interesting way to avoid the hassle. Once the manifolds are out a simple modification to the intake is in order. There are two dowel pin alignment lugs that need to be cut down. I used a die grinder and removed the lower half of the lug. This way the manifold can be lowered onto the pins.

So the procedure is simple. Install the gasket then the exhaust manifold onto the pins and studs. Secure these with the two end washer/nuts and the center bolt/washer. Install the LOWER four bolt/washers and turn in 1/2 turn or so as to get these bolts "started" but not to fall out. Also making sure the washers are seated against the bolt head base. Now drop the intake manifold into place, feeling for those pins & half lugs to align. Now install the remaining bolts/washers and torque as required.

This procedure recently saved me a lot of aggravation. And maybe it will help some of you too.

00t444e

It may not be the easiest of jobs to change the exhaust manifold, but the 4.0 is the easiest one I have ever changed. My 97 has 240,000 on it and spent it's whole life up here in the rust belt, and I was able to get every manifold bolt out without issue, and the bolts where still in useable condition, but I still replaced them. Generally around here if you have to change an exhaust manifold on a vehicle that's over 10 years old that means you have hours of grinding, torching, and possibly drilling ahead of you to get the old manifold bolts out due to rust, but that hasn't been the case with the 4.0s I have done.

Cummins93

This was a big problem I ran into with aftermarket headers. Some of the rear bolts where impossible to get to with anything other than a crescent wrench. When designing my turbo manifold this came to mind as there was no reason to make it if I couldn't get it torqued down. After much trial and error I managed to make a manifold with a turbo attached easier to bolt on than even the stock manifold.

On all 4.0s that I own, the back lower 2 bolts get replaced with studs, the rear most is already a stud. This makes locating them fairly easy.

cruiser54

Do this and quit replacing them over and over.

MtnGoat

I will

00t444e

I am in the process of replacing my whole exhaust, I already have a new APN header, and the front pipe installed, along with a new upstream o2 sensor. What is the best place to put that expansion joint in?

MtnGoat

I was thinking where the pipe runs under the oil pan

PatHenry

I found getting the intake on the dowels was not that hard on my 95. From below I was able to visually inspect that the rear one was on and (IIRC) I could see the front one from the engine compartment. Getting a wrench on the bolts was not that big of a deal going from underneath for the back ones with the proper length extensions.
If you're doing the whole exhaust, having the front pipe out of the way was a huge help - it made getting at the bolt super simple.

My biggest problem was that my new front pipe had the O2 bung located at a terrible angle so the sensor runs right up next to the oil pan. I put some "exhaust pipe wrap cloth stuff" on the end to keep the wires insulated from the heat of the pan and it's been running fine for a few thousand miles.

MtnGoat

The flex joint has not resolved the exhaust cracking issue. This one didn't last 6 months....

So now money is no object. Who makes the best exhaust header/manifold?

XjJunky

Just installed this header from RT Offroad. Only 300 miles on it so far so not sure about longevity. Beefy as hell and a direct drop in bolt up. 304 stainless steel including the flange. They do have a cheaper one that is 304 ss with a zinc coated flange. Also sid motor mounts and trans mounto at same time so that should help longevity of the header

Cummins93

For fun pop your hood off and drive down the road in high gear and moderate throttle. If it was anything like my experience (with new OEM style motor mounts) you will see your engine dancing around. If it does stop focusing on manifolds and more time focusing on locking that engine in place.

XjJunky

Motor mounts haven't been stock for years. Polys i had finally took a **** so i just replaced them with some nice ironman4x4 motor mounts. Yes even good poly mounts go to hell with lots of hard wheeling

Cummins93

They all wear. The difference is the stock design is a failure out of the box and are not serviceable.

XjJunky

I totally agree with you. It just baffles me that ppl would replace crap with even bigger aftermarket crap. If your jeep is a stocker then it's understandable, but it is amazing how many ppl pull the old ones out and replace them with the same thing and then are suprised when they only last a couple months ( guess they like being under there jeep more than being in your jeep on a trail). Its better to spend a bit more once and be good for a few years. After the 4 sets you replace in a couple years you have already exceeded the price of HD mounts

MtnGoat

Followup.

For what it's worth, I replaced both engine mounts two years ago. Since the drivers side mount was destroyed from heat, I wrapped the replacement with a heat reflective material.

I found a Banks header that was affordable and installed recently. They advertised that cracks are a thing of the past.

I'll remain skeptical.....