Please see my update at the bottom of this article. I had some issues with the belt keeping all 6-ribs, so I gave up and ordered the correct OEM parts to complete this swap.
So I've had in the FAQ for a while, and its mentioned in various places that the WJ intake is worth some horsepower on the older motors. This intake was found on 99-up WJs. Below is the standard "old" style YJ/XJ/TJ intake compared to the WJ intake. Pretty evident why it's worth some power.
After doing this swap, pretty much blindly because there weren't any writeups I could find, I figured I'd do a writeup. It will go onto the older style 4.0s with some minor modifications.
The largest hurdle is the mounting of the power steering pump bracket. The WJ (and newer style 4.0s) use a different mounting pattern and depth than the older 4.0s. First you need to bolt the bracket to the bottom hole in the water pump (Just like factory). Then make two small brackets to relocate the pump. If you notice in the picture below all I have is two pieces of flat plate with small bends in them with two holes drilled in them.
Now because the power steering pump will be relocated the belt ends up needed re-routed. Notice the missing bolt in the image below. Its the top bolt in the belt adjustment, the lower bolt and the one that goes in from the bottom is still there. I tried using a bolt that ground the head down, but the belt must have just barely hit it on day 2 and it shredded the belt, so I took it out to eliminate the chance of this happening (To be fair I forgot to tighten down the power steering pump, so it could have moved. I just chose to eliminate all possible chances of another belt being destroyed). There are still several bolts holding everything together, in my opinion it wasn't necessary to have that bolt.
Next because of the change of the location of the power steering pump and the angle it's not at you will lose most of your adjustment. The pump will still move the full amount of travel, but due to the angle it's not adjust much by moving it. So the belt must be almost exactly the correct size. This is what I found the best routing option for the belt to be after relocationg the power steering pump.
This routing unfortunately places three smooth pulleys in a row, and requires the grooved side of the belt to ride on a smooth pulley. If you use the factory pulleys I found 744K6 belt worked perfectly. However I chose to switch to a grooved pulley for the top idler to help keep the belt located, and so the grooved side of the belt wasn't riding on a smooth pulley. I used Gates idler pulley 36320. This will bolt right on using the factory bolt and bushing, I did however need a single 3/8" washer to space the pulley out. This pulley is slightly smaller though, which meant I had to switch to a 735K6 belt. The Gates pulley will be metal, other manufacturers may be plastic.
The Gates pulley at the top there. Notice it's a 7-rib pulley, but works perfect.
As for the final part of the install, almost everything will swap over. Since I needed a return line I had to use my factory YJ fuel rail. The throttle body is the same on the WJ and YJ except for a few minor differences. The WJ one does have a vacuum port on it. You can use either. You can also interchange the IAC and TPS sensors, so you can transfer over your YJ sensors to use the factory plugs. The IAT can also be relocated to a back port so your factory wiring will reach. Other than that I just plugged off the additional ports, as most were not used in my application.
This intake will work either both new and old style exhausts. It will work fine with the early 4.0 intake gaskets as well.
So it's been a while since I installed a WJ intake in my YJ, and it's time to do the install the "right" way. So I want to list the parts and such that are needed to do this correctly.
The power steering pump mounts differently, on the WJ (and newer TJs). To get things correct on a YJ you need to update to the newer style tensioner. The parts below are what you need for the WJ intake.
33002201 - Bushing
06503230 - Spacer
06503198 - Bolt
34202029 - Bolt
53010149 - Sleeve
53010148 - Bracket
04792112 - Pulley (This is available from the auto parts store, but my local dealer was the same price.)
You should end up with this setup from the parts list above:
On top of the parts above, you will also need these things from the local auto parts store / hardware store:
Parts Store / Hardware Store
685K6 - Belt
300-310 - Power steering pulley (requires special tool to install/remove, can be rented from auto parts store)
M8x1.25 x 100mm Bolt - 2
I have no idea why I put this off for so long. Everything went together pretty easily. You will need to remove the power steering pump from the Jeep entirely. Odds are pretty high you may be buying new hoses as you may destroy them removing them. Luckily it's only another $30 for the pair ($21 / $9 locally). Once the pump is off, you need to drill out the threads on the two of the holes.
The holes do not need to be sloppy, you just need to be able to slide the M8 bolts you purchased through the holes. These two holes will mount the pump to the intake. The reason you need the newer style power steering pulley is because of the holes. These holes allow you to bolt everything together with the pulley in place. After you have drilled the threads out of the two holes, install the new pulley.
The entire point of doing this was my Jeep kept eating a rib or two off the belt, then it would be fine. So clearly something wasn't right. With this in mind, I decided to also bypass the pulley I added that was not OEM (I mention using a washer to space it out in my original writeup).
For this I found a 685K6 belt to be a great fit, with the routing below:
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