Eagle

More power and torque in a 2.5L? One word: "Cam"

Thoughts: (1) It almost certainly doesn't have an AX-15 transmission, because Jeep didn't start using that until mid-1989, and it only fits the 4.0L. Your son may have an AX-5. (2) Jeep wasn't using the 231 transfer case in 1986, either. You probably have an NP 207. (3) Do NOT try to bore out a 2.8L to 3.4L. You may or may not be able to bore it that much, but the later 3.4L engines had MANY improvements over the 2.8L, and just boring out a 2.8L won't get you any of them.

That's always a good place to start. It also helps the parking brake to work (a little).

Sorry -- not possible. First, unless you get VERY lucky and find a Comanche in a junkyard with a heavy-duty axle, more than likely you'll be getting an axle from a Cherokee. The Comanche is spring under axle (SUA) and the Cherokee is spring over axle (SOA). Also, the distance apart for the spring perches is slightly different for the Cherokee. So there's basically no way to avoid welding spring perches (unless you luck into a Comanche Dana 44). Second, both the Dana 44 and the Chrysler 8-1/4 are about 1-inch longer than the Dana 35, so to use either (at stock height) you will probably have to get the driveshaft shortened.

"Tiny" doesn't tell us anything. What size are they, and what load range are they?

It very well could be the proportioning valve. The XJ proportioning valve is built into the distribution block under the master cylinder. The circuit feeding the rear brakes goes through the front end of the block. Inside, there's a plunger with an O-ring and a very strong spring. Under light braking, there isn't enough pressure to move the spring, so the plunger keeps the rear blocked and the front brakes do all the work. In theory, under heavy braking, there's enough pressure to overcome the spring, moving the plunger and opening the circuit to the rear brakes. My '88 XJ hasn't had any rear brakes for about four years -- I've tested it on snow and ice. NO rear brakes. What I think happens is that, because the rear brakes normally don't get used, the plunger in the proportioning valve gets gummed up, and then when you need it it can't move. I keep meaning to remove the plug from the nose of the proportioning valve and clean it out, but I don't drive the '88 much any more so it hasn't been a priority.

As I and others have pointed out, a Comanche with Metric Ton springs has a payload of 2200 pounds with no need for special wheels or tires, so that takes care of your 1500 wish list.. Use standard Jeep wheels, go to Wal-Mart, and get a set of the original Wrangler Radials for $88 per tire. The ony size available these days is 235R75-15, which is one size larger than the largest tire offered from the factory but which is (IMH) a perfect tire size for a street XJ or MJ. No upgrades to the frame are necessary. As others have pointed out, to tow a heavy trailer you do need heavy-duty cooling and you should have a heavy-duty axle. In the days of the XJ and MJ, the oprional heavy-duty axle was the AMC Model 20 in 1986, and the Dana 44 after that. The '97 and newer Chrysler 8-1/4 is just about equal to the Dana 44 in strength, so that's also a possibility. First, you need to know what axle you have. Post a photo of the rear differential.

It's an '88, which means it is essentially an AMC even if it was built after Chrysler bought AMC. AMC was notorious for over-boosting their power steering. It's characteristic of the breed. I've always been an MC owner (since before they were AMC) so it doesn't surprise me, but it always bothered me. In my Javelins and AMXs I ran quick ratio manual boxes because I couldn't stand the power steering. My early XJs and MJs all have too-light steering and basically no road feel, but I've never felt like spending the money to have a box rebuilt with a stiffer spool valve.

??? With metric ton springs the payload is 2200 pounds. Of course, the Dana 35 axle may not stand up to that too long. You need either an XJ or MJ Dana 44, an MJ AMC Model 20, or a 97 or newer Chrysler 8-1/4 out of an XJ. The Chrysler axle would be my last choice because of the puny 9" brakes, but it's also probably the easiest to find. I don't think you should even consider bumping the payload over 2200 pounds. The frame won't be happy.

One more time: That tank on your firewall is not -- repeat NOT -- an overflow tank. It is a part of the pressurized cooling system. The '87 - '90 4.0L MJs do not have any cooling system overflow. They have a closed system. The cap of that tank is the pressure cap. The tank is an expansion tank, and must be filled only to the halfway mark when cold.

I did the timing chain on my '88 XJ 4.0L around 200,000 because I remembered that the older AMC V8s used nylon teeth on the large sprocket and I was afraid mine was probably about worn out. In fact, it was as good as new -- virtually no slack at all. I put the new timing set in as long as I had the engine open, but I still have the old parts and I wouldn't hesitate to install them in a beater engine. I'm familiar with double roller timing chains, but I've never heard the term "double braced."

??? What's a triple braced link? The parts in your photos look like the OEM parts, and they look like every 4.0L timing chain set I've ever seen.

Yep. No need to have two threads on the same topic.

Why? Unless you are going to run huge tires and you frequently get really crazy with the gas peddle, the dana 30 is all you'll need. How about a photo of the rear axle? If the seller lied about the front, he may have lied about the rear as well.

^^^ This.

I was leaning in that direction, too. I can't think of anything else that would do it.

I currently own three: a 1987 Pioneer, a 1988 SporTruck, and a 1988 Chief. IIRC I've had four more pass through here since the addiction took hold.

Interesting, but hardly a Jeep. Translation (very rough) of the description: "It based on the French vehicle Overland A-3, was designed for Eike cambric (better known in Brazil as the husband of the model Luma de Oliveira) to replace to the old jeep Ford CJ5. Due to the good fulfillments of the French Overland, its designer decided not innovate too much but to trust in the reliability from the A-3 and to utilize the same platform. Its greater characteristic is that of utilizing common components with many other vehicles of the Brazilian market, facilitating the logistics. They were manufactured 500 in their military version since 1994 to the closing of the factory, in 2001." Outside of the U.S., as I learned when I first visited Chile in 2003 by invitation from a Chilean member of NAXJA, anything and everything that is remotely a 4x4 SUV is thought of and referred to as a "Jeep." While I was there I went on an expedition to the sand dunes with my friend's 4x4 club. We were out in the middle of a sea of sand, waiting for other members of his club to show up. We heard an engine in the distance and Mike (Miguel) said, "Ah, here comes Ivan in my old Jeep." And a minute later what popped over the top of a dune but a Daihatsu Rocky! To them, it was a "Jeep."

Looks good to go. I was going to point out that I believe the length of the rod is different, but this kit solves that by using a shift arm with multiple holes. Plus it's just threaded rod, so if necessary you can go to any Lowe's or Home Depot and buy a length of all thread.

Well, it's try to build up pressure. But ... as dainternetguy wrote, liquids don't compress. So if the bottle is full and the pressure increases, there's only one thing that can happen -- the cap fails and the pressure vents through it. The owner's manual and the FSM say to fill it halfway. That's why there's a post inside -- it's marked to show you how far to fill it.

I wasn't aware that this product exists, but it looks like a good product, and it certainly looks like the solution to your problem.

I believe it's a proprietary (factory) hose with one end expanded larger than the hose body. Don't remember for certain. Check NAPA. BTW, on your Jeep that is not an overflow tank. It's a pressurized part of the cooling system. When you get the new tank, do NOT fill it all the way up. It should be filled to the halfway mark when cold. No higher.

In general, the synthetics like Royal Purple are safe for the synchronizers. The Pennzoil Syncromesh was formulated specifically for transmissions, so it's also a pretty safe bet.

Much will depend on whether any water gets into the car. If so, you'll need to strip out the nterior and dry it out.

I believe NAPA has the tank. Possibly Quadratec, too, but I'm not at all sure about that.