Eagle

I have always used sealant on freeze plugs. Nothing high-tech -- good, old-fashioned Permatex Aviation-Grade Form-a-Gasket.

Time to clean up the yard. There are too many hulks out there, and I expect the zoning enforcement officer to pay a visit any day. I'm not interested in getting into parting out the XJs on a formal basis. The reason they are here long since expired, so it's time to clean house. I've got a local yard that will pay me $75 each if they're complete, or they'll take them for free if I remove any significant parts. I'm sure they don't care about small parts. So ... who needs something that I might have? The two that are going are an '86 Pioneer 4-cylinder 5-speed (4WD) and an '89 Pioneer 4.0L automatic (4WD). Send me a PM if you need something that might still be on them.

Yep. And you can run a rough test of it by having someone watch the timing mark with the engine running, and have another person tap the block next to the sensor with a hammer. If the timing jumps, the sensor is working.

That is not what he said. Rather, the renix engine has a knock sensor that permits the ecu to advance ignition timing to the point where the engine knocks, then backs the timiing off. Eagle put a high altitude Crankshaft position sensor on his truck. The high alltitude CPS has a wider range of ignition advance than the normal CPS (octane requirement drops with altitude because altitude has the same effect as lower compression). So because of the High Altitude CPS and the high octane fuel, his ecu advanced the timing further than normal which improved the highway MPG. Without the High Altitude CPS, premium fuel would have done nothing at all for the MPG. That IS what I said. Back in 1988 and 1989, I didn't know about the high altitude CPS, and I wouldn't have bothered replacing the original with one until it failed anyway. Just running high test fuel should result in an increase in mileage -- IF you have a light foot, so the engine isn't spending a lot of time under load so the knock sensor has to keep retarding the ignition. The high altitude knock sensor should make more of a difference, but the difference is there without it. It does this because with the higher octane that reduces knock (ping, pre-ignition) the knock sensor doesn't retard the ignition as much or as far.

It should increase your gas mileage -- more if you run a high-altitude CPS. But only for the Renix years -- the HOs don't have a knock sensor. The real question is whether it will increase the mileage enough to offset the higher price of the fuel.

On the flip side of anecdotes, if you have a Renix with the knock sensor, then there IS a benefit to running high test -- if you run it all the time and don't have a lead foot. When my '88 XJ was new, I ran high test all the time. My highway fuel mileage was phenomenal -- like 28 MPG on a road trip from Connecticut to Vermont, loaded down for a weekend with a lady friend, her daughter and a friend of the daughter, clothing for a winter weekend in Vermont, and "stuff" to keep the two kids occupied for a weekend. Why? Because the Renix advances the spark as far as it can, then backs it off when the knock sensor detects ping. High test reduces ping, so at cruise throttle I was running with more advance than would have been possible on regular grade fuel.

No.

In your opening post you said you didn't have a welder. Then you wrote: Make up your mind. Modifying a truck for off-road gets expensive VERY fast. You're currently on 32" tires. Then you started asking about 35" tires. You don't need 35" tires for the type of off-roading you described. In fact, you don't even need 32" tires for that -- you could do it on stock-size tires with no lift. When Paragon was operating in Pennsylvania I ran just about every trail they had in a shortbed MJ on 31" tires with a basic Trailmaster 4" lift, and I could have run most of them just as easily with no lift. (I know, because I also ran most of them in a Cherokee on 30" tires with no lift.) The direct answer to your original question is that ONLY a Dana 44 from an MJ will bolt into an MJ. An XJ Dana 44 is the same width, but the spring perches are in the wrong location and have to be cut off and relocated, or you buy new perches and weld those on. Next choice (IMHO) is the Chrysler 8.25 axle from an XJ or maybe a Liberty. You want one from an '97 or newer, to get the larger, 29-spline shafts. The axle width is correct but, like the XJ D44, you have to relocate the spring perches. After that (IMHO) comes the Ford 8.8 axle. It's a tough axle, they're cheap, many have a limited slip already in them, and the newer ones have disk brakes. They are also too narrow. You WILL need to budget for buying spacers, or aftermarket wheels with a lot less backspacing than factory. The problem with using the wheels to fix the axle width is that if you run the same wheels in front -- they stick out too far. I think you need to sit back, take a deep breath, and reexamine your budget and your priorities. Then come back and tell us what you can realistically afford, and we'll try to help.

What size are they? Can't tell from the image. Does the text run the full width of a rear window, or just occupy a corner?

Both the Renix and HO 4.0L engines in the XJ and the MJ use a 2-1/2" down pipe. The catalytic converters are 2-1/2" all the way through, and the converter tailpipe necks down from 2-1/2" to 2-1/4" between the cat body and the muffler inlet.

You beat me to it. Are those the ones with three locating holes? That's what I was thinking of but I didn't know who makes them.

$125 plus the price of a pair of Spyderco spacers (plus shipping).

The AMC 2.5L uses the same small bellhousing bolt pattern as the GM 2.8L and 3.4L V6s. The AX-15 bellhousing won't mate to that block. Dodge used the AX-15 behind the 2.5L for a few years in the Dakota pickup. You'll need a Dakota bellhousing to make it work.

Both are good rules. The first, especially -- many other wise people also advise never lifting more than you absolutely need to. The corollary is that the price of lifting increases exponentially with the height of the lift (in other words, twice the height costs four times as much).

How many miles on the engine? I have an '88 2.5L that runs okay, but at 209,000 miles it's pretty tired.

As noted, the shortbed tank is different from the longbed tank, so be sure to order the correct size for your chassis. New tanks may come with the locking ring (I don't remember if the new tank for my '87 did), but they won't come with a new gasket. Be sure to buy a new gasket (it's a big O-ring). In fact, buy two, because you may tear one up trying to seat the lock ring. Before buying a new tank, check carefully to be certain that the leak isn't where the two steel lines enter the fuel pump mounting flange. I made that mistake. Bought the new tank, installed it, drove to the gas station to fill up -- and saw gas running across the concrete when it got to about 3/4 full.

Disk brakes are less of an advantage when crawling trails than they are when racing. I'm not crying my eyes out at night because none of my XJs or MJs have rear disk brakes. Offsetting the possible advantage of the 8.8 having disk brakes is the fact that it's narrower than the XJ/MJ axles, so to run even stock tires on stock rims you need spacers. The XJ 8.25 is already the correct width, so just flip the perches to where you want them and you're done.

Go with the XJ axle -- IF it's an 8.25. My understanding is that the late-model XJs used the 8.25 if they did NOT have ABS, but the ABS vehicles still used the Dana 35. I've never seen an XJ with ABS up close and personal, so I can't verify that.

The problem is that the 4.0L transmission has a larger bellhousing than the 2.5L transmission, so you can't attach the '95 transmission to your engine. BUT ... When Chrysler was using the AMC 2.5L engine in Dakota pickups, they used it with the same AX-15 transmission as your '95 XJ. So what you would need to do the swap you have in mind is a bellhousing from a 2.5L Dakota. Oh, and you'll almost certainly have to have the length of your driveshaft altered.

Personally, I would rather buy a motor from a junkyard. My thinking is that someone started working on this, and then for some reason they stopped. WHY? Is it cracked? Are the cylinders scored (maybe not a problem since you would be replacing pistons anyway, but depends on how badly scored.) Are the cylinders out of round? (Again, maybe not a problem if you'll be boring for new pistons, but ... how bad?)

They could not have used a clutch for a BA 10/5. The BA 10/5 clutch pressure plate and disk are too large to fit the 4-cul flywheel and bellhousing, and the slave cylinder/throwout bearing is a larger diameter.

No. The link is to an ad for a Renix 4.0L block. To make that into a stoker, he'll still need to source a 258 crank, plus rods and pistons.

Dunno. There are subtle differences. If you have keys to an AMC-era XJ or MJ, compare the ignition key to the door key. Aside from the shape of the head, the actual key part is slightly different. I don't remember which way it works, but IIRC either the ignition key will go into the door locks but the door key won't go into the ignition -- or t'other way around. I'm not talking about operating the locks -- just putting the key into the cylinder. So they ARE different.

But they're not. The ignition cylinders are basically GM cylinders, but pre-AMC their predecessor, Hudson, used Briggs and Stratton keys, and AMC continued to use the same keyway even after the shape of the key head changed. As for cutting off at 1984, that's not correct. My 1988 Cherokee was bought new, delivered in January of 1988, and the keys are AMC keys.

Would it work? Depends on what you mean by "work." You'd be buying a block for $100. Seller says it has "supposedly" been gone through, which means somebody sprayed it with degreaser and a quick shot of ugly yellow Wal-Mart spray paint.