Eagle

If you plan to ditch the rear height-sensing valve, you MUST remove one of the two lines from the front. Specifically, you keep the one out of the "nose" of the front metering block, and you remove the one coming out of the bottom of the metering block and plug that outlet. This has been written up in several different threads on here. I know it's impolite to greet a new guy with "Try using SEARCH," but I don't have any of those threads bookmarked because I already know what needs to be done and how to do it. So rather than me search it for you, I'll simply recommend that you search it out. It's here, along with a lot of other useful info about MJ brakes.

If it has enough fuel pressure to start, the fuel pump works. It sounds like the ballast resistor. Simple test -- hot wire the fuel pump and see if it will run more than 30 seconds.

yeah its a crap motor. worst motor ever from GM... to my knowledge Your (lack of) age is showing, Grasshopper. GM actually did have an even worse V6 engine. I don't remember the displacement, but it was introduced in the original Buick Skylark back in the early 1960s. And, in a clear demonstration that those who do not learn from the mistakes of history are doomed to repeat them, GM sold THAT engine to Jeep, too. My brother had a CJ-5 back around 1972 that had that engine in it.

Well, this puts me in mind of two of my favorite sayings: The first, I have no idea where I heard it. "People who think they know everything are particularly annoying to those of us who do." (Best said in the inimitable voice of Jim Backus -- the millionaire from "Gilligan's Island") The second is from none other than Lucy Van Pelt, of "Peanuts" fame: "I'm perfect. I thought I made a mistake once ... but I was wrong." (Yeah, think about it. It'll come to ya!)

I concur. 150 degrees is well below the temperatire at which the ECU switches to closed-loop operation. I think it's around 165 to 175 degrees.

Yes, you could take it to the bare block. That means "block," not "block + head." To use your manifolds, you will need to use your head (or another non-HO head). To use the '98 HO manifolds, you'll need to adapt a bunch of brackets for things like the alternator and power steering pump. And you'll have to adapt your throttle body to the newer intake manifold. You will also have to tap a hole to mount the knock sensor in the block, because the HO engine doesn't use one. Dimensionally, the '98' block is the same as the '90 and will fit the chassis with no problems. But, as the saying goes, "The devil is in the details." You will find that you'll be doing a lot of adapting. It is not going to be a drop-in replacement. It all comes down to how cheap you can buy the '98 engine, how creative you are about adapting ... and how much time you can tolerate the truck not running while you figure out the conversion.

^^^ What he said, exactly. This isn't a "Jeep thing." Carburetor icing is what happens to airplanes flying at high altitude in winter. I have never heard of a carburetor heater for an automobile, and I'm old enough to go back to when chokes "knew" when to open up by a coil spring in a can, not by an electric heater element. I've owned several cars with manual chokes. I have never, EVER encountered "icing" of a carburetor in an automobile. Remember that the function of the thermostst in a car is to keep the temperature UP, not down. Some genius may have put a low-temperature thermostat in your MJ, or even removed the thermostat entirely, thinking it was a good idea. It isn't. Your first step should be to buy the correct thermostat for your engine and install it.

All your stuff? No. Many of the brackets for alternator, power steering pump, etc, are totally different between the 1990 Renix models and the 1998 Chrysler models. The ports on the head are different, so you can't (easily) swap your manifolds onto the "new" engine. The throttle body is different. The injectors are different. The flywheel is different and won't work with your CPS, but if you try to use the 1998 CPS ... it won't work with your Renix computer. Even the oil filter is different.

28-inch, actually. A 215/75R15 is 27.7" in diameter, and a 225/75R15 is 28.3" in diameter. I hooked JeepCO up with a spreadsheet that calculates RPMs and road speeds for all the available gear ratios and for tire sizes from 205/75 up through (IIRC) 33", so he's been doing his homework.

Pat is probably pretty well dialed-in with that setup. For anyone else contemplating gears and tires, I'll pass along my frame of reference: the original vehicles this engine family was designed for. I used to have, back when I was in the Army, a 1966 Rambler American. It had the original, 1-bbl carbureted version of what many years later developed into the 4.0L engine. I don't remember the tire size, but they weren't huge. My American had a 3-speed manual tranny (no overdrive), and 3.08 gears. One of the first things I did was buy a factory tachometer kit for it and install it, so I know (and still remember) the speed-to-RPM relationship. 24 MPH per 1,000 RPM. Which worked out to 60 MPH being exactly 2500 RPM. 3000 RPM got me a 72 MPH cruise, and it would run at 3000 RPM all day. With all the overdrive transmissions and such we have today, there's a tendency to think that anything over 2000 RPM is going to "burn up" the engine. Not so. I sold my American short of hitting 100,000 miles, but my brother had a '72 Gremlin with the same setup that went at least 308,000 miles with NO work inside the engine. I say "at least" because he sold it to one of the local parts stores and they used it to deliver parts. We lost track of it after 308,000 miles, but it was still going strong at that point. Back to my Rambler American -- cruising at 60 MPH/2500 RPM, I reliably pulled down 28 miles per gallon highway. The point of all this is -- don't be afraid to put in a bit more gear than what came from the factory. The factory chose the ratios to try to score well on the gummint's very artificial fuel mileage and emissions tests, not for what would be best for actually driving the vehicles in real life. On stock tires, my '88 5-speed turns about 1650 RPM at 65 MPH on the highway. That's well BELOW the torque peak of the engine, which is not optimal for anything.

Running at the same temperature (or wanting to) is not the issue. The issue is that a SBC generates more heat than a 4.0L, and has less space around it in the engine room to allow some of the heat to dissipate. I've only seen a few SBCs stuffed into Cherokees, but they ALL had cooling issues -- even the one with a custom aluminum radiator that was supposedly "guaranteed" to do the job. The '91 and newer "open" radiators (the ones with a neck for a radiator cap) have provision for an overflow bottle.

No photos. It's been years since I did one, but I have mounted a Kenwood, a Pioneer and a Panasonic in various XJs and MJs. My recollection is that each came with a mounting sleeve/bracket that fit into the dash, and then the radio slid into the bracket. IIRC, two of the three fit with no alterations to the factory dash bezel, and one of them (the Kenwood?) required filing the opening about 1/16" on one side to allow it to fit over the radio faceplate.

DOT 3 and DOT 4 is glycol-based. I don't think that's a veggie oil, but I'm not a chemist, so I don't know. It is physically impossible to "mix" silicone brake fluid with glycol-based brake fluid. The operative word for mixing two fluids is "miscible," and the two types ain't miscible. It's like pouring oil into a glass of water. Shake it up enough and you'll get globules of oil dispersed throughout the water, but they aren't "mixed" and, if you let it settle, eventually the oil all floats to the top in a separate layer. Same with DOT 5 and the glycol brake fluids. There is no chemical reaction. You can fill a small container partially with DOT 3 and/or DOT 4 and then pour some DOT 5 into the glass. Nothing will happen. Come back after letting it sit for an hour, and it'll be completely stratified. But, any time there's glycol fluid in the system, that fluid is hygroscopic (attracts and holds moisture vapor), and one of the primary reasons for using silicone is that it is NOT hygroscopic. So combining (I won't say "mixing") the two in the same system defeats the purpose of spending the extra money for the silicone.

On a related note, I was thinking before the "It turns!" report that the bearing journals might have developed a touch of surface rust that was causing them to stick to the bearings. I think I'd want to inspect them all and maybe even give each journal a quick polish with crocus cloth. Then brew up a mix of 15W50 or 20W50 motor oil mixed about 50:50 with STP, "Motor Honey," or one of the really thick viscosity index improvers, and coat the journals and bearings with that before reassembling.

Maybe not. That may be why the factory switched to motor oil. I wish someone would figure out if that new Pennzoil Synchromesh lube would work in the AX-15 and AX-5 trannies. I called Pennzoil when it first came out, and their engineer told me that lube was formulated for the NVG 3500/3550 and 4500 series transmissions. He didn't know what would happen if you used it in an AX-15 and he didn't care to speculate (at least, not to a customer -- wise man). I rather suspect it would work just fine, but I don't have a spare AX-15 to throw under the bus as a test specimen just in case it doesn't work just fine. Has anyone tried the stuff?

Crown used to offer them. Tried them? Call 860-274-8834. Click '3' for Parts, and try to talk to Todd, Fran, or Tony (in that order of preference). That's Bradshaw Jeep, my dealer. If Todd can't get it for you, it probably doesn't exist.

Front and rear axle? ==> SAE 80W90 or 75W90 GL5 gear oil (Newer spec is 75W140, that was not the spec in 1986 but better if you use it hard or tow) Manual Transmission? ==> 80W90 GL3 gear oil (Note: The GL3 is important if you have the AX-5 tranny, because grade GL5 has too much sulper and it eats the synchronizer rings) Transfer case? ==> ATF

Don't get fixated on the tank size and overlook the compressor. The compressor is what ultimately determines whether or not you can run your tools. A single cylinder compressor is NOT going to keep up with things like die grinders and sand blasters that basically run continuously. A larger tank will allow you longer "bursts" -- but a wimpy compressor takes even longer to refill a large tank than it does a small tank, which means you have more down time between slightly longer segments of actual work. Just like in car racing there's no substitute for horsepower, in compressors there's no substitute for CFM. Also, do not be fooled by horsepower "ratings." As I posted above, back when I bought my compressor they hadn't yet gotten into "rated" horsepower or "developed" horsepower -- they just listed horsepower. My 3-hp 2-cylinder compressor was THE largest available that would run on 115-volts. Period. Today you see "5-hp" and "6-hp" compressors for 115 volts, but if you read the fine print, they say something like "5 hp rated, 2 hp developed" or some nonsense like that. All it means is, 'We're not lying to you we're just not telling you the truth." Buy the compressor you need to do the work you'll be doing, and make it fit somewhere. If you don't, you'll forever be kicking yourself in the wazooskus. The only statistic that really counts is the SCFM the compressor puts out. If that's not higher than the requirement of the most air-hungry tool you plan to use, at the pressure the tool needs -- don't even bother.

Lots of people. Did you buy it at Auto Zone or Advance Auto? The prevailing wisdom is that aftermarket cluch masters ypically last about 6 months. This is one of those things where you should spend the dollars for a genuine Jeep part, or don't even bother doing the repair. I have no idea why an aftermarket won't last -- except that they are probably rebuilts rather than new, and honing them out probably leaves the bore too large to get a good seal on the wiper.

Gotcha. 10-4

You're buying a kit, with both the pressure plate and disc? The key part you have to match up is the tranny input shaft diameter and spline count, because that's what the disc rides on. I think they should be the same for the BA 10/5 and the AX-15, but I'm not certain. All of which says -- buy the kit based on the tranny, not the vehicle year. Is that bell housing set up for an external slave? If so, it's for a '94 or newer, and you scored big time. Much better setup than that goofy internal slave/release bearing thingie.

From I've been told, the factory clutches were made by Luks (Luchs?). The original on my '88 XJ lasted 204,000 miles and still had miles left when it was replaced in a pre-emptive strike when the slave cylinder went bad.

It's hard enough to follow some of the threads around here without going off on tangents that don't apply to the vehicle in question. Once the OP identified that he had an '88 4.0L, bringing up the 2.5L was just dragging the thread off-topic. I just try to keep things on topic. I guess it's a failing of advancing years. We olde phartes have to keep things simple so our diminished mental faculties can keep up.

They sold you the wrong sensor. Don't ty to use it -- return it.

If it was a 2.5 he would have had to. True, but ...