Eagle

I thought the manuals were 21-spline and the automatics were 23-spline. But I don't have an '89 so I've never paid much attention.

You have it apart -- throw in a set of bearings.

If I remember correctly, the procedure for bleeding the rear brakes on the MJ calls for performing a complete normal bleed first, THEN opening a front bleeder to trip the shuttle valve and allow bleeding the bypass circuit. Did you do a regular bleed on all four wheels first?

Yeah -- and their "stock height" springs lift the rear 3 to 4 inches.

There's your answer. Nobody knows how to get power out of a Jeep engine like Banks. (Banks also makes the only exhaust I have ever heard that makes a 4.0L I-6 sound sexy. Usually they just sound like an old Maine lobster boat, and the aftermarket mufflers just make the lobster boat sound louder.) Oh -- and you shouldn't compare a 90 to a 2001 -- they are the same basic block, but the intake and exhaust manifolds are totally different, the injection is different, the ignition is different, and the cam timing is different. The late model XJ 4.0L has a very different torque and horsepower curve than the Renix 4.0L.

The OEM closed system coolant reservoirs are not "expansion" tanks, and there is no pressure bypass. See my explanation a few posts above. They are designed to be filled no more than halfway when cold, so when the coolant gets hot and expands, it has an air cushion above it to compress. That's what accommodates the expansion. In an open system, the expanded coolant gets pushed out to the recovery bottle when hot, and it then gets sucked back into the radiator as it cools down. Too often, people don't understand how this works, they overfill the reservoir, and that's what causes them to crack. Liquid doesn't compress -- air does.

What "data" would you expect to be out there? The unibody (which the cab portion of the MJ is) was designed by a team of automotive engineers. AMC was in the business of building vehicles for a profit -- they wouldn't just throw extra pieces in there for no reason. The only "data" I need is that they didn't think the XJs needed the brace, and they did think the MJ needed it. That's all I need to know.

I would start by filling the overflow bottle to just above the MIN mark -- when cold. Check it when it reaches operating temperature. If it's at the FULL or MAX mark, you're done. If it's not anywhere near the MAX mark, add a bit more after it cools down.

What he said.

He has spark -- but he hasn't conformed that the spark is occurring when the #1 cylinder is at or near top-dead-center on the compression stroke. He could have the distributor installed 180 degrees out of time.

Specifically, an 87-93 2.5L 4-cyl recover bottle -- and using it requires getting rid of the factory air filter box. Not everyone wants to do that.

If you run it as a closed system, you can only fill it halfway. And then run a higher-pressure than standard radiator cap. Coolant expands when it gets hot. Something has to accommodate that expansion, because fluids con't compress. In an open system, the radiator cap allows coolant to escape to the recovery tank when it expands, and then allows the system to pull the coolant back ("recover") as it cools down. With a closed system, there is no spring-loaded radiator cap, and no recovery bottle for the expanded coolant to flow into. That's why the coolant bottle in the early 4.0 liter systems is only filled halfway when cold -- air can compress under pressure, so that air space allows for the coolant to expand by compressing the air in the plastic ooolant bottle. That's why it is so important to never over-fill that bottle.

No, you don't have to buy a new radiator. The Mac's tank is for the 87 thru 90 system, and it replaces the plastic surge tank. BUT -- The Mac's tank comes with a conventional radiator cap and a barb fitting for an overflow tube. Installing the Mac's tank IS a conversion to an open system.

Cut one out of a Cherokee.

You're allowing a shop to install that tank? The Mac's tank comes with a standard radiator pressure cap. That means it converts your system from a closed system to an open system. That barb fitting in the coolant neck is for a hose to connect to an overflow catch tank/bottle -- which your MJ doesn't have. You are going to have to decide where you want to install the catch bottle and find one that will fit.

What's your idea of "hot"? I have owned and driven regularly seven Jeeps with the 4.0L engine -- four Cherokees and three Comanches. They all run with the temperature needle pointing straight up, right in the middle of the dial. I think that's 220 degrees. If yours is overheating, it could be the radiator is clogged, or it could be that the viscous fan clutch is failing -- or a combination of both. If the temperature rises when idling in traffic and goes back down as soon as you start moving -- you need a fan clutch.

I like the Mac aluminum reservoir. I actually used Summit Racing surge tanks (also aluminum), but I bought those before the Mac reservoir hit the market. The Mac is more expensive, but it's a direct fit and doesn't require any adapters.

After that length of time, all rubber hoses and tubes should be replaced, gasoline should be emptied and discarded, and all electrical connections should be cleaned and checked.

There is no temp gauge sender bolt. Are you referring to the actual coolant temperature sensor? https://shop.advanceautoparts.com/p/crown-auto-jeep-replacmnt-coolant-temperature-sensor-53005056/11740438-P?searchTerm=Coolant+Temperature+Sensor I've also never had to remove that to get air out of the system. Any air should purge itself -- just keep adding coolant until the level doesn't do down any more.

Oh, yes.

Do you live in a place that requires emission or safety testing?

Springs, shocks, wheels ... plus a heavier-duty rear axle and bigger rear brakes.

I have an '84 or '85 XJ 2.8L hulk with a 228 or 229 transfer case out behind the garage. I'll probably pull the t-case before I scrap the body, but I have no idea what I'll do with it.

Are you saying you have one, or know of one? A BASE model 4-cylinder, manual transmission, with the 228 or 229 transfer case from the factory?

It's a base model. My guess is that it's got an NP207 transfer case. It'll give you 4WD, but it's not a particularly favorable transfer case. As I posted above, the internal oiling is inferior to the 231, and the low range isn't as low as the 231. However, it's attached to a transmission that won't fit your engine, so you would need to modify your transmission to make it work. Extremely unlikely that a 4-cylinder base model would have the 228/229 transfer case. That's a big, heavy, awkward lump of a transfer case. If that vehicle were in your town, I'd say get it, grab the axles, and part out the rest. If you're in Georgia and it's in Tennessee -- I don't think it's worth the time, effort, and gas money to drive up there and haul it back.