Eagle

Do you have a timing light?

Are you sure you got it at TDC on the compression stroke, not on the exhaust stroke?

Since you are the guy who runs his fuel gauge by direct wiring, maybe you know or can tell us if reversing the leads will make the gauge read the other way.

No. First: The 2.8L is externally balanced. That means there's a lump of weight on the flywheel or flexplate to help in balancing the rotating mass. The 3.4L is internally balanced -- it doesn't have that lump of weight on the flywheel/flexplate. So you'll need to take your flywheel or flexplate to a shop, have it neutral balanced, and use that on the 3.4L. Your engine is carbureted. The 3.4s are fuel injected. You will either need to adapt your vehicle to run with the FI system, or swap your intake manifold and carburetor onto the 3.4L. There's probably more, but that's what comes immediately to mind.

Factory rear window slider must be worth something. Even if you don't need it, it would be great if you could afford to pull it and set it aside.

"RR" means "Rear." I suspect that's a build code for a Cherokee with rear headrests. Remember, they recycle codes. A code that was used for an AMC XJ or MJ may well be is use today for some other Chrysler vehicle, and mean something different from what it meant for Jeep.

Turn off "autorotate"

Use anti-seize on the new ones.

I considered that awhile back, and I think I concluded that it wouldn't work. I was considering tracing the wires for the fuel gauge at the connector that plugs into the cluster, and seeing if it's possible to remove those wires and swap theeir positions in the connector body.

That's very sad news. Thanks for letting us know, Pete. Condolences to his family.

Be sure the radiator you get has a place to install the temp switch for the auxiliary fan. If you have an aux fan, the switch is mounted about halfway down in the driver's side radiator tank. Most of the radiators with a neck don't have that bung, because the HO system controls the aux fan through the PCM.

Just the filter. He is guessing that you installed a Fram filter, and they are known for screwing the oil pressure. Just throw on a good Wix or Purolator filter, add a quart to make up for what was in the filter, and check your oil pressure again. Most 4.0L engines run at 50 to 55 psi at around 65 MPH -- when brand new. If you're anywhere in the 45 to 50 psi range, you're good. But the pressure should not be below 13 psi at warm idle. (I don't like to see lower than 20, but the book says 13.)

Below 20 psi at idle, or at road speed? Factory spec for il pressure is only at normal operating temperature (meaning both the engine and the oil). The spec is 13 psi minimum at 600 RPM, and 37-75 psi at 1600 RPM. It doesn't sound like you have anything to worry about.

All those symptoms indicate that the turn signal sockets don't have a good ground, and are trying to ground by backfeeding through parking light circuit.

Neither gauge works, or neither gauge works in that cluster? Have you downloaded the electrical manual yet? If not, you need to find it and download it. That's where I copied the quick test procedure from. Did you run that test? What were the results?

Idiots!

I did the ZJ box swap in the 2001 XJ. I wasn't unhappy with it, but I also didn't get an "OH, WOW!" feeling from it, either. The old box had a lot of slop over center, and it was bad enough that it couldn't be adjusted out. The ZJ box eliminated the slop over center. Other than that, to be honest, I didn't think it drove any different than my two 2000 XJs. The difference in ratio, in practical terms, is 3-1/2 turns lock-to-lock for the XJ/MJ 14:1 box and 3 turns lock-to-lock for the ZJ 12.7:1 box. That means with the stock box, from straight ahead, you have to turn the steering wheel 1-3/4 turns to hit the steering stop. With the ZJ box, it's 1-1/2 turns. That's just not much of a difference. If I were buying a new box from Borgeson, I would ask if they can do one in a 10:1 ratio. I would especially ask about that if I had a long wheebase MJ.

If you read the instructions for that test, they tell you it won't shift into second. Did you test the fuse? Is the TCU getting power? You have an '89 -- that has the Power/Comfort switch on the dashboard, right? Have you tried flipping that switch?

Anything CAN be done. The question is whether ir SHOULD be done. You can probably find a way to hang a Cherokee tank under the back of an MJ, beneath where the spare tire is supposed to be. Of course, you lose access to the spare tire, which means you have to carry it in the bed ... which means you'll need to figure out a way to lash it securely in place. More importantly, the tank won't fit neatly up inside the frame rails (or X) -- it will have to hang below the frame. It will be at the very rear of the chassis, so it will be exposed to "tail strikes" (aviation term) when transitioning to steep grades, plus it'll be RIGHT THERE, waiting to get smacked if you get rear-ended. If you want to know why that's not a good thing, Google "Pinto gas tank issues." Here's a start: https://users.wfu.edu/palmitar/Law&Valuation/Papers/1999/Leggett-pinto.html https://philosophia.uncg.edu/phi361-matteson/module-1-why-does-business-need-ethics/case-the-ford-pinto/ https://www.history.com/this-day-in-history/fatal-ford-pinto-crash-in-indiana https://florinpopa.files.wordpress.com/2011/03/ford-pinto.pdf

What radiator neck? Your signature says your truck is an '89, and your opening post says you replaced the coolant bottle, so you must still have the coolant pressure bottle on the firewall. The radiator for the closed system doesn't have a filler neck. Did you "burp" the system after filling it? The closed system is very hard to fill, and almost impossible to fill in one try when cold. What I have found works is to fill it unti the level in the pressure bottle is half full, start it up with the cap on the pressure bottle loose, and let it warm up until the coolant starts to bubble out of the bottle. BE CAREFUL -- it's hot enough to scald you. As soon as it starts to bubble, shut off the engine. Remove the cap from the bottle. Wait while it cools down. In a couple of minutes it will start sucking coolant back out of the bottle -- when that starts to happen, add coolant to replace what's being sucked out, keeping the level in the bottle at least to the halfway point. When it stops sucking, start it up and repeat. You may have to do this three or more cycles to "burp" all the air out of the system.

Cherokee tank won't fit under an MJ.

Nope. Guages attach to the printed circuit board with two or three nuts. Temp gauge I think has three.

The best/easiest/most cost effective swap by far is the GM 3.4L V6. But it has to be from a rear-wheel drive vehicle -- Camaro or Firebird.

First question: What cluster did your MJ start with? The idiot light cluster, or the cluster with gauges but a large gas gauge instead of a tachometer? (Sometimes referred to as a "3/4" cluster.) If you started with a 3/4 cluster, then you already have the correct sensors to work with gauges. The temperature sensor is a variable resistor. The ratings are 1600 ohms at 100 degrees, 309 ohms at 180 degrees, and 113 ohms at 240 degrees. So a quick test would be to remove the pigtail from the sender. With the pigtail not contacting anything, that should cause the gauge to go to cold with the ignition on (engine NOT running). Then touch the pigtail to a good ground. The gauge should swing to the HOT side. If the original cluster had a temperature gauge, have you tried swapping your original gauge into the "new" cluster?