Eagle

A 2.5-liter with a 4-speed manual (AX-4, not AW4) will have 3.55 axle gears. 4.10s were used with the 2.5L and the 5-speed.

IMHO for a Renix engine NGK plugs are best -- the standard ones, not platinum. Close second are the Champion truck plugs.

That explains why the transmission went walkabout ...

Sheesh! After all that ... it's only the electical manual. You won't get much help rebuilding the engine out of that ...

Link seems to be working for me, although it's taking forever to download. Must be a huge file.

I vote for the '92.

The oxygen sensor usually addresses hydrocarbons. NOX is usually caused by a lean condition, IIRC. Carbon Monoxide -- I don't remember what causes that. Do you have methanol-doped gasoline where you are? I'd suggest dumping a can or two of fuel system cleaner into your tank and driving it down to almost empty, then fill up, go to your favorite parts house, and on the shelves where they have all the chemicals buy yourself a can of one of those "Guaranteed to pass emissions" snake oil products.

Even the early, smaller 8.25s are superior to the Dana 35, despite having the same diameter shafts. A major weakness of the Dana 35 is the axle tubes bending where they enter the diff housing. The Chrysler 8.25 has larger diameter (and heavier wall???) tubes, which pretty much eliminates this problem. Of course, if the OP's truck is truly a Metric Ton model, it would not have had a Dana 35 ... it should have a Dana 44. For most purposes, though, either 8.25 will be quite serviceable. Both my '88 XJ and '88 MJ have Dana 35s and have been wheeled all over New England (and the XJ has also been to New Mexico and points west) with no rear axle problems.

You were misinformed. They all (all the 4.0Ls, that is) got the Peugeot until mid-1989, after that they all got the AX-15.

This would be the '87 Comanche in your signature? The 5-speed transmission in 1987 was the Peugeot, so you probably have the original transmission. Unless you really like to beat on your transmissions, that's not as bad as many people make it out to be. My '88 XJ was bought new by me. It has the Peugeot 5-speed, and it's currently at around 287,000 miles, and should be good for a lot more. Just remember that it's not a BMW, it's not a drag race transmission, and if you try to slam shift it you WILL break it. Don't know what to say about the rear axle. If the truck is a Metric Ton truck, verified by VIN codes, then it should have a Dana 44. He could have destroyed the D44 and just tossed in what he could get easily and cheaply. MJ Dana 44s don't grow on trees.

http://comancheclub.com/topic/35337-posting-pics/

I think the reason they don't list for the MJ is because of the height sensing valve for the brakes. If the truck does not squat for the added weight then you won't get more brake pressure to help stop the extra weight. I have never found any overload or air shocks listed for the MJ. That's an excellent observation, and probably right on. The dimensions are basically spot-on for a stock MJ, so there had to be a reason not to list them, and for a manufacturer with deep pockets like Tenneco, selling something that would detrimentally affect the braking would be a HUGE liability.

It could be the track bar ... but it also very well might not be. It could be one or more tie rod ends ... but it also very well might not be. It could be one or more bad ball joints ... but it also very well might not be. It could be a worn steering box ... but it also very well might not be. There are a LOT of things it COULD be, but until you have a better idea what it IS ... don't start buying parts. Do your homework. Get a helper, and do basic diagnosis. Park the truck on a level surface, front wheels straight ahead, chock the rear wheels, and put your helper in the driver's seat. YOU put on a nitrile glove and crawl under the front of the truck. Have your friend turn the steering wheel back and forth about 1/4 turn left and right of center. Maybe a bit more, but not much. What you want is to turn the steering enough to load the various parts, but NOT actually move the tires' contact patch on the ground. Start with the track bar. You can feel movement before you can see it. Put your hand around the connection where the track bar bolts to the axle. As your helper turns the wheel back and forth, do you feel movement between the track bar and the axle? Then move to the upper end of the track bar. This end looks like a tie rod end, and it works the same way. same drill -- while your helper turns the wheel back and forth, grab the TRE and see if you can feel any movement between the track bar and the frame bracket. There should be none. Move to the front wheels. There's a tie rod end just inside each front wheel. Check em for flex while your helper turns the wheel. Then check the opposite ends. One has another TRE at the pitman arm, and the tie rod itself has another TRE when it attaches to the drag link. Chances are, one or more of those points will reveal slop. If so, that's where you start the replacements. Don't just guess wildly and throw parts at it. Murphy's Law guarantees that if you go that route, the LAST part you replace will be the one you should have replaced first.

Okay, then engine RPMs at 65 MPH should be: 3.55 ==> 2892 3.73 ==> 3047 4.10 ==> 3349 4.56 ==> 3725 4.88 ==> 3986 Don't discount the possibility of 4.56 gears. A number of years ago I picked up an '84 or '85 XJ Wagoneer ... with a 4-cylinder automatic. It had the same transmission and transfer case you do. I bought it only to keep it from being junked, and a year or two after I bought it I gave it to a guy in NAXJA NAC from northern Massachusetts. It was supposed to be for his daughter, but then his XJ crapped out and he used it as a daily driver for a year or more. But I digress. The point was, I picked him up somewhere in MA and brought him down to my home to pick it up, and he drove it home. We talked either late that night or the next day, and he reported that it ran fine except that the tach was showing alarmingly high RPMs on the highway. He opened up one of the diffs and discovered that it did, in fact, have 4.56 gears ... and it apparently had come from the factory that way. Things like axle ratio were a lot less standardized back in the days of the early AMC XJs and MJs. The factory wasn't shy about offering optional axle ratios.

Except that the factory rims were all 7-inch (except the ones that were 6-inch).

I'm 100 percent certain of my figures (to within about 1 to 2 percent deviation). Years ago I went to tire manufacturers' spec sheets and looked up their actual revolutions-per-mile data. That's the most accurate way to correlate engine speed to road speed, and those data were what I used to generate the spreadsheet I built up to show engine RPMs are various road speeds for all the tire sizes typically used on XJs and MJs, and for all axle ratios from 3.07 through 4.88. But the OP didn't say 75 MPH, he said 3700 RPM at 65 MPH. He also didn't say what tire size he has, and I don't remember what sizes were stock in 1986. I took a guess at 215/75-15 and used those numbers. I just realized, after re-reading the description of how his transfer case works, that he has the NP228 Selec-Trac case, not the NP207 Command-Trac case. So I don't think his truck is a base model. Therefore, unless/until he says otherwise, I think we can generalize on 225/75-15 for the tire size. I don't know if the 2.8L was ever sold with 3.55 gears. I have the remains of an '86 XJ with the V-6 and the 228 transfer case out back -- it has 3.73 gears, which I verified. That's why I assumed that the OP probably has 3.73 gears. But ... what if he has 3.55s? For 3.55 gears with 225/75-15 tires, 65 MPH is 2800 RPM. Now ... if he has a 4-cylinder tach in there, 1.5 x 2800 = 4200. Too high -- so that may not be the answer. And if he does have 3.73 gears it would get even worse. I would suggest that the OP beg, borrow or buy (but not steal) a hand-held tachometer, or get some time on a shop scanner, and run the engine against a calibrated tach to compare what the diagnostic tachometer reports compared to the one in his instrument cluster. Second gear ratio in that tranny is 1.55. If he's supposed to be turning 2800 RPM at 65 MPH, but the tranny is stuck in second, that would work out to 2800 x 1.55 = 4340. Nope -- that's not the problem, either. Could be that the torque converter ISN'T locking, and that it has a lot of slip.

Vacuum what? The second line to the rear is an emergency bypass line. If the shuttle valve in the front distribution block hasn't moved off center, the port to the second (bypass) rear circuit isn't open and you can't pressure bleed it, you can't vacuum bleed it, you just can't bleed it at all. Open a front bleeder all the way, put a tube from it into a can or bottle, then stomp on the brakes. There needs to be a pressure differential between the front and the rear for the shuttle valve to move.. If there's a lot of air in your rear circuit, you may not be generating enough pressure difference to move it.

What's the 8th character of the VIN? 7 = X (base) 8 = XL 9 = XLS F = Custom w/ Metric Ton G = X w/ Metric Ton H = XL w/ Metric Ton J = XLS w/ Metric Ton

Actually, that's dead on for an MJ at stock height. Monroe lists two standard shocks (not coil-over) for the rear of the MJ. 31094 Compressed Length = 13.375 Extended Length = 23.125 37029 Compressed Length = 14.375 Extended Length = 23.000 The Load-Leveler you listed has a total travel of 9.375". Assuming it rides at mid-travel with the bed unloaded, you have 4-3/16" travel up or down. I'd say you're good up to about a 2" lift. Any more, and you've used up almost all the extension, so you'll have no droop at all.

You should not have to slam down on the brakes, but the front bleeder has to be OPEN. There is nothing to experiment -- you are trying to simulate a FAILURE of the front brakes, so you want the front bleeder wide open, so it dumps the fluid.

. Per Pete M's info, top gear if no overdrive should still be 1:1 ratio, therefore earlier assumptions hold. . xjrev10 reported four shifts. Could the 4th shift be the torque converter locking in a 3-speed? That was my thought (torque converter lockup) as well. I don't think the t-case is in low range. The '86 would have an NP207, with a low range of 2.6:1. If the correct speed should be around 3,000 RPM, multiply that times 2.6 and you get 7,800 RPM. What model MJ is it? Could it be a swapped in instrument cluster out of a 4-cylinder? Lemme think again which way that goes. 4-banger has two pulses per revolution, 6-cylinder has three pulses per revolution. So say a 6-cylinder is turning 1000 rpm. That would be 3000 pules for the tach to read 1000. A 4-cylinder only has two pulses per revolution, so the same 1000 RPM would be 2000 pulses. Feed 3000 pulses to a 4-cylinder tach and it'll read 1500 RPM, not 1000 -- in other words, 50 percent faster than the engine is actually turning.

4th gear? I thought that was a 3-speed tranny. And my 1986 Comanche FSM confirms this. First gear is 2.74:1, second gear is 1.55:1, and third gear is 1:1. With the V-6, the most likely axle ratio was 3.73. If the stock tires were 215/75-15, with 3.73 gears the engine should be turning 3047 RPM at 65 MPH. If it has 4.10 gears, it should be turning 3349 RPM at 65 MPH.

I think most everyone knows (or should know) that PB Blaster and similar solvents are designed for breaking down iron oxide (rust) on corroded ferrous metallics and should never be used on electrical connections of any kind. Also dielectric grease is an non-conductive insulator, designed to prevent moisture entry to electrical connections. If used on a copper metal-to-metal electrical bond it increases resistance. Dielectric grease is used is to coat rubber gaskets and boots to prevent water entry to the electrical connection. ^^^ What he said. Do NOT use dielectric grease directly on the contacts. It IS an insulator, it is NOT a conductor.

You are looking at the front distribution block. That's also the proportioning valve in a Cherokee. It is NOT a proportioning valve in the Comanche. The proportioning valve is mounted to the frame, above the rear differential on the driver's side. It has an arm on a pivot, which is supposed to be (but often isn't, on old MJs) connected to a ball stud on the differential by a vertical rod.

How many leaves are in your spring packs now (not counting the overload leaf)? Five? Six? IMHO, if you're bottoming out a suspension using beefed-up MJ springs plus add-a-leaves, you are SEVERELY overloading the vehicle. Adding helper springs of any type is only going to cause you to overload the truck more, and the chassis simply isn't (wasn't) made to carry more than the rated load. Don't add more spring -- subtract load. Or buy a heavy-duty, full-size 1-ton truck or a mason's dump.