Eagle

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.

No ... and no ... and no. You don't "crack" any lines anywhere. http://comancheclub.com/topic/40428-brake-bleeding/ To add to those instructions: If the brake warning light does NOT come on, you're not getting it right. The second line to the rear is a fail-safe line that sees brake fluid/pressure ONLY if the front circuit fails, and the shuttle valve that triggers the warning like slides off center to open the bypass port. No light ==> no bypass. Opening the front bleeder simulates a front brake failure.

There is no adjustment for discs. Did you follow the factory procedure for bleeding the rear circuit?

BAD idea. You're replacing one 20+ year old part with another 20+ year old part that's going to be just as bad. There's a replacement socket, with pigtails, that's in the HELP! aisle at most of the auto parts chains that's a perfect fit. It's not listed for Jeeps, it's listed for some Ford vehicle or other, but it works perfectly. Just take in your old socket and match up the tabs on the bayonet lock mount.

Tried it, didn't make a difference. Both the bulb and socket contacts are clean, what else could it be? Tried it, didn't make a difference. Both the bulb and socket contacts are clean, what else could it be? Bum socket. I've replaced a whole bunch of front turn signal sockets on XJs and MJs over the years, and I've seen a bunch more as used vehicles or in junk yards where some previous owner beat me to it.

Go to Lowe's or Home Depot or a large Sears HARDWARE store and buy the shortest 1/2"x20 bolt you can find, and a 1/2" I.D. O-ring. Cut the bolt to a length that will barely allow the head of the bolt to seat on the valve body when the tip of the bolt contacts the seat inside the bore, then cut or grind it just a tad more -- not more than 1/16 of an inch. Put the O-ring on the bolt. Put a dab of silicone RTV on the end of the bolt and allow it to set up, then screw it in enough to slightly compress the O-ring. Done. I think the threaded portion of the bolt will need to be about 3/8" to 7/16" long, but it's been a few years since I last did one so I don't remember for sure. Might be as short as 5/16" but I don't think so.

Nice photo of the garage. Is there supposed to be an airplane in there somewhere?

If the rear circuit wasn't bled properly and the rear height sensing valve is till in place, it is likely that the rear circuit has air in it and that would be enough to trip the warning light.

All good info on leaks, but ... ... the problem here seems to be electrical on top of a suspected fuel leak. The leaks probably won't prevent the engine from starting ... but they may set it on fire. The no-start until you jiggle the injectors sounds like a wiring harness issue. Trying to trouble shoot TWO problems -- which may or may not be interrelated -- is never fun.

If you can smell fuel, you should be thanking the deity of your choice that it WON'T start. True story: One of my friends from NAXJA a number of years back smelled fuel and deduced that the injectors in his heavily and extensively customized MJ were leaking. So he drove to the dealership and went into the parts department to buy an O-ring set. He came out of the parts department a few minutes later to find his heavily and extensively modified MJ fully engulfed in flames. The truck was a total loss. If you smell gas, DON'T drive it until you identify the problem and fix it.

Give us a hint -- what was the problem?

It should look exactly like your old one did. As noted above, you probably cross-threaded it.

I specified the rear because my experience is that the front windows get used a lot more, so they are usually not worth bothering with.

A window handle from the rear door of a 4-door Cherokee.

It almost certainly is the alternator. I went through this with my '88 Cherokee and again with my '88 Comanche. Remove the alternator and take it to Autozone or Advance Auto to have it bench tested.

I've found that this is usually due to a dirty idle air sensor (IAS). However -- if this is a Renix 4.0L, there's another possibility: The throttle cable from the gas peddle doesn't run directly to the throttle body. The cable runs to a bellcrank mounted down low on the driver's side frame rail, and from there it's a rigid connector. I have twice had that bellcrank pivot get either rusted up or gunked up, so that the return spring wasn't strong enough to pull the engine down to idle. Soaking the pivot with PB Blaster cured it. Other times, when the high idle was due to the IAS (which is more common), running a few cans of fuel system cleaner through the tank cleared it up.