Eagle

i started questioning it when it took that long and my dad was curious of why it did as well. i've driven cars older than that truck and they started up like a brand new car. so i thought it was odd. It is a peculiarity of the Renix system. I don't understand the specifics, but the Renix system doesn't "learn" any settings from driving. Every start is a "clean boot" for the system, and it needs a number of engine revolutions to check and be sure that everything is synchronized before it'll actually fire up. There is no way you will EVER get a Renix system to fire the instant you turn the key. Just accept it -- it ain't gonna happen.

You "fix" the light by unplugging the timer box. But as Pete wrote, the timer is not a tester. The only way to test your oxygen sensor is to hook the truck up to a sniffer and see if it's running rich. The O2 sensor is supposed to be replaced every 75,000 miles. The conservative approach when buying a used truck is to assume it's due and replace it. If it improves your fuel economy by a couple of MPG, at today's gas prices the new one will pay for itself quickly.

It's a '91 -- does it have a front axle disconnect? The last year for the disconnect in the XJ was 1990, and I always thought the Comanche was the same. So if it has a disconnect, there is a possibility that the front axle isn't original to the truck. Nonetheless, you could put all four wheels up on jackstands so no tires are touching the ground. Start engine, shift transfer case into 4WD and the front disconnect will engage. Turn off engine and the disconnect should remain connected. There's no spring in there -- it'll stay connected until the vacuum sitch sees you're back in 2WD and pulls the shift fork the other way.

No, you cannot tell by looking. The accelerator pedal cable leads to a "bellcrank" linkage that's down low on the left (driver's) side of the engine. There's a vertical rod that comes up from that bellcrank to the upper end that operates the arm on the throttle body. That lower bellcrank can get rusted and nasty, which results in the throttle sometimes not returning to the idle position. It has happened to me twice. You can't see it -- it doesn't look like there's anything wrong. But after spraying liberally with PB Blaster and working the linkage some, my idle went back to normal. That's not the only cause of a high idle, of course. The other ... and more likely ... cause is the idle air controller (IAC), which has already been mentioned to you.

I can't think of a good reason for a previous owner to have a 4WD truck with no front drive shaft -- unless he swapped one of the axles and wanted to be certain he wouldn't accidently put it into 4WD and break something. If the front axle is original and un-tampered with, there should be a tag with the gear ratio. The rear axle probably will not have a ratio tag, so you'll need to resort to other methods to determine that ratio. Let us know.

It would be more useful to add more weight, until you get the frame to sit on the bump stops. Then check to be sure there is still SOME clearance (don't need much, but enough to be sure the yoke isn't slammed into the tailshaft housing).

The fact there was no front driveshaft is what we call a "clue." Have you verified that the front and rear axles have the same gear ratio? If not (which is what I suspect will be the case), they will be fighting each other in 4WD.

Errr ... no. I confess. I'm Photoshop challenged.

The Schraeder valve can be used to bleed off fuel pressure. Keep in mind, I wrote "fuel" pressure. If the line has been pressurized, you're not letting out air, you're squirting gasoline. You can put an absorbant rag there to catch it, or try to direct it into a container. Yes, it's probably more controllable than disconnecting a pressurized hose at the fuel filter underneath. The post with which I took issue earlier today referred to using the Scraeder valve to bleed off 'air" -- after having been trying to start a truck that isn't cooperating. That's a good way to spray gasoline around, and gasoline squirting unexpectedly has a way of seeking out anything hot or glowing and starting fires. I wasn't suggesting that the Scraeder valve should not be used as intended. I just wanted to cauthion that it should be used as intended, and not carelessly by people who don't understand what's supposed to come out of it.

Before you take it apart, check it more carefully. The two hoses attach to metal tubes that penetrate the mounting flange. Many of us have found that the weld (or braze) where the tubes go through the flange cracks, and that's where the leak is. I found out the hard way -- I replaced my tank with a new one, used a new locking ring and O-ring, went to the gas station ... and dropped several dollars worth of gasloline onto the pavement before I realized there was anything wrong.

That method has failed me. I've rounded off a couple of Torx bits that way, and snapped one. Sears only provides a lifetime warranty on their Craftsman brand tools. I bought my bit set at Sears, but it's a Lisle brand. "So sorry, Charlie."

By all means, one must appease the gods of fire ...

No, you may NOT be good. You NEED some gap because the driveshaft is at an angle. When the suspension compresses, the angle flattens out and the distance between the tailshaft and the rear axle is reduced. You need enough clearance for the slip yoke to ... slip ... into the tailshaft to take up that change in distance. If you don't have enough gap to allow the axle to compress to the bump stops, you risk breaking things.

If you can get to the U.S.S. Constitution, it's worthwhile. But it ain't near your hotel. While in Boston, at least once you should dine at "Legal Seafood," the Boston area's best seafood restaurant. There are a few around, and the clam chowder is to die for. Who is "we"? If you'll have kids along, or if "we" is you and your significant other and you like a bit of fun, look into the Boston Duck Tour. They run out of the lobby of the Prudential Center, which shouldn't be far from your hotel. It's a fairly conventional bus tour around the historic center of Boston -- except that the buses are old WW2 amphibious landing craft, and at one point in the tour they drive into the Charles River and show you a view that none of the other tours can match. The historic center of the city is Boston Common. It's a big park, basically, but the historic New England cities and towns all grew up around a village "green," so it's more than just a park. And the actual Cheers is right near the Common. Fanueil Hall marketplace is the old Customs House complex, converted into trendy shops and nosh joints. It doesn't do much for me but my wife enjoyed it when we visited Boston last year. And if you're into baseball, don't forget Fenwick Park, one of the last of the old baseball stadiums, steeped in baseball history. [Oops - never mind -- just re-read your post] On a Friday or Saturday evening, duck across the Charles River to Cambridge and hang out around Harvard Square. In the summer it's a great street scene, with musicians on many of the corners (and from various corners of the world). If you look closely, while walking around Harvard Square you can see the windows of the infamous "Dewey Cheat'em & Howe" law firm made famous by the Car Talk guys (the Tappet Brothers). Click & Clack hail from Cambridge and that's where their show is produced.

I've never used the petcock. It's in an awkward to access place and I'm paranoid it'll snap off. Pull the lower hose.

Parts for a 4.0L with internal slave cost me (IIRC) about $250 a couple of years ago. That included the clutch (disc and pressure plate), new factory slave cylinder and new factory master cylinder. The price you're being quoted sounds rather on the high side, but remember that dropping the tranns and tranfer case out of a 4x4 is a lot more work than doing a clutch in a simple 2WD automobile.

How are the outer axle bearings? I would try repacking the bearings, replacing the gear oil with 75W140 synthetic, and adding some moly additive (Google "Mr. Moly") and just drive it. 31s shouldn't kill it.

With an automatic, it could well have been 3.73s

Nice.

Bad choice. There is a LOT of collective experience in the XJ/MJ community that for clutch hydraulic parts the aftermarket stuff simply doesn't hold up. Typically, you'll get maybe six months. This is one place where the only safe choice is genuine factory parts.

The Renix system is already a high-energy system. Why waste money on aftermarket stuff that's at best a marginal improvement? If you want high-performance wires, they are available through the Mopar Performance Catalog. BLHTAZ can probably hook you up, and the Mopar stuff is far less expensive than the "name" stuff. (And just as good.)

man thats ancient..... still better then mechanical drawing though.. thats prehistoric these days.. I still prefer to think of it as "Descriptive Geometry." And if you can't do it manually, you probably can't REALLY do it in AutoCAD. Between my consulting architect practice and my part-time gig as a building inspector, you'd be surprised (or maybe you wouldn't) at some of the stuff I see on plans ... stuff that absolutely, positively could not be built the way it's drawn no matter how long somebody tried to fight with it. And I've watched some of the drafters produce that dreck -- try to point out politely that it can't be done that way, and they get huffy and tell you they're not being paid to think, they're only being paid to put lines in the screen. I kid you not.

Oh, God! I feel SOOOOOO old now ... I remember taking adult ed classes for AutoCAD Release 10 -- for MS-DOS. With a tablet and puck. Thanks, Pete. You'll pay for this.

So, for a 265/75/15 tire the calculation for the diameter is: 10.43 X 0.75 = 7.82 (side wall height) 15 + (2 X 7.82) = 30.64" diameter, right? That's pretty close to the 30.5 that I measured for my nominal 31" tire. Or am I screwing up my calculations somewhere? Nope, you're not screwing it up. That's how you figure it. Keep in mind, that's the unloaded profile. The best measurement is the "static radius" taken from the manufacturer's specs, or the revolutions-per-mile. Different tires have different sidewall stiffness, which affects how much a given weight will defect the sidewall. Several years ago, Cooper Tire offered the original Discoverer radial in a P-rated, passenger car version and in an LT light truck version. Same tread, same sizes. The static radius and revolutions per mile were different for the two tires in, for example, a 235/75R15. But, for a spare, getting something that's within a quarter inch of the tire diameter will probably be as close as you're going to get.

265 / 25.4 = 10.43 That's not much of a difference. Try an 85-series tire.