Eagle

A control arm wouldn't sound as metallic as a wrench on a metal fence. I'm in over my head on this one. Sorry.

Both the 3.1L and the 3.4L are excellent swaps. Both are a huge improvement over the 2.8L, and they are the same block so it's an easy replacement. Just be sure to get one from a rear wheel drive donor. And, unlike the Buick, they aren't so much more powerful that they'll destroy the rest of the drive train immediately after installation. The 2.8L has an externally balanced flywheel. The 3.1L and 3.4L are neutral balanced. You'll need to take your 2.8L flywheel to a shop and have it neutral balanced.

"Clank" is suggestive of metal-on-metal. I very much doubt that a hub/bearing unit could make a "clank" and still roll. I also don't think anything inside the differential would make a noise that would sound like a "clank" inside the cabin. Is it really a "clank"? How about a "clunk"? I get a lot of clunking in the "new" (to me) 2001 XJ, and I have traced it to the upper control arms being shot. Too cold to change them now, and not critical, so we just soldier on until warmer weather arrives. Have you checked your control arms?

The reason I have reservations about the 87s is that the dial faces in my '87 MJ Pioneers are the old style markings, with ticks for every one MPH, not like the '88 XJ Pioneer that only has ticks at the 2.5 and 5 MPH intervals. It has been my guess that the old-style face probably has the old style cluster behind it, but I've never bothered to crawl under the dash and look.

Won't work. The '95 tank is just an overflow catch tank. The early, closed system tank on the firewall is a pressure tank that is a part of the pressurized cooling system. The cap is a pressure cap. Quadratec sells (or used to sell) new tanks and caps. If that's too much for you, some other GM and Mopar cars have used similar systems over the years and I've seen reports of junkyard pressure bottles from other makes that work. I think even the Jeep Liberty uses a pressure tank. Check Quadratec, and visit your local u-pull junkyard. See posts #11 and 16 above

Actually, the early 89s had it, too. The elimination of the C101 connector was a running change midway through the 1989 production year.

No. To be safe, 1988 through 1990, not "pre" 90. The earlier XJs and MJs used a different speedo cable attachment. Unless you want to also change the speedo cable, you can't use the cluster from an 84-86 in a 1988 vehicle. Also, the 88 and up have a potentiometer that allows setting the tachometer for 6-cylinders or 4 cylinders, so it doesn't matter what engine was in the donor vehicle. The early tachometers don't have this adjustment. You'll notice that I have carefully avoided mention of 1987. That's because, even though I have both an 87 MJ and an 87 XJ, I have never pulled the cluster out of either one and I don't know if the 87 used the arly style speedo and tach, or the late style speedo and tach.

A 4.0L doesn't have a PCV, and the tube that opens into the air cleaner box isn't the suction line for the CCV system anyway, it's supposed to be the inlet for air to go INTO the valve cover. The suction tube is the small plastic line off the back end of the valve cover. What happens is that it gets clogged and there's no suction, so no way to evacuate the oily fumes from the crankcase. Plus as the engines get older and more worn, there's more blowby at the rings, so the crankcase becomes pressurized rather than being a partial vacuum. The oily fumes can't go where they're supposed to go, so the system works in reverse and pushes the fumes back out through the inlet tube into the air box. The water you see mixed in is condensation from cold weather operation.

The alleged C101 problems, IMHO, are vastly exaggerated. Back around 1990 the dealer from whom I bought my '88 Cherokee had gone out of business. I took the XJ to another dealer for some minor service, and the service manager mentioned a TSB on the C101 connector that he claimed would cure all sorts of problems. So I told him to go ahead. The TSB was to cut out the C101 connector and splice all the wires -- it cost me several hundred dollars, and after all that the result was that it didn't accomplish ANY of the improvements he had said it would. I mentioned that the next time I was there, and the lying [bleep] then claimed he never told me it would improve anything. Needless to say, I never went back to that stealership. Meanwhile, I have an '87 MJ and two '88 MJs that all still have the C101 intact, and there have been no problems with any of them that can be attributed to the C101.

No, the LWB also offered a small tank. The external dimensions are the same as the 23.5 gallon tank, it just has baffles inside to reduce the capacity. They did the same thing with the early Cherokees. I believe it had something to do with minimizing curb weight to maximize fuel efficiency on the government mileage tests. The SWB only had one size, as far as I know.

^^^ This. The early (Renix) XJ and MJs sometimes had a problem with a weak signal from the CPS to the ECU due to the fact that the CPS fed through the wiring harness to get to the ECU. The factory released a fix that bypassed the wiring harness, using a new connector that went directly through a new hole drilled in the firewall and straight into the ECU. For an 89 or a 90, the original CPU connector wires should go into the big wiring harness. If the CPU connector has two wires that run directly through the firewall, that vehicle has had the bypass performed.

I have to disagree. Mounting the anchors for the shoulder straps will be a real problem in an MJ cab, but the practicality of using a 4-point harness on the street is nowhere near as bad as you make it out to be. For several years, when I was campaigning a Javelin in Autocross, time trials and hillclimbs, I ran a Simpson 5-point harness in the car. I used all five when racing and skipped the anti-submarine belt when driving it on the street. It wasn't at all uncomfortable, and it wasn't at all inconvenient. Tightening the straps doesn't require help. The tabs fall within easy reach. Once adjusted, you know they are adjusted. There's no wondering if the retractor is going to fail when you need it to grab. But ... I had a roll bar to attach the shoulder belts to, so I had the correct angle. I don't know where you could anchor them in an MJ other than bolting through the rear wall of the cab just below the window.

If he can shift it manually, the transmission obviously works. The problem is either the fuse for the TCU, or the TCU itself.

Zinc chromate kills rust? I know it has been used as a primer for many, many years, but I have NEVER heard that it kills existing rust. Got a link to some documentation on that?

Can't be done with the stock Jeep wheels because there are no retainers to hold the moon caps in place.

If the thermostat was stuck open I doubt very much there would be normal heat coming out of the heat vents.

Is the school's truck 2WD or 4WD? If it's 4WD, you could replace the 3.08 axle with 3.55 and it'll drive a lot better. If it's 4WD, of course the rear axle has to be the same ratio as the front. As noted, Cherokee axles are the same except for the location of the spring perches. I'm pretty sure I have a 3.08 axle buried under the snow outside. Once the snow melts, if you haven't found anything I could send you the gears if your instructor has the skills to set up a differential.

ECU? I thought the fuel pump relay was triggered by the fuel pressure regulator. What year MJ are we talking about, anyway?

Welcome. If we don't have answers for you ... answers probably can't be found. Some of our answers may even be correct. We don't even charge extra for those.

The ratio for the manual steering is ridiculous -- something like 24:1 or 28:1 ... compared to 14:1 for the power steering. I haven't had manual steering in an XJ or MJ but I remember the factory manual steering from my Javelin days. The ratio on that was 20:1 and it was horrible. Not too heavy (I changed all mine to the 16:1 quick ratio manual boxes for autocrossing), but much too slow. With the XJ/MJ manual boxes being even slower -- I can't even imagine how horrible it would be to drive one. Don't even want to think about it.

I'm going to guess control arm. When bad they make a very noticeable clunk, and because they are a steel sleeve inside a rubber bushing they always have some play anyway ... so it's difficult to diagnose them visually.

Factory spec is zero camber -- dialing in camber is the worst thing you can possibly do for a street vehicle, unless you have lots of money and REALLY enjoy buying tires.

Get a TruTrac. It's a gear-actuated limited slip. More aggressive than the clutch-type Trac-Lok, but still street friendly for daily driving.

They can do the alignment, they just want to sell him parts. My brother used to be service manager for a BMW dealership. One of his biggest problems was doing battle with certain of the technicians. When a car would come in for service, instead of getting to work fixing whatever the complaint was, their priority was always to waste a bunch of time going over the car to see whatever they could find to "upsell" more parts and labor. I view it as an evil aspect of the auto service trade. Virtually all shops today pay technicians and service writers a percentage of whatever parts and services they can sell, so there's a big incentive to sell parts that aren't needed. The worst part is, when you decline the unneeded parts, there's a high probability the tech will get pee-oohed and do a crap job on the work that DOES need to be done.

They ALL leaked -- right from the factory. I bought my '88 XJ new, and the operable vents were an extra-cost option that I paid to get. They leaked right from the day of delivery. The factory had a cure -- they offered to replace the operable windows that I had paid extra for with the standard, non-operable windows. (Naturally, they weren't going to refund the cost of the option from my purchase price.) If you plan to use the vents, plan on their leaking. There is NO way to stop it. I sealed the ones on my XJ with silicone and I haven't opened them for more than 20 years. Fortunately, none of my MJs have operable vents.