AZJeff

Installing an XJ tank will destroy your ability to carry a spare tire in the OEM manner, and that means the spare goes in the bed (or you take a chance and skip the spare ) What I did was based on recommendations from fellow CC member "Dzimm" I installed a 22 gallon plastic gas tank from a 1998 Dodge Dakota pickup. The Dakota uses the more modern style of fuel pump commonly found on the XJ's as well, so there may be some adaptation needed for your wiring to connect to that pump/fuel sender unit to your older MJ wiring harness Dzimm can probably chime in on any special tricks for that wiring, as he was an invaluable source of info when I converted my MJ.

I don't like Rancho suspension parts in general, so I an going to suggest an alternative for the front: KYB They are modestly priced, and provide good balance between dampening and ride. Another good choice is Quadratec's house brand of shocks.

The windshield in an XJ (and MJ) is glued in with special urethane adhesive intended for automotive windshields. The adhesive is thick and strong, and the bead that attaches the glass to the cab is normally 1/2" to 3/4" wide and about 1/4"-3/8" thick. An auto glass shop will normally use a special utility knife with a handle about 16" long to cut the adhesive around the glass perimeter from the INSIDE of the cab. Once that is done, the glass can be pulled out. If you intend to try to salvage this glass, you will need to use the method described above. (The long knife handle gives you better leverage to cut the adhesive.) By the way, if you intend to ever install this salvaged glass, you will need to clean virtually ALL of the old adhesive from the glass once is removed so that new adhesive can be applied to the windshield when you install it into it's new home. One last thing--the trim around the windshield on a 2001XJ (that covers the gap between the glass edge and the body) will be a one piece rubber "ring" that slips over the edge of the glass prior to installation. The trim on an MJ as built at the factory would have been a series of metal pieces that attach to clips on the body to cover thet same gap. I prefer the later XJ style of trim, because it's easier to install, and eliminates any potential for rust to form between the metal trim pieces and the painted body. The good news is that the later rubber-ring trim from the XJ will work just fine on the MJ, as long as you remove the small plastic clips that were used to retain the metal trim when you install the rubber-ring.

An emissions test report would be helpful to make sure the OP is actually attacking the correct issue with new parts.

Let's start with some basics. I think your emissions failure is due to "excessive hydrocarbons", as that is the term used when evaluating exhaust emissions. Excessive hydrocarbons (aka "high HC") is in indication your Jeep is not burning the fuel correctly, meaning that there is too much fuel for a given amount of air entering the engine, or what fuel it IS getting is not burning fully due to poor compression, or poor ignition, or both. I assume you have some sort of formal report from a Delaware state approved emissions testing facility that would indicate what the results of their testing indicated. If you can attach a copy, or transcribe what is in the report, it would help us figure out what is going on. Just guessing and trying this or that is likely to be an exercise in frustration, so we need more details.

No, I do not, unfortunately.

Where did you source that evaporator? ( It's not a 97+ XJ type, BTW.)

YES, that is correct.

SoCalJeepComanche hooked me up with my semi-custom set of decals/stickers for my MJ. Mine is slightly unusual in that I have a 2000XJ's driveline in it, so my underhand "emissions" sticker should reference the 2000XJ information, but the rest of the stuff would be for the actual MJ chassis, which is from 1989. Here are the results in place. I did have to do something a bit unusual for my emissions sticker because the engine compartment is coated in bed liner, which a conventional sticker with pressure sensitive adhesive won't like. What I did was to attach the sticker to a sheet of thin aluminum of the same size as the sticker, and then pop rivet this assembly to the firewall in the appropriate spot. The rivets are almost unnoticeable, and thus the sticker looks OEM in appearance.

Our man in Guam is correct---an OEM one made from copper would be best. That said, they are like unicorns, so good luck. The next best choice is to go on to Rock Auto and look at all the aftermarket brands out there. I tend to try to choose heater cores from someone who has been in the aftermarket biz a while, and thus isn't just pushing out crap to make a quick buck and then fold their tent and move on. When did mine a few months ago, I chose one from Four Seasons, mainly because they have been providing aftermarket HVAC parts for a long time, and probably have at least decent suppliers for their cores and evaporators.

DO NOT USE URETHANE. Urethane is harmful to acrylic lenses. I did a bunch of research on this before I redid my taillights, and my initial plan was to use urethane, since I have experience with it as a retired engineer. Once I found MULTIPLE sources that said that urethanes and acrylics don't mix, I dropped it from my list of candidates for bonding the lenses. I would steer away from many RTV's due to UV stability issues. I live in AZ, and the sun here can be IMPRESSIVELY strong. That would make me worry about RTV longevity when exposed regularly to strong sunlight. (You should see my treated lumber trellises for the vines in my back yard...8 years old and due for replacement from sunlight damage.)

I used RTV, and found it bonded VERY poorly to the acrylic lens. I documented this in my write up. Based on my experience, I do NOT recommend RTV silicones for this application.

HERE YOU GO. MJ Taillight Restoration

I did a write-up a few months ago r on restoring MJ tail lights using née Key Parts lenses, and described the adhesive i used that is much more modern than the junky OEM stuff.

Used compressors are a crap shoot, and for that reason, I would consider them a last resort. reman compressors, in my experience, are worthless. I am 3 for 3 with failures of those. I HIGHLY recommend a new compressor if you decide you need one.

Given that 4.0 heads of that variation are a dime a dozen in junkyards, why spend the money to resurrect a cracked head? Remember, repairing cracked heads is a skill that not every shop is equally competent in performing.

If you purge the manifold, contamination is nil. Pressures for R12 and R134a are such that one set of gauges are suitable for both.

The guages will be the same. What will be different will be the fittings on the hoses that connect to the fill ports on the vehicle. New fittings can be obtained to attach to the existing hoses. A new can tap valve is needed to connect a R134a can to the fill hose, and any auto parts store will have that.

It is considered good practice to replace the accumulator whenever the system is open to the atmosphere for any length of time, as yours will be. The accumulator contains a desiccant to trap any moisture left in the system, and when left open for long periods, that desiccant is trashed by that uncontrolled exposure to moisture. Accumulators are not very expensive, and a new one will insure best AC performance.

Keep in mind that if you are pulling parts from a junkyard, those parts are probably close to the same age as the ones currently in your vehicle. That means any refrigerant hoses and the blower motor are in a donor vehicle are aged. If I was re-doing the AC system in your vehicle, I would inspect my existing hoses for any signs of cracking or chafing, and replace with new as needed. For reasons I explain below, I would replace the blower motor and the blower motor resistor with NEW parts while I was at it. (The motors tend to draw more current as they age, and this taxes the blower motor switch more heavily, and possibly can cause it to MELT. There have been photos of this phenomenon on this board before.)

That is fine, buy how do you intend to get the same evaporator into the "good" heater box in your vehicle? I assume you are not planning on cutting THAT firewall, are you?

Yeah, you don't want to use R12 anymore unless you have NO other choice. R12 is HORRIBLY expensive, (typically between $30 and $50 for a 12 ounce can that most DIY guys would use). Also, you cannot buy R12 at normal retail outlets. You have to resort to the "gray" market on eBay. On the other hand, R134a is about $12 for a 12 ounce can at almost any auto parts store. Since you are already planning on disassembling your AC system to work on the heater box, the differential cost to do the conversion is going to be: 1. the two R134a adapter fittings that attach to existing R12 filling ports on the high and low pressure lines. (Figure this is less than $20) 2. the appropriate amount R134a compatible refrigerant oil (Again, that's $10) All the other things I described (accumulator and o-rings) you are going to need REGARDLESS of whether you convert to the more modern refrigerant. So if you spend about $30 up front, you will spend less than $24 to fill your system with R134a. (Assuming two 12 ounce cans to fill the system) If you keep with the R12, you will spend $80 to fill your system with R12. (again assuming two 12 ounce cans to fill the system) And if a leak shows up during your fill, then you are back to spending much more for any further refrigerant you will need if you stay with R12. As I Pete said, it makes little sense, economically, to stay with R12 on an MJ.

If your dad has refrigeration vacuum pump and a charging manifold (the 3 gauges and hoses), you can recharge the system yourself. Does you dad have experience in evacuating/filling auto AC systems?

I assume you are transplanting the 97+ interior from an XJ into your MJ, correct? If you are going with parts transplanted from an XJ that had an R134a system, you will need to get the AC compressor from that system as well, and all the various AC lines. The expansion valve used on the R134a systems is totally different than that used on the old R12 system (better, actually), and thus the old lines and compressor would not be compatible with the newer evaporator and expansion valve.

That is correct. I would cover the hoses with either tape or plastic baggies. (If you use tape, clean any adhesive off when you install the new o-rings.) Be sure to lubricate the new o-rings with refrigerant oil when you install them.