Eagle

And you know that your valves have the triple grooves? If not, you should be good to go.

Sounds like a clogged catalytic converter. Does the engine make the noise when revved at idle? Usually such noises go away at higher RPM because the oil pressure is up. And the oil pressure gauge has numbers. "Low" is meaningless. What numbers are you reading? All too often people post that their idle oil pressure is "low," then when we point out that the factory spec for idle oil pressure is 13 psi it turns out their oil pressure isn't so bad after all.

What does "popping up" mean? Did you use new attaching hardware, including new hold-down pins and springs? Are you certain that the spring retainer cups are properly seated at 90-degrees to the head of the pin? If you bought new hardware, are you sure it's for a Dana 35? The D35 brakes are 10"x1.75". The D44 brakes are 10"x2.5". Hold down pins for the D44 brakes are too long for the D35.

Valves, or valve springs? I can't imagine any reason to replace the valves, but most cam kits either call for or require new springs, new keepers (retainers), and new seals.

Fram filters are notorious for causing rod knock and low oil pressure in the 4.0L engine.

I can't visualize what this means. And the Bendix drum brakes that AMC used are (IMHO) infitely easier to work on than the accursed 9-inch Chrysler drum brakes. Post a photo of where the front shoe won't seat.

Absolutely not. Use the temp sensor hole for venting the back of the block when filling. Once that's done (cold), replace the sensor and fill the bottle to the halfway mark (the notch in the post). Start the engine, leave the cap off the bottle, let it idle until it starts to bubble. Then shut it off. CAUTION! After you shut it off, the bottle will initially regurgitate hot coolant -- be careful you don't get scaled. Watch the bottle from a safe distance. After a couple/few minutes, you'll see the fluid level suddenly start to be sucked down. As that happens, add more coolant to replace the air that has been displaced. I usually have to do that two or three cycles before the system is properly bled.

How many miles on the '90 engine? What's the oil pressure at idle and at highway speed?

One other thing after all that cooling system work: Now that you've been driving it, check the coolant level. If it's not pretty close to being filled, coolant doesn't flow through the heater core.

Any Comanche that runs and isn't a bucket of rust is worth $1000. In the rust belt states, people want twice that for vehicles I would never consider buying except for scrap. 350,000 is getting up there in miles for a 4.0L, but if the previous owner changed the oil regularly it should still have life left in it. If it really is a 1988 and if it really has a six-cylinder engine, it's a Jeep 4.0L in-line six (unless it has been changed), and the best replacement is another Jeep 4.0L engine. The ones from 1987 through 1990 all have the same injection and ignition system and the same ECU as the '88. Cherokees and Comanches are identical under the hood and dashboard, which is why XJs are good donor vehicles for engines and drive train for the MJ. In 1991 Jeep changed over to a different ignition, injection and computer system. You can use the later engines, but it means either changing the entire wiring harness, or modifying the newer engine to work with the 1988 electrics. If you're into rebuilding the engine yourself, it can be bored out and rebuilt using the crankshaft from the older Jeep 4.2L I-6 to bring the displacement up to 4.5L to 4.7L (depending on how much you bore it). At 350,000+ miles, a rebuild will probably mean boring and new pistols anyway, so you might as well go for it. A LOT of people have done this, and there's a lot of information available.

This may help: https://spreadsheets.google.com/pub?hl=en&hl=en&key=0AvuGamS7bzt-dHJxYy1QajhuVUFUbUVDUWdiZnVFbmc&output=html

No. The plastic bottle is a pressure bottle. Nothing should escape or "bleed out." To prevent rupturing the bottle under pressure, the bottle is filled to the halfway mark when the system is cold. The air in the bottle compresses under heat, allowing the coolant to expand. How high are you filling the bottle? If you have been filling it -- there's your problem.

Fuse(s)? A '95 would be an electronic speedometer if you swapped everything over from the donor vehicle. There's a fuse for that. There's also a fuse for the TCU, and if that fuse is pulled you can shift it manually but you only get three gears instead of four. Or maybe the speed sensor in the transfer case is stripped (the gear is plastic) so the whole system just isn't getting any speed information.

No, it isn't possible. I don't know about any Marchal "agreement," but my sister-in-law had an early 80s Eagle SX-4 and that came from the factory with Marchals. There's a reason why the Jeep literature named Marchal lights by name -- that's what they were using, and back then the Marchal name was a premium brand. I very much suspect that anything else was either dealer installed or aftermarket.

Where are you seeing "ROL"? In 1987 through February of 1988 AMC/Jeep was in partnership with Renault, a French company. Marchal is/was a French company. AMC used ONLY Marchal for fog lights on all their vehicles during that time period. The off-road lights on the rollbar of my '87 MJ are KC Daylighters, and I'm certain they are factory equipment. I'm only the second owner, and the original owner was an older gentleman who just drove it, he didn't modify anything.

3.07s with 235/75-15 tires is very workable -- it's only one tire size larger than what came stock on most of the late XJs. (Early XJs, even with the 4.0L, mostly had 205/75s or 215/75s.) Where you will be wanting more gear is when you move up to 31" tires. Can you drive on 31s with 3.07 gears? Yes, you can. I currently have the 31s from my '88 MJ on my stock '88 XJ with 3.07s. I can drive it, but it's doggy, and I am pretty well convinced that it actually hurts my fuel economy.

With 4.10s and 31 inch tires your city mileage will probably be better than what you get now. Highway mileage will depend on how heavy your foot is. My '88 with 31s and 3.73 gears got 19 MPG highway.

Yes, I believe it will be hot. It's 12 volts from (through) the gauge to the sender, and the wire grounds to the block through the sender. If the wire weren't hot, that would mean the system is sending 12-volts through the block and out through the oil sender to the wire. 1990, so it's a Renix and has the "old" wiring. The resistance of the oil pressure sender varies from 0 to 88 ohms, with 0 ohms (no resistance) being 0 oil pressure, and 88 ohms being max (80 psi). A quick test is to take the wire off the sender, with the key on, and ground the wire directly to the block. That will be zero ohms of resistance, and the gauge should then read zero. Remove the wire and the gauge should swing all the way to the opposite end, to or beyond 80 psi. If the gauge doesn't read zero when the wire is grounded directly to the block, you have an open circuit somewhere between the sender and the gauge. If it does go to zero when you ground the wire, most likely the sender is faulty.

How's your ground from the engine block to the body?

My rule of thumb is 3.73s for 30" tires, 4.10s for 31" tires, 4.56s for 32" tires, and 4.88s for anything larger than 32". For reference, I ran my '88 SWB with 31s and 3.73 gears. The overall final drive ratio (as determined by road speed per 1000 RPM) was exactly the same as my wife's bone stock XJ 4.0L with automatic.

The wiring is already in place for the tach to work. The fuel gauge and voltmeter should also work with no changes necessary.

The tachometer will work, but the temperature and oil pressure gauges won't. The idiot light senders for those are simple ON/OFF switches. You need to change the sensors to the ones for gauges, which aren't switches but variable resistance senders. No wiring is needed, just swap the sensors.

Photobucket. Flickr. Tinypics. Image Shack. All free photo hosting sites. Heck, I think even Kodak may now offer free photo hosting.

1. You don't have an AX15. It was only used behind the 4.0L from mid-1989 on. You have an AX5 or possibly a T-5. 2. No cutting of fenders is necessary to fit a 4.0L into an '86, but cutting and/or reshaping of the firewall might be necessary. Of course, since you have the '89 donor vehicle, you could graft in the '89 firewall. 3. As to the XJ with the rusty frame -- the XJ is unibody. It doesn't have a frame.

If you are really going to remove the a/c, do it right and find the factory idler pulley and bracket. Or do as suggested above and convert the compressor to on-board air.