brucecooner

Have poked at a few more things around this mystery... I did a compression check and the numbers look pretty good (130's), so I don't feel like there's any upward pressure from the cylinders. I pulled the rear line off and blew through it and verified it's clear. I also pulled the back end of the rear line from the valve cover with the engine running, and I could actually hear it pulling air. It stuck to the end of my finger pretty good too. Then I pulled the front line from where it connects to the breather box and it had a verrry slight suction to it. I'm not sure how much it's supposed to have but the loop seemed to be working, if a bit weak. And I guess the pressures could shift and change as I drive. My "pull the back line" test told me the intake was sucking on that line, but it did not tell me anything about the state of the elbow fitting that plugs into the top of the valve cover. I've heard those CCV fittings can get blocked or produce low flow situations, which might be a problem. I'm not sure if that's a removable piece or not without pulling the cover though. At this point, after verifying that slight suction at the breather itself, I'm a little stumped as to what's pushing oil out. I do need to replace the valve cover gasket, at which point I plan to do the shortened pickup mod, and might replace the CCV fittings at that point, or just research and do one of the upgrades listed by 75sv1. Rats shouldn't get a chance to next in this breather box, because HOPEFULLY I can get enough issues sorted that it'll get driven year round. At the rate I'm going though, it might become a wildlife sanctuary before I get it very far.

I've heard that about consistent pressure too, but it wasn't on my mind. All the numbers were within about 10 PSI low to high (assuming #2 gives a similar reading). Now to try and answer the question of how oil is getting into the breather if compression is not getting past the valves.

My first ever compression check was uneventful but interesting. I started by looking up where the fuel pump relay was (second from the rear), and pulling that relay and the coil wire. THEN I remembered you're supposed to let the engine warm up first. I took the chance to scrub and OxGard the relay contacts, plugged things back up and started it up to let it warm. The check itself is straightforward enough. Take out a plug, screw in the tester, push the gas all the way down and turn it over a few times. The videos I watched to study conflicted with each other whether to take all the plugs out or leave them in. I split the difference and left one of the next plugs out as I went down the line. But I got some numbers (took three readings on each cylinder), and the numbers I got were consistent on each cylinder, and they look pretty good. It showed in the middle 130's on 3 through 6. Daylight ran out before I was done, and I couldn't even think about doing whatever it takes to get #2 out. That thing is BURIED. Number one was a steady 118, but that one is pretty well guarded behind the AC compressor and I know I didn't have the fitting snugged in there. I got out my extended needle nose and grabbed it best I could to tighten it down a wee bit. Then #1 read a steady 128. I feel like if I had been able to properly tighten the fitting it would have gone up a bit. So I guess that's that. I've heard you're looking for 130 or better so If I did it right, it shows readings right around where they should be. I feel like parts are pretty well snuggled together inside, and the head gasket is in decent shape. Plugged everything back together and it was a rough-ish start but it settled right in to idle. Strangely enough the weird surging-suring-surging idle was considerably reduced this evening. It does have a distinctly rough moment that reoccurs every few seconds. The engine shakes just a little when it happens. It's making some concerning noises now though, and now sounds like it has an exhaust leak? Could swear that's new, so I'm wondering now if the exhaust manifold has cracked... Old jeep ownership is certainly an adventure, whether you take them offroad or not.

For some reason I perceived that the master cylinder was much higher than the pedal on the firewall. I was confused because under the hood I'm looking at the reservoir, but the cylinder must be below the reservoir, and the pedal is attached to the cylinder. I learn something every day. I wonder if leaky seals in the cylinder might be the cause of the lack of disengagement. If too much fluid bypasses the pushy part, maybe the clutch doesn't get the message. Can the master cylinder be tested somehow? I sense a pressure test somewhere might be the answer.

Oh man, tell me about it. It's thrown enough stuff at me in a short span of time that I've avoided messing with it the past week or so, out of a mix of frustration and fear. I've got a list of issues somewhere in my thread here that seems to periodically jump in size before I manage to get a single thing addressed. Then when I can't seem to fix anything I feel like I'm just wasting the time of people trying to help and I get more frustrated with myself. I don't want to drive it until I know what's up with the clutch so it's just been sitting in the driveway. I don't want it to just sit there though, so I fired it up the other day to let it warm up and it started on the first crank, then settled right away into its weird surging idle. I've noticed now that it sounds like it's ticking at the top end and maybe slapping at the bottom end. I could have sworn those noises weren't there before, a couple more new features I've discovered I guess. There's a chunk of me that feels I'll never get it running really well. But it has run fine, doesn't feel low on power, has gotten 20 mpg on the dot in the last 100 miles I drove it before the clutch decided to aggravate me. Anyway, I borrowed a compression tester from the parts store today, going to have a go at it tomorrow mostly out of curiosity. I guess I felt I didn't have enough stuff to worry about lol. Old Jeeps are weird. It seems like they can have all sorts of known issues and still run fine.

I'll pump it again when I'm back in the cab and check the rammy part for fluid. I was noticing you could see fluid in the opening of the seal at the end, some is definitely leaking out here. I wonder if that's a sign of bad seals in the, whatever the pedal-pumpy thing is called, which might mean it's not pushing a sufficient amount of fluid to the slave(?) cylinder. I bet that thing is a complete pain to access and change, too.

Thanks for the detailed info gogmorgo. I love knowing how subsystems work. There are some useful videos out there showing where all the lines around a 4.0 start and end, but they don't give any context, and I like to know what things do. I've though of taking images of the engine and trying to build maps of the various lines' endpoints with some sort of attached legend explaining their function. Then another image highlighting the various sensors, another for other bits, etc. I bet somebody's already made them. Anyway, from your description it sounds like if the manifold line were blocked, it would push air into the breather, so I definitely need to pull the manifold line and check for blockage. If that's clear, I need to get on that compression check I've been thinking about, maybe the oil's getting pushed into the box by leaky valves. I've heard a paper filter is a little bit better at catching dust than the reusable ones, and living in Arizona we got looooots of dust. If I can get this figured out I'll probably switch. Thanks again!

I gave it a bunch of pumps then waited... The cylinder on the pedal looks pretty clean. A little fluid on the ram, but nothing dripping from the cylinder inside. I crawled around under it with a flashlight, and didn't see any fluid on the lines that go into or out of the front of the transmission. No fluid between engine and transmission. The dust cover plate is still dry. There is that leak behind the dust cover plate, but that is oil and not brake fluid. I'm pretty okay with a new clutch at 190K. I like the idea of knowing its exact age. As always, thanks for the help.

It does seem to grip okay once it's going, it's the disengaging that ain't happy. Is there a way to check if the fluid is going where it's supposed to? But it looks Luk is the preferred brand around here. I see the "heavy duty" jobs with increased grip and all, and I do plan on climbing a few hills. But at the same time I don't want to shock the tranny.

While messing around near the dipstick this evening, I noticed a pair of lines with what look like brass elbow fittings at the end that appear over the top of the bell housing, but don't connect to anything. I pressed my finger against the end of them, they are open and very, very grimy inside. I was wondering if these are only used with an automatic transmission.

I actually found time to do the first tip this evening, the major grounds near the dipstick. I also went after the other end of the line that goes from that stud to the inner fender. https://comancheclub.com/topic/68912-bruce-has-to-enroll-at-mj-academy/?do=findComment&comment=723322 Afterward I got in it and started it to make sure I hadn't bricked it, and once it idled down it seemed the dips in the RPM were going lower than they did before. The RPM would even dip low enough to seem like it was going to stall, which it hasn't been doing. I've also noted that if I blip the throttle, when it comes down it'll do the really low RPM thing and act like it wants to stall then too. May be related, may not be. I was just fiddling around on the passenger side of the block tonight, but is it possible I knocked something else loose, or maybe I bumped a hose and made the leak worse?

I wouldn't know, not a mechanic here. cruiser's been helping with this in another thread, and he thought it was too early to blame the idle air control (is that the same thing?). My MJ does have AC, but I've rarely run it so far. I do most driving in the evening away from town, and leave the AC off and the windows down. The last person to mess with the comfort controls in the cab was my wife though. And I haven't checked them since she did. She might have just turned the blower off and left the AC on, but no cold air's coming out of the vents so I'm pretty sure it's off. I'll check next time I'm in the cab though.

I took my MJ out for a pleasure cruise yesterday evening, and when I was close to being home the clutch decided it no longer wanted to disengage. The rest of my drive involved some intense negotiation with the pedal and shifter. I checked the fluid in what I think is the master cylinder this evening, and it shows to be plenty full. This did make me suspicious that the fluid coming out of the bell housing was actually clutch fluid but upon closer inspection nope, it feels like oil. So the hunt for that leak will continue... It failed to disengage a couple of times on last week's drive too, but the condition wasn't persistent. Both times it's happened, it was only after a couple dozen miles. It could be something you have to drive a while to cause, but I can't say that for sure because it's a new behavior. If anyone has other suspects to interrogate that might point to the issue, I'd be interested to hear about 'em. I'm hoping this isn't a transmission issue. As far as I know this is the original clutch, so at 190K it seems normal it could decide its clutching days are done. I don't have the space, skill, nor time to go after replacing a clutch, but thanks to a fellow local MJ owner I've got a bead on a shop that specializes in AMC products. I called them up and talked to them a couple of weeks ago, feeling them out on a few potential things that I thought might come up on mine. The owner seemed nice and knowledgeable. A few things I mentioned he said were easy enough for me to do without even bringing it in. but I brought up a clutch (not knowing mine was about to lay down on me) and he recommended a Center Force dual friction job. Upon research, this just sounds like a performance oriented clutch meant for competition. That shop works on Jeeps, but they build a lot of big block street bruisers, so maybe that's why a comp clutch is his preference. I surely don't need anything competition rated though. I'd actually be afraid of sending too much power too quickly through the old Peugot gearbox. What I'm most interested in is not performance but durability and reliability, boring stuff like that. In the other clutch thread Luk was spoken of very highly. Is that the goto brand for most guys? They last pretty well? I hope to be doing some light offroading with this thing eventually (nothing intense, just some mildly rocky stuff here in AZ). Is there a style of clutch more suited to offroad use?

I've been wanting to start in on cruiser's tips, but life and other stuff keeps keeping me away. But today I finally did one. Probably the easiest one, but you gotta start somewhere. I had raised the hood late this afternoon to check on my clutch fluid level (it's fine, I guess the problem with my clutch is actually the clutch). But while I had it up I took a look at the major ground stud near the dipstick, which I knew was among cruiser's first spots to scratch. I looked to the west. The sun was low, probably too low to start a project, but without thinking about it too much I went for the socket set. I knew this whole side of the block is in grimy shape, thanks to all the ongoing oil seeps. (I had already removed the nut before taking this shot) I was alarmed that the interior chime went off when the innermost lead lost contact, but I went about my business anyway. I hit them with contact cleaner, probably to no effect, but I wire brushed them and even got after it with some sandpaper to get them somewhat shiny. Hit them with OxGard and a wire brush to work it in (I hope), and put it back together. It did seem a bit shinier after. I noticed that one of these cables looped went toward the firewall, looped back around the power box(?), and attached to a nut on the inner fender. And where it attached the nuts actually looked a bit rusty? Or not rusty but, I don't know. They looked weird. I was suspicious this was actually grounding anything, so I pulled the outer nut, lead, and washers. Everything here had a dark layer of, something on them. I sanded stuff up best I could to get some shiny spots and (barely) got it all back together. This picture is the two lock washers that surround the lead after I sanded them down a little to show at least some bare metal. The left one looks wet because I just put OxGard on it. Whew. Nothing here was difficult but hopefully this puts me ahead of the game a wee bit. I cleaned myself up, went back out, started it up and.... ...after it idled back down, it seems my inconsistent idle is a bit worse now. Huh. I wonder if I knocked a hose loose in my fumbling around under there. Oh well, I'll take my small wins where I can.

If you grew up around mesquite trees I was going to ask "Arizona or Texas?", but the answer looks like it's right there in your name. :)

Thanks everyone! I actually had a small win in the cab today. The interior lights weren't turning on when I opened the doors. My mind started racing around thinking about wiring and switches and everything, and completely skipping over the bulbs. Spoiler alert, the bulbs weren't the problem. The problem was way closer to home than that. I carefully pried off the driver's side light fixture, unplugged the fixture, and figured out how to pull the bulb out. The bulb has a pattern embossed on it that made it hard to see if there even was a filament, but the tester showed continuity. I went back to the plug, which interestingly had one red and two black wires, so I figured duh, it has more than one way to come on. Crucially, either of the black wires across the red showed 12 volts with the door open. Aha, so it wasn't a circuit issue. This just left the fixture, which I took inside and began looking over very closely. I was immediately confused that, with a tested bulb in it, there was zero continuity between the middle plug lead and the other end of the bulb. I looked for a way to disassemble the lens from fixture so I could trace where the leads went, taking great care not to break some irreplaceable piece of 30 year old plastic. It had a really weird design. At one end the bulb sat in a little round cradle that I found out had NO connection to either of the black-plug leads. And then the light IN MY HEAD came on, and I figured out that the entire fixture is a rocker switch. The contact that looks like a cradle is actually a cradle, that holds the switch in the middle position (which is OFF), but serves no electrical purpose despite looking like it does. I rocked the lens to one side with a satisfying click, and then the tester beeped on the leads. Durrrr, me no need read instruction manual that come with truck. I figured since I had both fixtures out now, I might as well clean up the touchy bits with some contact cleaner doused Q-tips. They were pretty grimy. I cleaned up every part that contacted another part, and put some oxgard on the plug leads for practice for when I go after all the ground contacts under the hood. Plugged them back into the truck, flipped them to the up position, opened the door and lo and behold, they were working just fine the whole time. Turned out the problem with the lights was just operator error. In my defense though, the lens had "Made in France" molded into it, and my French is really rusty.

Between work and weather (Phoenix summers!) and other obligations I've had little time to raise the hood. I did have a small win today. The interior lights weren't coming on, but with a multimeter and some fiddling about, I learned that I don't know how to work a light switch (or read a user's manual, I guess). I've acquired some OxGard though (I shopped around to make sure I get OX-100-B instead of OX-400-B, which probably makes no difference but your site showed a picture of OX-100-B, and I'm a stickler when it comes to following instructions), so cleaning some grounds is up next on my list, soon as I spray the grime off the passenger side of the block. Regarding that idle irregularity, should I be suspicious of the Idle Air Control thingy on the throttle body?

Yes sir! Other than that slow start it actually runs very nice. Well, it's got that weird surging idle. And it needs a new valve cover gasket, and other normal old Jeep stuff. But overall it seems to be doing well for a 30+ year old vehicle.

Okay, I pulled the dipstick and took a look. It...looks like oil. Clearly changed recently. I got some between my fingers and it does not feel "liquidy" at all, not like lighter weight fluids. It is definitely forming a coating between my fingers that keeps them apart as I glide my fingertips over each other. It is slightly tacky when I pry them apart. As far as I can tell, the oil feels normal. The oil pressure according to the gauge goes from upper 20's at idle to 40 on the nose on the highway. Maybe not as high as I've heard but seems within operating ranges. Not sure if that would be a reliable indicator of fouling oil anyway. When it's being hard to start, a mild pump on the accelerator helps. Sometimes I'll smell gas after it starts, like maybe I overdid it. But would needing a shot of fuel indicate some other issue?

Is there a recommended brand or style to use or avoid? I'm not interested in anything platinum, trip-tip, etc. Whatever gets the job done..

I figured I'd get eyes on some of the spark plugs this afternoon, sometimes they can tell you a story. I started at random, with #3, mostly because it was easiest to get to. It, and #4, looked mostly new on the outside. Inside, the nub didn't show any wear, though the darkness at the base of the threads caught my eye. Is it getting scorched or something? Number six was a different story. This guy is obviously taking the brunt of the leaking valve cover's oil, but the nub here was what really caught my eye. It's completely out of shape, so much that part of me wonders if it's even the same brand of spark plug. Like a dingus, I didn't even think to check the brand on the side of the body, durrrr. Anyway, is it possible for some spark plugs to wear so differently from others? Or is it possible somebody ran out of spark plugs before they got to #6, or just didn't bother changing it last time for some other reason? At any rate, I'm leaning toward all new plugs, so I can have a firm date of install and just so I can finally get a small win in the mechanical department. I've heard you want copper ones? But then there's that number two plug. On my '88 with A/C that thing is BURIED behind the compressor and a big honkin' radiator hose that is itself protected by a strong metal bracket. And, it appears that the metal bracket is piggybacked in with a bolt that holds on the back of the compressor. The number one I could at least see, and probably get a socket to. But can #2 be removed without draining the coolant and detaching hoses? I looked for videos on 4.0 spark plug removal/changes, but none of them had a similar configuration up at the front.

Dang it, I didn't see your reply in time for my explorations under the hood this afternoon. I'll check the feel of the oil out next time it's up. I seem to remember that good oil has a slight tackiness to it, you should feel it holding your fingers together ever so slightly before they come apart. I drove it to the gas station this evening, then around the countryside a bit. When I got it back in the driveway and turned the motor off, I waited a few seconds and turned the key again. I figured restarting it right away, before fuel has time to drain out of the rail, might be a good test of your theory. It started right up, no hesitation and no help needed. So it's not strictly a warm engine behavior, looks like it has to sit a while before you get the difficult start.

I removed the line this afternoon and checked it out. No leaks I could find, and I could blow through it so it wasn't blocked. I pulled and tugged at fittings looking for loose lines, and ran my finger along the underside of most of the lines under the hood, everything is actually very clean and smooth. I have a can of non-chlorinated brake cleaner, maybe it's time to spritz it at various...fittings? Maybe I shoot it at the intake seam?

Thanks. And thanks cruiser for the tip. A new valve cover gasket is definitely on my list, and I might as well shorten the flute tubes while I'm at it.

I removed the breather box this evening to have a go at the intake manifold bolts (didn't even get close), which led me to interesting discovery. Oil is getting into the breather box somehow. I couldn't tell for sure if it's all coming in through the, uh, fat line or the skinny lines that plug into the back of the box. Maybe both. On the inside of the box that spongey material that covers the skinny line inlets is pretty gooped up with oil, but there's evidence of it coming in through the fat line inlet just below as well. Or maybe it's coming in through one and out the other. It's certainly made a mess in the bottom of the box, keeping that bolt nice and lubricated I guess. Looks like a previous owner parked near a mesquite tree. And the filter is pretty well soaked. Holding it up to the sun... Rich deposits of oil infused dirt and gunk on the bottom where it's soaked through. I cleaned the box up best I could before reassembly and banged the filter against the side of the trash can to get the solid gunk off of there but a new one is in order. I had noticed faint traces of oil at the beginning of the air inlet connected to the box, but the throttle body itself didn't appear to be coated. I worry that some of this is evaporating when the box gets hot, and going into the intake though. It looks like a new filter is in order so first question, what's the best air intake filter to get? The one that's in it seems rather high quality in nature. Good material, looks like it's even covered with a metal mesh, but the media seems pretty well choked up with oil. It might be a clean and reuse job, I've heard they exist but I've never messed with them. Second question, what is this all this oil in the breather box a sign of? PCV issue? If not that I bet it involves some other acronym I'll have to look up. Or is this just another creative way the old 4.0 uses oil?