The Beautiful Jeep Cherokee That Blew Up After I Sold It To A Nice Lady Is Truly The Jeep From Hell

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I should have been in Chicago on Sunday, but instead I sit utterly defeated here at my house in Troy, Michigan. I’m covered in oil and coolant; lack of sleep has sprouted saggy bags under my eyes, which now stare blankly into this screen as my fingers bang out the words you’re reading with little input from my now barely-functioning brain. I have been defeated. All day Saturday and Sunday — the entirety of my weekend — involved me, a former Jeep cooling system engineer, being absolutely decimated by an overheating Jeep Cherokee XJ. I’m thoroughly annoyed, I’m thoroughly tired, and the buyer of this Jeep Cherokee may be thoroughly screwed.

I cannot even think back to the last weekend where I wasn’t fixing something. Truly, I think at least 90 percent of my non-travel weekends between age 24 and 31 (well, in two months) have involved wrenching on a shitbox. That’s seven years of my youth occupied by the ol’ wrench.

You’d think that the result of a youth spent with machines and not people my age would be an ability to fix damn near anything. And every now and then, like when I — even encumbered by a case of trenchfoot — revived a 1958 Willys FC that had sat for decades, I do begin to wonder if I’m hot shit with a toolset. But more often than not, any budding cockiness is swiftly crushed by the wrenching gods before it ever sprouts; that’s what happened this weekend.

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It was a simple cylinder head job; I’d conducted the job four times prior, so I wasn’t anticipating any trouble from the beautiful 1991 Jeep Cherokee five-speed that I’d sold to the family that had ordered the Jeep from the factory way back in 1990. Sadly, 20 minutes after the buyer left with the title (no money has exchanged hands, she was going to wire it to me) to head back to Chicago, she told me the Jeep had overheated.

It was a tough call to get, because the amount of work I’d done to this XJ since going through hell to buy it back in 2018 — just to get it into selling shape — is shocking; The fact that the Jeep still isn’t finished made my heart sink. I was inching towards freedom; soon I’d no longer be weighed down physically and emotionally by American iron, but the AMC gods thought differently, and shoved the 9/16 swivel-head ratchet wrench right back into my hand.

You’ll understand why I was so bummed when you look at this list of repairs I made prior to the sale in April:

  • Replaced front left fender (which I had professionally painted)
  • Replaced front left fender flare (which I had professionally painted)
  • Replaced front left fender liner
  • Replaced front bumper (which I had professionally painted)
  • Replaced rear bumper (which I had professionally painted)
  • Replaced front axle
  • Replaced front axle u-joints
  • Replaced front ball joints
  • Replaced steering tie rod ends
  • Replaced steering drag link
  • Replaced steering intermediate shaft
  • Replaced steering box
  • Replaced control arm bushings on front axle
  • Replaced front axle seals
  • Replaced front axle disconnect motor
  • Replaced front wheel bearings
  • Replaced front brake pads
  • Replaced front left wheel
  • Replaced all four tires
  • Replaced all four shocks
  • Replaced rear leaf springs
  • Replaced driver’s seat
  • Replaced driver’s door check-strap
  • Fixed rear hatch interior trim
  • Replaced front windshield wiper motor/transmission
  • Replaced engine computer
  • Replaced radio

Holy crap that’s a lot of work, and for what? So I could store the vehicle (which I considered the most perfect Jeep ever made when I bought it, with plans to keep it forever) for four years and only drive it a total of maybe 50 miles.

This XJ Cherokee ownership experience has been a failure in every way. I haven’t driven the Jeep, I’ve spent years fixing it, and once I finally had all of those repairs done and I thought I could finally part ways with this mechanical menace that had haunted me for far too long, the XJ decided to come right back and kick me one last time. And this time I’d be on the receiving end of the most painful blow yet.

After the Jeep overheated 20 minutes into the buyer’s (that’s Tracy) drive, she drove back in the car she’d piloted to Michigan, and I’d agreed to mend the engine. I heard a fairly loud knocking sound coming from the bottom of the motor, but once I learned that this was just the water pump banging around a bad bearing, I felt at ease. I could replace a water pump. Unfortunately, the Jeep wasn’t running properly; a compression check confirmed that the cylinder head had failed, and a machine shop later confirmed that it had cracked.

That brought me to this past weekend.

I had a freshly-shaved cylinder head ready to go, along with a new cylinder head gasket, new head bolts, a new water pump, a new thermostat, and a bunch of other replacement parts that typically accompany a head-job. After lapping the valves and swapping the valve stem seals for good measure, I threw the new head gasket onto the cleaned-off deck:

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Then I maneuvered the absurdly heavy cylinder head onto the engine. I’ll admit that I didn’t get it aligned perfectly, and had to slide both the head on top of the gasket as well as the gasket on top of the deck. But the surfaces were smooth, and everything slid easily until I could get all my head bolts tightened up.

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There’s a specific sequence one has to follow when tightening cylinder head bolts. It’s all about making sure that the head squishes down evenly on that gasket. I followed protocol, and then fastened up a new water pump and thermostat, hooked up the intake and exhaust manifolds, bolted up the power steering pump, slid the belt back on, connected the ignition system, filled the cooling system, and did a whole bunch more to get the Jeep finally ready to fire up.

After an initial ground strap issue, the Jeep followed the request from that ignition switch in the gray Saginaw Steering column and sprung to life. The motor sounded good. So that’s it, right? I’ve fixed the failed cylinder head, now the Jeep is ready to go to a new owner.

No.

As I said before, this Jeep is a menace. You see that list of nearly 30 parts I’ve already had to replace? This XJ is going to make sure the count hits 50. It is on a mission to take the remaining scraps of my youth and turn it into busted knuckles and oily bedsheets.

Despite my new water pump, thermostat, and radiator cap, the Jeep keeps overheating, especially at a long standing idle. Steady-state conditions where I keep speeds below 50 mph, it’ll run cool seemingly indefinitely, but crank the speeds up to 75 or come to an idle, and the need whips clockwise towards the dreaded red.

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After buying a special funnel to ensure that the system was completely deaerated, I broke out a bunch of tools to determine what’s going on. The first was a radiator pressure tester. I screwed it onto my radiator, pumped the cooling system up to my radiator cap’s 13 PSI rating, and waited.

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The needle fell, indicating that I have a leak somewhere. Sadly, that leak does not appear to be external, as even a close inspection of the radiator, water pump housing, and thermostat housing shows no dripping ethylene-glycol mixture.

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The second tool I used was a “block tester” (shown on the left), which basically involves pouring a blue detection fluid into a cylinder, shoving that cylinder into the radiator, and sucking air from the cooling system through the blue fluid. If there are combustion gases in the coolant, they will turn the blue detection fluid yellow, meaning there’s a head or head gasket issue. My test fluid remained blue.

I also broke out my compression gauge, finding all cylinders to read between 100 psi and 120 psi — these are below the 120 to 150 spec, but maybe the gauge isn’t reading right. What’s more important with compression tests is consistency across all cylinders, and my engine has that, and does not burn any oil.

That brings me to the real problem: The motor does gain oil.

Yes, my oil reading on my dipstick is increasing. Between that and my lack of cooling system pressure, I suspect an internal problem. Do I have a cracked block? Did I somehow screw up my head installation? Maybe my bolts bottomed out or my gasket scuffed during installation? I don’t know the answer to these questions.

I may send an oil sample out to Blackstone Labs to have them confirm that it is indeed coolant in my oil and that I am indeed utterly screwed. Until them, I’m going to make a few other adjustments, maybe add some fuel injector cleaner to my fuel (lest I have an injector that’s leaking gas into my oil), tighten some hose clamps, and possibly thread a mechanical temperature gauge into my cylinder head for a more reliable reading.

This Jeep has been a nightmare since I bought it off that used-car lot in Indianapolis in 2018. I was lured by its beauty, its manual transmission, its awesome vent windows — but as they say, it’s what’s inside that counts, and this Jeep is rotten to the radiator core. Just yesterday while trying to suss out this cooling issue, I learned of a failed upper control arm weld, so I’ll be replacing that, too.

Have mercy Jeep gods. Let this just be a bad injector and a loose hose clamp. I don’t want to lift that heavy cylinder head off that engine. I really, really don’t. More importantly, I want to deliver Tracy a reliable Jeep; she’s in a pickle right now, as she was expecting this machine to work, and has no other car to get around. So the pressure is on.

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106 Responses

  1. Save ya a sample to Blackstone- get a business card and place a single drop of oil on the back in the center of the card. Put the card drop-side up on a cup or shot glass overnight, then inspect the back of the card the next day. Coolant will make a halo around the oil drop if it’s present.

  2. So sorry for this never ending shit show David. Now that I am old, wish that some of the stupid car/engine related shit we dealt with had never happened. Mostly because life is short, happiness is fleeting, and most of our problems are self inflicted. I know you are a Jeep brand type guy, but sometimes it’s better/easier to just move along. My fear is that if she even wants this thing when it finally gets fixed, will you spend the rest of your life dealing with the repercussions of passing it on to someone else? Some vehicles are like bad girlfriends, best to walk away and let the next poor bastard deal with the pain…Wish you luck, seriously.

    1. That was my first thought. What evidence is there of overheating other than the temperature gauge? I would measure the engine and radiator temperatures in different places with one of those handy aim and pull thermometers to see if it seems too hot.

  3. Anyone else suspect this lady “Tracy” is just David in a wig. He’s created an alter ego in an attempt to resolve the tension between the need to shrink his fleet and his compulsion to live as a Jeep nut.

  4. Ahh, the yin and yang of DT and Torch.
    Torch buys a questionable Changli just for fun and somehow ends up as a brand ambassador on the company’s marketing material.
    You buy a questionable XJ out of misguided loyalty and have single-handily become example no.1 of why to never buy an XJ.
    Meanwhile, both endeavors have resulted in much rejoicing (and, I assume, gallons of celebratory drinks and laughs) from the sellers.
    This place makes me chuckle. 🙂

  5. It’s starting to remind me of my cursed green Mitsubishi Lancer (Mirage).
    -Original engine overheated on highway so bad, that it lost compression.
    -I then imported another Lancer with a friend, from a neighboring country (Austria) for parts and swapped the engine.
    -Replacement engine overheated on highway a few weeks later.
    -Had the head rebuilt, new head gasket, new timing kit, water pump, new radiator, new hoses, new electric fan, thermostat, temp sensor, the works.
    -Replacement engine overheated on highway so bad, that it lost compression round #2.
    -I then swapped in another (junkyard) engine, new timing kit, water pump, etc.
    Guess what happened next?
    Engine overheated on highway. At this point I gave up.
    The car drove fine under 60-65 mph but the needle started going up immediately when driving faster than that. I still don’t know to this day what was wrong with it.
    All my other Mitsubishis were fantastic by the way.
    The best explanation I could come up with, is that the Green Lancer was cursed.

  6. It took me years of similar “adventures” to cure my “love” of British sports cars. I’ll never look at one again. I still loving wrenching, but the thing I want most is a pristine, rust free chassis to shove an LS into. Maybe even a Jeep, but it would have to be rust free or have a rust free aftermarket body on order.

    I enjoyed my time with rusty old British cars, most of which was wrenching on them in a garage, a driveway, or all too frequently, on the side of the road. I enjoyed the adventures, but I didn’t enjoy that time nearly as much as I would’ve enjoyed driving a more reliable vehicle.

    I love your dedication to rusty old Jeeps, but I have a feeling that before long, you will decide that driving is more important than being on your back with a tool in your hands. I have confidence that your writing will be just as great for this site, even if you never save another car from the crusher.

    Mostly, I think you need to stop idolizing your Craigslist finds, and exercise a little patience. Pick better examples. Don’t worry, they’ll still need plenty of work done on them. And finish at least one up before moving on to the next.

    1. This is the correct advice. I’ve had 4 project vehicles and the ones I’ve had the most enjoyment out of were the ones that I could drive.
      -My 1969 Scout had a rust free body (yes really, it was stored in a barn out west) and chassis but no motor. So it sat as I tinkered until I sold it since I could never afford a complete motor and related accessories.
      -My 1956 Lincoln Primere ran and drove and stopped. Was rusty to the point that if I started a teardown it would have ended up a full restoration which I could not afford. That car was fun to cruise in and get ice cream with the kids. Looked crusty but was a sweet driver.
      -My 2002 2wd Tacoma truck was rusty but drove fine. I spent 4 months over a winter repairing the entire frame. Still runs strong with 278K and does lots of work, autocross and more. My boys learned to weld on that truck.
      My 1993 Honda Del Sol is a true basket case. Not much works and it’s rusted and ugly. But for the local autocross course it’s fine and cheap. Fun with the top off for short trips. But there is no point putting money into it due to the horrible condition I got it in and I’ll probably let it go soon. It seems to have been put together from a scrap shell and rough junkyard parts.

    2. I am slowly starting to feel this way about my eternal project car, a 1972 VW Super Beetle. I’ve had it since I was 11, and I’m 29 now, so it’s not like I’m going to get rid of it. It’s been a running, driving project for most of the time, excluding the cheap repaint I had done in high school and the engine rebuild I did a few years back. I love doing my own work…but I think I’m going to draw the line at welding. It has extensive rust, enough to make David proud. It’s probably safe enough for just driving around town, which is all I do with it.

      Honestly, I just want to drive the damn thing. I’m tired of replacing worn out 50 year old parts, or trying to get just a little more life out of some of them. If I had the money now, I’d gladly pay someone to put everything else right on the car, namely the rust. I wouldn’t mind adjusting those awful drum brakes if it wasn’t an experience that involved getting showered in rust and filth. The yearly tune up wouldn’t be so bad if I didn’t have to get under my car and look at the rust that’s slowly eating it.

      People tell me that the Beetle must be easier to work on than late-model cars. But I’ll take a late model car over the Beetle most of the time. Because I’m not battling RUST and age-related failures that come from driving a car about 40 years past it’s intended service life. So what am I doing? Saving money, and halfway hoping my father decides to help me out with the rest of the restoration when he retires.

    3. Very well said. Something magical happens when any of these three happen. I think it mostly has to do with more appreciation for the value of your limited time:
      1. You get married
      2. You have children
      3. You cross into your 30’s

  7. As you well know David, I have an endless capacity for idiotic questions. Today’s is, did you gain oil after it got warm? I have a TDI wherein every time I change the oil and refill it right to the dipstick mark, as soon as the oil gets good and hot I get a reduce oil level warning. It’s clearly expanding enough with heat to trip the warning. You may not actually be gaining oil. End of dumb question 1.

    Dumb question number 2 is, could the old water pump have thrown a chunk(s) of metal which are blocking flow? I don’t know if the flow direction goes from the pump to the radiator or to the block, but if it goes to the radiator, then I’d just buy a new radiator and swap it out. You’ve replaced just about everything else. It could also have sprung a pinhole leak and if it’s near the top of the radiator, you’ll never know it. If the flow goes to the block, then maybe use a bore camera to look for blockages.

    Just trying to help.

  8. I wired the electric fan backwards on one of my cars. It would stay cool at idle. It would stay cool at high speed. But anywhere in between, the backwards blowing fan would cancel out the air coming through the grill, and it would overheat.

    Took me MONTHS to figure it out. I replaced the entire cooling system. I was so desperate that I even pulled the heads and opened up the coolant holes in the head gaskets. All because the fan plug had crumbled and I stuck the wires in…. backwards.

    1. For idling i guess it depends on the engine configuration, happened to me on a Citroën C3 with 1.2 turbo, engine compartment is tight and turbo and cat just behind the fan. At idling it overheated to the point of boiling and throwing out the coolant.

    2. Back in the ’80’s, guy I worked for bought his kid his first car.
      Fox body Mustang. Needed cooling system work so the father/son project began.
      After they were done, the car did the same thing you described.
      They couldn’t figure it out so I poke my head under the hood. We’re all standing in front of the car, staring down at the motor, doing that rev rev thing we always do while pondering what might be screwed up.
      That’s when I felt the wind blowing on my pants.
      While they were freshening up the cooling system they had replaced the stock fan with a generic flex fan. They had bought a standard V belt driven fan.
      Problem was, serpentine belt driven fans turn the opposite direction.

    3. I had a 1973 Mini – the kind with the radiator on the passenger side (of a right hand drive car) that had louvers in the wheel well that allowed air to pass through the rad and out through the well. The fan was a pusher fan – until I installed it backwards and created a hot-running Mini. It took some time before I discovered that I had screwed up.

    4. I see why you’re angry, Bob. That sounds exactly like the kind of sh*t I would do. Self sabotage. Once I somehow reversed the A/C lines going to the compressor. At least that mistake made itself known, and I mean right quick!

  9. Oof.
    My sympathies, I’ve been there. What’s worse mine was 100% my fault so hopefully you don’t have to run that gauntlet.

    Do you have another engine to install if worst comes to worst?

    1. I’ve seen it twice myself, both times on a Toyota 22RE (both 80s 4Runners), the ones that NEVER BREAK AND ARE BULLETPROOF AND INDESTRUCTIBLE and they’re just like any other engine. Any engine prone to self-destruction at the slightest overheating, and any engine with nightmare timing chain issues.

      Both times it was a cracked block that was discovered after the head was replaced. Both times the engine had 150k or less. Both times there was a quick engine swap and it was sold asap, which is what should have happened the first time.

      I bought a first gen CRX for a few hundred bucks that someone had spent big money redoing the top end, only to have the bottom end fail almost immediately. It was so clean and low mileage, I should have done an engine swap and kept it, but some kid trippled my money on it, so off it went (yes, he was WELL aware that it needed an engine).

  10. I thought you collected good running 4.0Ls. Why wasn’t this an engine swap and done? I know you might say hindsight is 20/20, but I thought it from the very beginning, and especially when you were having the head shaved and everything.

      1. Oh, I suppose it’s against the Wrencher’s Code to do something as logical as swap the shit engine out with a good one.

        It’s that Wrencher’s Code that has taken away this large chunk of your youth and will continue to do so as long as you faithfully pursue it.

        That said, I thought I had fun in my 20’s but in reality I was a complete asshole. So you’ve spent your 20’s hunched over rustbuckets. Nobody’s hurt which is more than I can say.

      2. I hope you’re right, but you’d have been done and probably could have come out cheaper at this point, not even considering your labor.

        Besides, my thinking was you’d rebuild the engine later, and have it ready to go into the next one?

        Good luck with it, I feel your pain.

  11. I was wishing for a better outcome of the weekend than this. It’s defeating when a something you enjoy turns into an obligation, and other people are depending on the repair getting done. I hope it’s something simple.

    I got to a point in my life where I had dependable cars, but missed wrenching. So what better way to always have something to wrench on than to buy an MGB? But it’s never been an obligation to work on it, and it can sit and wait if it needs something.

    1. Absolutely agree. I’ve had a couple British roadsters, but I’ve always had a reliable daily. I call it The Enabler Car (TM).

      It Enables me to get to work.
      It Enables me to have a fun car that needs TLC.
      It Enables me to give that TLC when I want to, not when I have to.

  12. Did you check the temp with an IR thermometer at the thermostat housing and compare to the gauge’s reading? Simple way to check cluster gauge’s accuracy before mounting a new gauge. Also, some vehicles are sensitive to the orientation of the thermostat’s small vent/pass-through hole (it should be facing up).

  13. Dude, that sucks, though I have faith you’ll get to the bottom of it. This far in, I wouldn’t give up now.

    This is just speculation, and doesn’t help address what is going on now, but with the history on this one, any chance that during the shenanigans trying to buy it, one of the salvage yards/repair shops pulled the original motor and threw in another junked engine?

  14. Nothing a gallon of gas and a match, or an LS swap, wouldn’t fix. I need to put together a list of everything I have replaced on the ol shitbox in the last year of ownership, I think I can give your list a run for its money! Mine still runs poorly, but seems to be decently reliable and at least doesn’t overheat so I have that going for me!

  15. Ugh I hate repairs gone wrong. I had a ‘67 El Camino that would overheat constantly.. after rebuilding the cooling system and building a proper shroud on the radiator it still had the same issue. We sold it not long after that, I miss how silly it was as a vehicle but by god did I hate messing with it.

  16. I saw one comment about reverse rotation water pump. I had a 1990 XJ with serpentine belt and am sure it was a reverse rotation pump. I think there is a casting mark on the pump housing iirc. I know it wouldn’t explain the rising oil level but might be worth double checking.

  17. It’s easy to have old cars, but hard to have old cars that run; there’s always another issue coming including with stuff you thought you already fixed. This is not the right vehicle for that lady who doesn’t have sense enough to shut down an overheating motor or have any money anyway, she needs a 15-year-old Camry or something.

  18. David, I just noticed something. You said that Tracy left with the title in her hand, but was going to send you the money when she got home. Did she ever pay you? I may have misunderstood, but, if no money has changed hands, tell her it cant be fixed, have her send back the title, and cancel the sale. Life is too short to keep banging your head against a brick wall.

  19. As it is gaining ‘oil’ the coolant is either leaking at the head gasket or the block- I had this happen when a head stud was too long and went through the water jacket- if I remember correctly it was some AMC thing AMX or a Cherokee- or a VW Iltis, as it just started I would suspect that moving the head around messed up the gasket

  20. David, you know what the Blackstone labs result will tell you, right? The thing rising in the dipstick is no oil, but blood – blood from the condemned leaking up from the pits of Hell into the jagged chambers of this cursed engine.
    Have a look at the coolant level and tell me if it isn’t also rising… whatever was is in there before is now being diluted in the tears of the sinners from below.
    Check the car history, I believe it will show that a previous owner decided to eschew a regular garage and just interred it in a pet cemetery, with a monkey’s paw in the glovebox just for good measure.
    Time to call a priest of your preferred belief system. They won’t fix the issue, but they may contain the demonic influence from spreading to the rest of your fleet. Trust me, you do not want to face a possessed Jeep FC :-S

  21. Sometime with an older engine that had the head off and then new gasket on the old block, would use a bottle of K-Seal or Blue Devil sealer to make sure things are good.
    Wouldn’t use Antifreeze till I was sure things were working right.

    Water in the oil won’t destroy bearings like Antifreeze will, when the motor is milkshake making mode.

    Once the system holds pressure with Water, then drain and replace with Antifreeze.

  22. Three weekends ago, my 2003 Outback overheated on the highway going to my parents’ house. No bubbles in the coolant reservoir, no milkshake oil, just a car that would rapidly overheat when standing still and then usually (but not always!) rapidly cool off when I got moving again.

    Two weekends ago, I burned up a whole weekend and a couple hundred bucks replacing the water pump, thermostat, timing belt, and performing a coolant flush. It did not go smoothly—I had multiple water pump bolts strip out their holes the aluminum cylinder block, I got a timing belt with subtly wrong reference marks on it, etc. But I got it all done, and my fiancee even drove it to and from her farm for a week with zero issues. I also ran a compression test on the engine, and got 180 +/- 2 psi on all cylinders. Great, right? Dodged a bullet!

    Last weekend, I drove it down to MA to return my parents’ 4Runner which they had very generously loaned me. Then, on the way back, it overheated again. Exact same symptoms… except this time there *are* bubbles in the coolant reservoir. God damn car had been hiding a blown head gasket the whole time. I mean, I know it’s an old Subie but I’d had the head gaskets replaced with the better-than-factory MLS ones less than 50,000 miles ago. I thought I was good on that, you know?

    Now I have a car with a blown head gasket that is too old and worthless to be worth investing the time and money into fixing. Replacing the head gaskets on a Subaru is an engine-out procedure, and while I’m generally looking to level up my wrenching skills, this just doesn’t seem worth it. I admitted defeat, put a bottle of head gasket sealer in there (I promise not to sell it to anyone without making it clear that it has blown gaskets) and commenced looking for a new ride.

    I’d really hoped to ride out this insane market with that Outback for a couple more years. Now though, my only trustworthy car is a 1996 Miata (glad I went with reliability when I bought a toy car) and I don’t drive that in the winter because salt. I need a new all-rounder, and I need it by October.

    I’m currently thinking either a hybrid Maverick or an AWD Mazda 3 hatch. Pretty different, but both viable options and both at similar price points. The Maverick gets better gas mileage, has more shit-hauling capability, and offers a platform for DIY improvement. The 3 is more luxurious, has AWD, is still practical enough for my needs, and is just… unf. Gorgeous. So pretty. Lickable.

    Anyway, that’s where I’m at. It’s been a ride, and I think I’ve made the right call admitting defeat in this case. Advice is welcome.

  23. First of all, hang in there, brother. We’ve all been there. In 1980 I bought an old house in East Tawas and, one Sunday night with the water off, I just could not get my solder joint to take. It was “make the joint, turn the water back on, find a leak, turn the water off and do it all again.” I was down to my last little bit of solder and, of course, there was no place to buy solder on a Sunday night in northeast Michigan. I cried. I swore. I prayed. But,eventually, I got it done. There was a reason my joints were bad, I just didn’t know why. (I finally became adept at sweating copper pipe). There is a reason your Jeep is overheating. You just know know that reason yet. You’ll get there, I’m sure.

  24. Came back to add that we are eager to learn the results of the oil analysis. My suggestion is, until you have those results, get a Coney Island and a Faygo to be good to yourself. If the oil analysis shows contamination, you can quit chasing gauges, sensing units, etc.

  25. Farty’s rules for interacting with David Tracy:
    1. DO – Read every article he writes. They may inspire you, make you laugh, make you question his (and sometimes your) sanity, and are generally entertaining and informative.
    2. DO NOT – Ever buy a car from him, no matter how reliable he says it is or excited he is about owning it.
    3. DO NOT – Rent him any home if you are not ok with the property around said home being a parking lot / mud bog.
    4. DO NOT – Take his advice about about what a reliable vehicle is (see rule #2). He does not understand what that word means.

  26. “Then I maneuvered the absurdly heavy cylinder head onto the engine. I’ll admit that I didn’t get it aligned perfectly, and had to slide both the head on top of the gasket as well as the gasket on top of the deck. But the surfaces were smooth, and everything slid easily until I could get all my head bolts tightened up.”

    Please don’t ever do this. If the block/head combo you’re working with doesn’t feature alignment dowels, then go to the hardware store and buy four long bolts with the same thread pitch as the head bolts. Cut the heads off, notch the ends so a flathead screwdriver fits and then screw them into the block to act as guides when positioning the head.

    Another practice I recommend is to retorque the head bolts after letting them set overnight. Following the pattern in the service manual, crack each one loose and torque it back to the exact same spec. If you mark the heads with a paint pen beforehand, you’ll notice that the bolt head position actually advances a little even though the same torque is being applied.

  27. It is funny reading through the list of stuff that you have done to that Jeep as I have done all of that and more on my ’94 F150 which, in contrast, I consider a great truck and never want to part with. I have been tempted over the years to get a different truck, but I stick with “the devil I know”. Every part I replace is one less thing I have to worry about, and I have done a lot of this work preemptively. It also helps that it is not my daily, and I do not have a customer waiting for it. It is all about perspective, I guess. I winced when you mentioned having to possibly redo the head gasket. My inline 6 Ford has a big iron head not unlike what you are dealing with, and it was a BEAR. Good luck getting it finally sorted. David Tracy will not be conquered by any car!

  28. A couple years ago my 1985 Jeep CJ had a vibration/rattle under the hood that would change with engine speed. I looked for any loose part. I even put strips of rubber under the headlight trim rings in hopes it was something simple. The rattle persisted. I was sure it was the water pump, so I replaced that. Nothing changed. Then I was sure it was the power steering pump which was the original pump. I lined up a replacement. Then, for some reason, I thought maybe the rattle wasn’t coming from under the hood. I slid under the Jeep and smacked on the exhaust system hoping to hear the familiar rattle. I got to the catalytic converter, smacked it, and bang, there was the rattle. After a decade, one of the ceramic inserts had gotten out of position and was literally rattling around inside the metal shell. I pulled it out, put in a straight pipe, and problem solved.

    1. ALRIGHT…. lets be sensible here:
      We are talking about a Jeep XJ.
      We are talking about a very sensible man… who has gone a bit crazy… and now he thinks… like the rest of us who get so fixated in a spot that we cant figure out which way is up.

      I SPENT 4hrs.. staring at my drill bit after I just drilled out a Disc Screw.. worrying if I had permentantly fucked up my whatchitwhoosit. Logic and Sense had both taken a vacation, I was left with OH FUCK and or Im going to Hell. Neither of which… mind you is going to get my wheels back on and my car going again.

      In short… because I am very OCD, ADHD, ADD… among a dozen other things….

      What kind of Pickle?
      Dill, flavored.. relish, 1/8″ sliced, 1/4″ sliced, are we talking pickle chips, pickle slices…

  29. Have you considered the radiator? I recently read an article authored by an eminent and respected former cooling system engineer. He was of the opinion that the radiator is of an inadequate size for the 4.0. If it’s clogged up with scale that will further impair its effectiveness. A $20 IR heat gun will let you read the difference in temp across the core, or you can just run your hand over it. You might try a flush or go big and have it rodded out by a rad shop.
    That doesn’t explain the increase in oil level, which is concerning. I know everybody here is pussyfooting around the words “cracked block”, but that possibility can’t be dismissed. I think it’s unlikely that sliding the head around a bit to align it would have damaged the gasket.
    Another long shot could a reverse water pump impeller. I’m not sure if the pumps interchange between the v-belt version and serp belt version of this pump without doing a parts lookup. I have seen this on both Ford and Chevy motors, but not sure if this is a reverse rotation pump or if they ever built a 4.0 with one. In twelve years owning a parts store, I saw a lot of stuff in the wrong box with the wrong part # on it that came right from the warehouse.
    At any rate, I’m sure you’ll figure this out without my help. I just posted this to say that I’m enjoying the hell out of the new site. The lineup here is full of big hitters, and you all have hit a grand slam home run. The addition of Mercedes makes it nearly complete. Now if you could just get Fancy Kristen to come over from the dark side….

  30. Okay, David, stop. Seriously.

    It passed combustion gas test. Your only symptom is overheat and gaining oil. So at this point you’re going about this problem completely and utterly wrong.

    One, you didn’t prime the oil system before starting it. It should be fine, but now you have to stop, check the oil, prime it using the distributor gear method, confirm 40PSI at the gauge. Let it sit 10 minutes, check again. If oil level does not INCREASE from your initial read and does not DECREASE below safe fill, you just had drainback from insufficient priming.
    Two, you have not done any electrical diagnosis after resolving the mechanical. You’re chasing zebras in a horse pasture. Don’t hook up a thermocouple or any of those shenanigans, test the CTS resistance first. These things fail regularly even without overheating. A failed CTS will either read zero OR will read high, giving a false impression of overheating.

    Do THOSE two steps before anything else.

    1. I just chucked in a new sensor for $8. It’s still overheating. I knew this, of course, as the temperature would stay centered under revs; there’s no reason a bad sensor would work when there’s lots of coolant flow/airflow and fail at idle. It was clearly working.

      As for priming the oil pump: I’m not really sure I understand why I’d do that? Do you prime your oil pump between oil changes?

      1. Which sensor? Again: there’s two. CTS, and ITS. ITS is the one in the head which sends to the IPS; CTS only controls the fan.

        You didn’t do an oil change. You had the cylinder head off for multiple days. That is an entirely different matter, especially on a high mileage engine, doubly so a 4.0. It’s a very simple procedure. You need a mechanical oil pressure gauge (you know how to hook that up,) a power drill, and a ‘special tool’ that slots into the distributor drive gear. The special tool is: literally anything you can use to turn the distributor drive gear at high RPM with slippage. Busted distributor bits and strong tape, GM SBC priming rod with some minor tweaks, whichever.
        That puts you directly on driving the oil pump. Go slow at first, then take it up to 40PSI as measured by the gauge, hold it for a while (want to cycle ALL the oil through the ENTIRE engine,) and that’s it. Oil is reprimed. The most important part is running it long enough to get all of the pushrods – which you completely drained – filled and bled. Dry pushrods make things unhappy and no, you won’t necessarily have scary noises with it.

        Any time oil level goes up significantly with no milkshake evidence, assume drainback or draindown and NOT gasket failure first. Always.

        Going back to the overheating, frankly, I am still not convinced that it’s actually overheating at this point. Is the fan operating correctly or at all? What ohm readings do you get from the CTS and ITS at dead-cold and at ‘overheating’? Do these values match? (They must.) Is there any actual evidence of coolant loss OR coolant boiling? Is coolant flowing into the recovery bottle?
        Again: your head gasket checks out, and your bores check out, based on the lack of combustion gases. There’s no reason to second guess your work here. Cylinder compression was consistent. As long as it’s within 10 across all cylinders, it’s worn rings and probably low oil during the test or a bad compression tester. If you did the head wrong, the compression would not come back like that. You’d have big variances.
        If all of those check out, go to the ITS connector and check the harness side. Ohm between pins (or pin and ground,) and if two pin, continuity from each pin to CLEAN metal on the cylinder head. Jiggle the harness a bit while doing this. It’s possible there’s a short in the IPC harness or the IPC itself has failed. These things do happen.

        Now that said, you called out an apparent pressure loss in the coolant system. You can’t pressure test these 4.0’s the same as other engines or even other 4.0’s on the early ones. They WILL lose pressure because it’s an open coolant recovery bottle and it always leaks. Always. A blocked passage would indicate no leak or possibly even increasing pressure.
        The important question in any suspected coolant leak is always: “are you losing coolant” and “is there evidence of contamination”? If you have no evidence to say yes to either of these questions, then you absolutely should not be proceeding as though you have a leak. The evidence clearly says you don’t.
        Which means you have a fan issue, airlock, or air pockets. Start by confirming the clutch fan operates. Then that the aux fan operates – that’s operated off the A/C high pressure sensor, which yes, also loves to go bad. If those both check out, that means pull the ITS sensor (yes really,) jack up the front end so the tires are about 2-4 inches off the ground or park on an incline, and start adding coolant till it’s puking out of the ITS sensor hole. Not dribbling. Puking. (Yes this procedure sucks.) Then try again.

        Based on all your symptoms, I just could not justify so much as pulling the valve cover unless oil pressure is excessively high or low. There is no indication whatsoever that you did anything incorrect there, there’s no indication the head gasket is leaking, there’s no indication of oil and coolant mixing, and no indication that you have a fracture in the block. So it has to be something with the monitoring or heat transfer itself, and likely something simple.

        1. I’m at the point where I’m coming to this site to read rootwyrm.

          Seriously, I don’t work on cars much of late, but I do program computer games all day, which means endless troubleshooting. And sometimes (too often) that means inadvertently “chasing zebras in a horse pasture” as our resident Jeep Motor Expert so eloquently put it. The difference between a good software engineer and an average one is that the good one only chases down the first hunch or two on a bug before getting systematic (attaching profilers, setting breakpoints, logging data, etc.). I’ve heard a similar aphorism about mechanics…

          1. Well thank you!

            Amusingly, I only do cars on the side these days, and more infrequently than I like (no space and frankly, have you fucking seen the housing market lately? I just gave up.)
            But by trade? Systems engineer, these days mostly in the DevOops space. How the fuck can an entire industry forget the prior 30 years? Sigh. And people wonder how I’ve worn out the Picard Facepalm emoji. The number of things which I justifiably consider ‘old hat’ and ‘basic knowledge’ which I have to teach supposed ‘experts’ on regularly is just… utterly fucking soul crushing.
            Between all the cancerous chain-dependency-hell ‘toolchains,’ the refusal by an entire generation to accept that what they are doing is not new and novel, the outright rejection of prior experience and dismissal of experts, overcomplicating shit for the sake of overcomplicating it, and the headlong race to the bottom?
            I honestly don’t know how I haven’t switched careers to alcoholism with a side-gig in day drinking.

        2. I second this emotion. I’m certainly no cooling system engineer, but it sure seems like a heat transfer or flow issue. Even a maxed out system like a 4.0 XJ should be able to stay relatively cool just driving down the road on a sixty degree day without a cooling fan if the radiator has decent flow.

          I can only imagine how frustrated and/or defeated he must feel at this point. Kicking himself about not changing the water pump. Blaming Tracy while knowing she didn’t know any better. Spending countless hours while lamenting the sunk cost. And all this while we’re looking over his should offering often foolish suggestions he’s already considered (I’m guilty). I wouldn’t be the least bit surprised if he wanted to tell us all to go fuck off. Obviously he’ll get past this, but it will leave him changed.

    2. I will also throw in that on the earlier 4.0 HO the temp gauge that goes to the dash is separate from the one on the front that goes to the ECU. Check that the sensor in the back DS corner of the head is hooked up and reading properly.

      1. Good catch, I always forget that obnoxious setup on these. And it’s so, so deeply obnoxious.

        Thermostat has a coolant temperature sensor (k-type thermocouple,) measure resistance across the two pins and bing bang boom you’re good or not.
        IPC uses a temperature sender, which depending on what was on the line that day, is a 1 or 2 line unit that ALSO loves to fail. One wire, measure resistance to ground path, then check engine ground strap. Two wire, measure across the pins.

  31. One of these days DT is just going to wake up and notice that he has a giant “4RUNNER” tramp stamp on his back side. He’ll wonder what really happened the night before, and without a good memory of it, he’ll just take that as an omen bestowed upon him by the ancient Roman God Wrenchius. We all know what happens next.

  32. Ive been here…
    I was tired
    I hadnt slept in 4 days
    I was seeing brake discs and calipers in my head
    My car was up on a self imposed lift — my wife was pissed at me cause she couldnt park her CAH in the right spot…
    It took me 4 days to undo a SCREW… and I felt utterly worthless.
    I spent 1 day calling around.. to have someone help me undo a damn Caliper bolt.

    I now know.. I was at the end of my rope.. when it was starting to rain, I didnt care. I was worried Id never get my car going again and these stupid screws are making me crazy.

    I couldnt undo the calipers.. they were fucked 3 ways to sunday.
    Pads were shit
    Discs were more warped than a big woman’s tittays.

    I went to school… to pick up my Son, looking like I just fell off a Flatbed. I walked up to the most sensible stranger I knew.. and asked if they had a 20lb sledge. I told them of my problem. Dude knocked it out in 5min.— I felt like human waste.

    Over the next week.. I put everything back together.
    But… personally, between you and I… I would seek professional help. PREFERABLY FREE. PREFERABLY with a SLEDGE and BEER. Why….. cause ya going to ruin yourself.

  33. David I know this isn’t very manly advice, but coming from a guy who has always been small and weak and is now old, small, and weaker, consider one of those $200 engine cranes from Harbor Freight to use for lowering your cylinder heads onto the block. (Chevy 6 guy speaking).

  34. May I suggest a section called “symptoms” laid out somewhere with all the summary details we need to see in a bullet list to look over? Maybe put it in a nice decorative box labelled “symptoms”.

    And, can we start an numbering system so we can keep track as time goes on. It would kinda be funny if you kept track of all the repairs done by the staff, with numbers. Mercedes is catching up fast, I’m sure.

    What was the first repair???

    1. For the next time, you can cut the top off of two spare head bolts if you have them and use a grinder to slightly taper the tops. Then screw them in a couple threads and use them as a guide to allow a more vertical placement. Sounds like you might have scratched up the water jacket sealant on the head gasket. Might be worth a quick change if you have a spare one.

      1. The independent mechanic that did my head gasket back in college had sets of all-thread he used to guide gaskets and heads on. Can’t slide that way.

        It was one of the most genius but entirely simple solutions I’ve encountered.

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