Jeep 4.0L: Everything You Need to Know
Article: dustrunnersauto.com/jeep-amc-...
I tried to keep this unbiased, but I won't lie, I absolutely love these engines and i've had quite a bit of experience with them. The reason I love these motors is the same reason most people like them: they simply dont break.
Just in my personal experience i've had 4.0 liters run a 5 cylinders for extended periods of time, run way way below operating temperature from lack of thermostat, run on basically no oil, etc. I've even put a hole and dented an oil pan on a 4.0 liter bad enough that the crank started hitting the pan, and the motor still ran just fine after welded the hole shut.
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Berserker Offroad - • A Thank You To Jeep Ch...
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yeah mate the renix system aint all that garbage. you ever have to debug one of them fucks? ground them and the debug issues go away. You had such an epic breakdown but forgot that there is a cult following around renix due to how easy it is to troubleshoot. Fight me. I love you.
For performance from one check out David newcomer performance he has set the world record in hp for a 4.0
@@edgejerry1300 the name is Keith Newcomer I have his parts on my jeep stroker engine.
@@eranohad I'd love to modernize mine with a more modern engine managment system
For the renix computer @NickInTimeFilms has a computer monitor that he designed after reversed engineered.
When the last JL jeep is taken to the scrapyard, it will be towed there by a 4.0L jeep.
Confirmed 2020 Cherokee Latitude has no clearance and gets beat up instantly on even decent dirt roads.
The new cherokees are a joke they are a embarrassment to the name
@@rexmagi4606 Should just be called a Fiat Latitude.
By a chevy
Buy a Chevy what there blazer that is almost as bad and they build nothing that will go the distance and not rust away
'99 Cherokee with the 4.0 379,xxx miles and STILL runs like the day I bought it in 2000 with 11,000 miles on the clock. Most reliable vehicle I have ever owned. Might be why I've had it for 20 years. 😎👍
what engine oil do you use for it?
@@ethanm5639 no. Use Quartz 5000 for it. Or Shell Helix. Nothing else.
Me Too👍🏼🇺🇸
Mine has 233,000 miles and still runs and drives like new 99 Cherokee sport classic 4 door
315'000km, 01 Wrangler. just changed the original thermostat, water pump and timing chain. Cleaned the original radiator and threw it back in. That's all that has ever been changed on this engine judging by the old gaskets and stiffness of the bolts. Still runs like a clock, still hasn't cracked the original head or blew the gasket
My 4 Liter knocks and will continue knocking for years. It doesnt give a shit because it's a 4 liter
I ran one with a bad rod bearing for a year. To compensate, I used SAE 60w motor oil and used a light foot to accelerate. If you kept RPM below 2500, you'd never hear a sound out of it. Lol.
It’s a honey badger of an engine😂
@@randomcitizen2384 undeniably so! It was -11*F here yesterday morning, which has never happened since record keeping started here in the 1890s. The 4.0L in our WJ cranked slowly, but eventually fired right off, even with 230k miles on her. No block heater or Cosby in a Can.
@@shadetreejoe3986 That is cold!
@@randomcitizen2384 Much, much colder than I have ever seen. The good news is we got back up to 20*F, so I'm back in shorts and Crocs. LOL!
Probably the best american made engine in the past 30 years or more.
Maybe most durable but overall best probably has to go to an Ls or cummins (depending on what you prioritize in an engine)
@@fjcxucgkhcfoj3990 well there's many accounts of the 4.0 jeep motor running without out and going many more miles after putting oil back in it. Can u say the same about a cummins or ls. Actually I know of ls motors that have needed heads in less then 10 thousand miles. As far as I'm concerned ls is junk. I did mean as gasoline engines go through. However if I was going to mention diesel it would be the cat engine.
@@jasonglisson1690 4 liters crack cylinder heads too. The 5.3 had a small run of heads that had cracking issues. Stock vs stock the two are very equal in reliability terms. The LS has positively unreal power potential, something the 4.0 can't match. Also the softest LS gets better mileage while making 50% more power (5.3). These attributes make the LS an overall better design, along with being easier to package in almost every vehicle.
@@turbolq4 I've not seen a single ls have 300+ thousand miles and still running. I've seen many 4.0 that have. Actually u can build a 4.0 to 700 hp. At least that's the most I've seen so far. Also the heads cracking on 4.0s was very short. They fixed the problem the very next year. I guess we will just have to agree to disagree.
99-06 5.3 LS: Am i a joke you you?
Thanks for mentioning me (Frank Swygert). MY background on the AMC six is mostly on the car side, whereas you're obviously mostly on the Jeep side. Overall you did a great job! There are a few things I want to point out though. 1. The 232 six first appeared in 1964 in a special edition Rambler Classic two door hardtop coupe called the "Typhoon" -- after the engine name (that never really caught on, people just call it the Rambler or AMC... or Jeep... six). All were yellow with a black top and only 2520 were made. This was late in the model year (April release). The 232 was optional in other Classic models for 64 (for $59.95), but not too many were made. The 232 became available in the American for 1965, but not with air conditioning. The 232 is about 3.5" longer than the older 195.6. A special short shaft water pump (later used to put the 232 in CJ-5s) was used and the radiator moved about 2" forward. When the radiator was moved there was no longer room between the grille and radiator for an AC condensor. If you ordered the 232 and AC the AC option took precedence and you got the 195.6 anyway. A shorter stroke version of the 232, the 199, replaced the old 195.6 for 1966. The American was restyled with a slightly longer "nose" to create room for the standard length water pump and an AC condensor. 2. The 4.0L and 232 (and 199 and 258) are virtually the same block. The bell housing bolt pattern was changed in 1972 to be the same as the AMC V-8 (previously used the smaller 195.6 bell pattern), the deck height was increased in 1971 to create the 258 (which eliminated the 199), and the timing cover was changed in 1974 to accommodate different accessory mountings. To create the larger bore 4.0L (3.88" vs 3.75" for 199/232/258) the block was revised. It was made ~1/8" wider for the increased bore and the mechanical fuel pump mount was eliminated. Other changes were minor (like a couple extra casting holes... freeze plugs). Cams, cranks, heads, etc. will all interchange. The 4.0L uses a slightly wider and better design timing chain, which is sometimes used on the older engines. 3. Heads. There have been several 4.0L head versions which I won't get into. AMC/Jeep engineers really did all the work on the 4.0L, they just changed employers when Chrysler bought AMC. The work was done at the old Jeep facility by some of the engineers that were working there under AMC and developed the 4.0L. AMC changed the two center exhaust ports from a siamesed design (both center cylinders exiting into one wide port) to totally separate ports and raised the intake ports ~1/8" for a better intake charge entry angle in the RENIX head. The H.O. head intake ports were raised ~another 1/8" to further increase the intake charge radius. The early 2000 head, 0331 casting, did indeed crack more easily than others, at the location you indicated. You show a cracked head, but also inadvertently show a fixed head when showing the casting number. For some odd reason the casting number wasn't changed when the casting core was fixed. Instead the letters "TUPY" were cast across the head in the center. So if you have an 0331 casting you want to look for that TUPY -- which can usually be seen with a flashlight through the oil fill plug on the valve cover. 4. Another bit about the 4.0L head... It is a rather common upgrade for the 258, a bit less so on the 199/232. It's about 1.8" wider than the older heads, so the casting wash-out ports on the 4.0L head come very close to the edge of the 258 block (pre 87 258 -- I believe the 87-90 are the same width as the 4.0L). The head overhangs slightly on the right side (distributor side), but the ports don't. Being so close to the edge they may weep coolant once the engine gets up to temp and under pressure though. I've heard a couple people say coolant will "pour out". It might if core shift on a head casting was really bad, but I've done several head swaps and never saw one that bad. Those ports are just plugged (I've always used epoxy, some weld or drill round and use screw in plugs) to prevent this. Epoxy works well because the plugged area is fully supported by the block and head gasket. You must run a 4.0L exhaust manifold due to the center port change, and the valve cover design changed with the head, so you need a VC to match the head used. 5. Carbs on a 4.0L. For various reasons (cheap blow-thru turbo, racing class rules, etc.) some run carbs on 4.0L engines. Easy -- use a 258 intake by filing the bottoms of the "ears" with the hole to align the intake so that the ears sit on TOP of the alignment dowel and the top edge of the intake is even with the top edge of the head above the ports. Stick a 258 distributor in place of the 4.0L distributor (or later model cam position sensor). 6. RENIX vs. H.O. computers. You pretty much hit that one! I run a RENIX in my 63 Classic wagon. It's not that hard to diagnose, unless you're used to modern cars that at least give you a hint at what's wrong. It's more like a carbed engine, just slightly more complicated. Once you know what each of the 4-5 sensors do it's not too bad. There are a couple good diagnosis guides on-line. The H.O. computer was designed by Phillips. It's just an upgraded RENIX in most ways. The three big changes are that the EGR valve is eliminated (through minor cam and programming changes), the crankshaft position sensor was changed (Hall Effect switch in H.O., a magnetic coil in RENIX), and of course the ability to store codes. The RENIX does "store" codes, but the memory clears as soon as power is cut off. As you mentioned, there is no cheap way to read those codes either. At least the older Snap-On professional code reader would with the right module (expensive!) and the dealers had a reader (also expensive!). That's all that I know of, though some other pro readers of the era might. I probably missed something.. but those are the major points.
Thank you so much!
Class is in session, well stated! 👍
Thank you Mr. Wygert. Very thorough. Life time Amc admirer and current caretaker, restorer of a 2000 Jeep Cherokee. Decades of development make the 4.0 as special as it is. Great history lesson and video.
love my xj. Many thanks to you guys that made it happen!
Much respect. I appreciate the lesson from both y'all. Getting ready to do lifters on my 04 Jeep GC. Love learning all I can get my hands on in mechanics. Hats off to those who made it possibly 👏
The AMC 242 is the only engine that hits the million mile marker so often its never even talked about. The legacy this engine left behind is just one part of how brilliant AMC was. In all my years I have never found a brand that is even half the brand AMC was. Just goes to show that whats popular isnt necessarily whats good. Otherwise AMC would be thriving to this day.
Had a pacer and a hornet. Great 6 cylinder no issues.
Heard of such million mile vehicles/engines, outside USA, the Toyota LandCruiser 70 Series comes to mind, with the 1HZ Diesel 4.2 L I-6 engine.
AMC focused on iteration rather than innovation which helped reparability and reliability but when the gas crunch of the 70's hit that was ultimately their down fall. They should have really had stuck to Romneys guns of small, reliable, fuel efficient cars. instead they chased every trend like muscle cars, pony cars and luxury yachts (yes those cars classify as yachts).
Cough cough... Mercedes
@@AK-ITToyotas older engines are very long lived. But they make absolutely no power, and burn through more fuel than the 4.0 (Atleast the Toyota diesels do).
Had 5 Jeeps with the I6 4.0L engine. My last XJ had 200K and was running great. I just bought a 14 year old Jeep TJ with only 23K miles on it. Like getting a NEW Jeep. I tow this one behind our motorhome. Nope don't like the new minivan Jeeps. Will keep buying vintage until I cant drive anymore.
Hell yeah!!👍🏻 keep it old school.
Just curious what state you bought it in. The CA prices are ridiculous. I heard buy them in Tennessee. True?.
Well put ..I plan on doing the same
@@joannezorola4208 CA requires more assembly line work, than non-CA vehicles. Usually emissions stuff. So most cars are cheaper, when bought outside of CA. CA also has higher taxes than many places, so that also contributes...
I like my jeeps old enough to drink.
The 4.0 is as reliable as a hammer, if it blows up you’re either doing it wrong, or you’re surprised it’s lasted as long as it did. Not to mention the smooth torque curve and nice low end.
300k on mine make
My 97' 4.0 turns over and starts before you even hear the engine fully cycle on the starter. Key touches the contact and BAM. It bangs, it smells like gas, she wakes up rough but after all these years, shes ready to do business 24/7. Love these engines.
Check your o2 sensor
ive got a 97 as well..... and i think the "anti drain back" valve in the fuel pump has went if its been ~1 hour since the last start.... it will crank over 3 or 4 times . but if i cycle the key 3 times to prime the fuel rail (or its only been 10 mins since shutdown)...... it also spins about 1/4 turn and fires up . but it sounds like its running a bit rich...... check for exhaust leaks.......or an O2 sensor that isnt going from high to low voltage rapidly, especially bank 1 sensor 1 or you could have bad gas..... or spark plugs that are too hot in the heat range... or gapped wrong
@@kainhall yeah new exhaust going in this week. New engine mounts and a few other things. Love my ZJ.
@@kainhall but yeah buddy I had the exact same symptoms. New fuel pump.
I knew most of the information in your video, but I enjoy hearing someone else who shares my enthusiasm and love for the 4.0 I6 talk about these engines. Thank you for sharing!!
agreed i actually just got 450k miles yesterday and i’m the only owner scone 1998. The only engine maintenance i’ve done was lifters and head gasket. The rocker arms, water pump, etc are all factory.
@@cablenowadays6586 Wow…. that’s not very common to have one hold together that well for that amount of miles. Can’t believe the water pump has lasted that long, pretty amazing.
I once bought a TJ rubicon from a used car dealer. He was selling for $4500. It had 309k miles on it and was previously owned by the border patrol. I gave him 3800 for it and I put another 120k on it in the years I had it. I bought a new wrangler and a guy across town bought that rubicon from me. I still see it around once in a while.
My Jeep 4.0 has no issues. When I got it, it needed a radiator, thermostat, and water pump. Got those installed in an afternoon and almost 100k miles later, it's still going with no issues. It's not a fast engine, but it's quick for what it is. I've gotten it up to the top speed of 117 a few times and it didn't feel like it got heat soaked after that.
117 mph, wow! I got my '05 TJ Rocky Mtn with the 4.0 I6 up to 85 and that was only because I resumed the cruise control on the highway going up a hill. The rpm's went up and the growl from the Banks cat back exhaust was very throaty. The TJ is about the adventure, not for speed, but nice to know that the best engine ever put in any Jeep, the 4.0 has stout power to hit 80 with no issues.
Exactly what I just did. Actually, had to do the AC compressor + radiator + water pump. Now it's ready to go 200k+ miles. My '05 only has 77k right now.
My YJ has the 4.0 straight six and it is so easy to maintain, work on, and after 3 years of sitting, a fresh battery charge, she turned right over. Tough engines man.
Run some fuel cleaner through that for a couple of months if it's been sitting for that long. Might even need some new injectors. Gas turns to varnish after while.
My first engine ever! Super easy to work on and Damn near bullet proof. If you’ve got one, hold onto it and treat it well. It will take care of you if you take care of it!
250k miles on my 1998 Cherokee XJ with this engine. Just replaced the tires and took it on a long road and offroad trip through Colorado, Utah, and Arizona. Still chewing up roads like a boss. Zero engine trouble since I bought it in 2001.
My 98 Jeep Cherokee is the most reliable vehicle I have ever owned, desert toy now.......I love her. Lol
I have 99 and its very reliable in off road.
90 and best gamble ever made
My 98 XJ lasted 331K before it threw a rod and put a hole in the side So i put a rebuilt one in it and am looking to put another 330K on it Its been the most reliable vehicle I've ever owned. It took a lot of abuse and kept going.
@@abstract1dea Why U didn't Change it with used clean one?? Im not fun with rebuild engine.
@@user-wv5ec3tw4p could not find a low milage one and after a month of searching, decided on a rebuild Jasper engine. So far, its been excellent. But I've only put 6K on it. Besides, I'm doing some upgrades. Every part that breaks or wears out is an opportunity for an upgrade Thing about the old jeeps, there are so many choices for upgrades.
The 4.0 Jeep and the 4.9 Ford inline six can take a lot of punishment!
Yes the 300 in my opinion and a lot of others is that the 4.9 or 300 Ford is unkillable
@@mjhprojects321 Yep. Two of the most durable, reliable engines ever built. I've seen examples of both run well over 300K without the engine ever being opened up for any rebuild or repair. I have a '98 40.L with nearly 120K on it and it runs like brand new. I figure that it will easily hit the 300K mark and will outlive me.
Dont forget the slant six
@@spacecat7247 never die
What no toyota 2f love?
My mom owns a 2004 jeep grand cherokee with a 4.0l straight 6 and it has 200,000 miles on it and it runs like a champ !!!! 😁😁😁😁❤❤❤❤
I tow a lot with my Cherokee. One of the aggravating problems with the 4.0 here on the Gulf Coast in Summertime is that the fuel rail sits directly above the exhaust manifold. On hot days pulling my 16' covered trailer, it will stumble on startup after refueling and other short stops. The fuel in the rail tends to vaporize. Not a serious problem but sometimes it will throw a "Cylinder misfire" code which I have to erase. I put a heavier duty electric fan on it earlier, but the final cure was a temp probe in the radiator fins that turns the fan on at 160 F and off at 120 F. Wired directly to the battery (with proper relays and fuses) it will run a few minutes after shutdown on the hot days and blow air directly along the fuel rail. No start up stumbling anymore. The only problem is trying to explain to people why "Your fan is still running". Only a few minutes and it shuts off, so no battery issues.
I will back you 100% on this one. Purchased a neglected MJ 4.0/AW4 with 190,000 miles on it. Drove down with a buddy almost 200 miles to pick it up. Not only was it way down on power when we got there but it only had 3rd and 4th gear unless you manually down shifted it to 1st and 2nd meaning it would start out in 3rd gear in drive. I was pretty disappointed but the guy came down to $850 and it had brand new tires. Drove it back all the way home painfully slow. Got it home and no compression at on on the front cylinder. Turns out bent exhaust valve. Resurfaced the head and found broken wires above the transmission. $500 later for having a machine shop clean up the head, new fluids, and of course a water pump and it ran great. I used it as a daily driver for a long time and sold it for $2500 years later…… looking back I still miss that truck.
I beat the absolute hell out of my 4.0L jeep for 280K before I sold it. Never plugged in once in Canadian minus 40 winters. Spent more time at redline then idle. Never burned a drop of oil. One of the best motors ever. Wish they would have made a slight redesign for little more power and mpg.
Wish they would have too but the plan had always been to keep it like it was in order to keep from having to retool the factory. They made slight (almost meaningless) improvements over the years to keep the EPA off their backs until standards became so stringent that they just replaced it with that 3.7 V6. It never had an EGR valve or a Mass Airflow Sensor, or even a PCV valve. By the time they finally decided to phase the motor out it was a dinosaur. But one hell of a motor.
@@MrKnoxguy101 the patent for pushrod engine designs may be as old as the dinosaurs, but there's a reason why they're still popular enough for companies to make MODERN engines with pushrod technology
I'm in the UK, I've had several 4.0L's excellent engine apart from one massive issue. Fuel is over $7 a gallon here and a 4.0 has a serious drink problem
Agreed, but the money you save on it not going wrong really helps. No cambelts or engine issues. Just basic DIY servicing. Easy.
@@chriswarren2599 nope, gas is now over $10 a gallon in the UK. Also, cam belts don't generally cause issues
@@Bodgemiester 'Cambelts don't generally cause issues'. You're having a laugh. They snap causing engine damage. Even when changed at the correct service interval it can incur a bill at a garage of £500 or thereabouts. Get to some of the more complicated V6 and V8 engines it's getting on for £1000. The Jeep engine whilst thirsty around town, doesn't go wrong with basic maintenance that most home mechanics can do easily. Recently drove 1900 miles across Europe in my 4.0 Grand Cherokee ZJ. Averaging 65 mph with cruise gave me 27 mpg so for the reliability and comfort its well worth it.
@@chriswarren2599 no, cambelts are fine if maintained. Cam chains also snap trust me. I've also had 5 4.0L cheokees zj and xj and NEVER seen 27mpg. They are a very robust engine no doubt and I am a fan however I'm not putting them on athrone to be worshipped. The later ones crack heads and blow head gaskets, they piss oil everywhere and chew fuel like a power station. That said they are very simple and the correct year engines don't suffer major failure as a rule
@@Bodgemiester although you may not be wrong on your own personal experience, cam belts are a bitch and do tend to die out sometimes. Quit telling everyone there wrong your not a know it all lol. It happens to ppl. We can not qll be lucky as you haha !! Sadly , but for the up side our gas is not that high thankfully. And I have no engine problems ever. Just a u joint or yoke clamps here and there. I pray your gas price plummets
One thing you missed mentioning: These engines are really easy to work on in XJ Cherokees.
If you think the XJ is 'easy to work on' with this engine then a TJ would blow your mind in ease. Much larger engine bay (The XJ was never initially designed for the straight 6 - thus all the overheating issues). XJ's are probably the hardest of any vehicle they were put into to work on.
@@smackhead true, it gets cramped and there are some instances where you need to take off some parts to get to others- for ex you need to replace the rear main seal if you want to replace the oil pan gasket because you need to take it off with the way its built. its still stupid easy though compared to new cars. and idk if the overheating is all that common, even if it is the engine can probably handle it, thing can run without oil
That engine had the best sound. When my parents bought their first Grand Cherokee in 1993, they got the V8, but I preferred the in-line 6 when we test drove them due to its awesome sound.
The one and only bomb proof engine.
I'd rather have the 4.9 ford over the jeep 4.0
170, 198 or notably the 225 _SLANT6_ ? The same guy (Willem Weertmen) that helped design The Elephant 426 Hemi had a hand in this near forgotten bulletproof Mopar inline 6 motor.
@@blgarage9519 I second this there both bullet proof
@@slant6guy its a good block with a bad upper design. 1 carb leak and you are gonna be extinguishing a fire.
No, a 24 valve cumins is, not your wimpy ass jeep
They should bring that engine back in my opinion. Best engine ever made.
This engine is incredibly bulletproof. My friend bought a non-running one that had been sitting for a few months, we put a new starter motor in and it roared to life.
Try 6 six years of not never starting..... Charged the battery and fired up on first ignition........
@@MiguelGarcia-vj7oo tank of an engine.
9 years of mine sitting, flushed the fluids, new cooling system, new spark plugs, 370,000 KM and still runs like a beast
my 98 4.0L is all original with 325,000 miles. Doesn't sound super healthy, but it doesn't leak oil yet, and still full on power.
4.0L is the best engine feeling ever ... so reliable .. I have a BJ60 with a 3B and still ... love this 4.0liters
2f in a fj60 is gold too
@@anomilumiimulimona2924 it’s a ok engine but not put together as good as the amc straight sixes, it’s got 5 main bearings vs the amcs 7
@@mikolajrychlicki4866 yea, but the 2f reds at 4k so 5 mains isnt a prob
My 4.0 was pretty rock solid. (97 XJ) Thumb up for the history.
6:10 You showed a "tupy" head when mentioning the 0331 head prone to cracking. The "tupy" head is the improved head. 0331 without the "tupy" cast in between the cylinders should be avoided.
Good call on this one. The TUPY is the heavier 0331 head that has the thicker casting, nearly eliminating the cracking issue from the early 2000s.
You are correct but I have an 03 grand Cherokee and replaced the tupy 0331 head due to cracking in the same exact spot so who knows
Yes TUPY is Chrysler redesign version.
I had my first 4.0 XJ on 300k miles, was very happy with it and it did not have any issues at all for 60k+ miles during I had it. Got my 2nd XJ on 120k miles few years later, I seriously did not feel any performance drop neither on the engine nor on the transmission. For 100k miles it only wanted oil and water like the old one, and that's it. Never skipped a beat, never left me on the road, never embarassed me.. There was not a single day I thought "will my Jeep run or make this 1000k journey". It always did and I always knew it could.
I have seen these engines take on water, we pulled the plugs turned it over and it came right back to life. No issues at all, I have seen these engines held on rev limiter for minutes at a time.
Happened to me and it runs better than ever to this day 😂😂
There’s a video that was taken back in the “cash for clunkers” days where a 99-04 model Grand Cherokee with a 4.0 was drained of its oil completely, engine started with the accelerator braced to the floor. It ran wide open banging the rev limiter for over 15 minutes.. before it started smoking. It ran for another 6 minutes before the rpm’s began to slowly decrease. And as if someone had reached in and turned the ignition off.. it just quit, without as much as even an rattle.
Love the video. Thanks for doing it. I have a '98 TJ and a '98 XJ, both with the 4.0 I6. Each one is sitting just under 200k miles. I fix a lot of things on these vehicles and love how easy they are to work on and how easy it is to get parts. Both developed leaky pan gaskets. I've replaced the pan and RMS gaskets on the TJ. Gonna do the XJ this fall. I love these engines. Almost 25 years old, and they run really nice. Some day I might get one of those Golen mods, stroked out to 4.6L with 270 hp and 315 lb-ft torque.
You got it right bullet proof, I've been driving a 4.0 jeep cherokee for 8 months with a cracked head. No joke i put water in it every morning and I'm not scared to drive it hours away from home still!! MOPAR OR NO CAR!!!!
Thanks for reposting this video - searched for it a couple of days after I first viewed it several weeks ago and it was nowhere to be found...cheers!
One of my favourite engines of all time. Built like a tractor engine with 7 main bearings since 1964. Studebakers v8 is another of my favourites as well. I had a Comanche with the 4 litre and I should have kept it.
I had a single cab short box Comanche with a 4.0l, 5 speed, and Dana 44 rear diff. Damn I wish I had kept it. Lol
A man with taste and common sense. The Jeep 4.0 and the Studebaker V8's are as tough and reliable as any engine ever built, and with more character than a whole dealership full of LS motors.
@@kyleolin3566 I had one years ago, only mine was a long bed. I might still have it except the truck was totaled by an old man in a minivan. I replaced it with a year old 96 Cherokee with a 4.0, stick, 2 doors and not much else. Almost 25 years and over half a million miles later I still have that Jeep. Best car I've ever had.
Funny thing international harvester actually used the carbureted ones in their farm equipment
Had a buddy that had a Comanche.. cool little truck. An old man he bought it from had it since it was new and drove it very little and kept it in a garage for all those yrs. It was a cherry.
I hydrolocked my 4.0 and had it running In a matter of hours. It's still going strong to this day.
SAME!!
I hydrolocked mine and it slung a rod a couple months later. But I hit the shit out of the mud hole. Wide open. I knew I bent a rod or two. It was my dumb ass fault but it still ran for 2 months after that. And drove it up on the tow dolly with a hole in the block.
Best damn engine (in terms of reliability) ever made
Few years ago I bought a 2004 Jeep 4.0L for my Utah off road run around. The longer I have owned it the more impressed I am with performance. After reading your article and watching your video I understand why. Very impressed with your provided info and just would like to say thanks and keep up the good work.
One of the beauties of the AMC 242ci I6 engines is that a child could successfully work on them with some training. It is so logically laid out and so simple to do what would be considered a major repair in other engines that this engine should have never been terminated. The only thing I would change is that the exhaust and intake manifold are on the same side. Other than that, I love the engine tremendously. I have had four vehicles with the engine and still have two of them. I will never part with my 1997 Jeep Wrangler I bought new nor my 1998 Jeep Cherokee I have had for nearly sixteen years. Modern vehicles are made so stupidly, flimsy, ugly, and over engineered that I will likely never get any of them. I work on thsf garbage for a living. I do not want to take my work home with me. Few mechanics drive modern vehicles. We know the dark secrets these piles of junk and plastic have. The engine auto stop and start design flaw is going to get quite a few people very soon. People have no clue what happens when an engine is turned off, allowed to go to zero oil pressure and then restarted over and over. But they save a spoonful of fuel. The thousands in engine they will spend is inconsequential. People are so clueless.
So correct! I have gotten my engine hot where an aluminum block would just melt. I have done the Rubicon with no oil but yet it was synthetic coating that and got out of there that engine is Bulletproof amen.
I just got a jeep an yesterday with the 4.0 and I am so happy I love this motor
Had a 98 cherokee I ran hot every day for 3 months straight because of a bad radiator, ran it about 2-3 quarts low on oil several times because of a bad seal I eventually fixed along with the radiator. Damn thing still almost made it to 400k. They are definitely the toughest engine I've ever seen
i’ve got me a 98 grand cherokee laredo 4.0l it’s gonna be my first vehicle i hope it lives up to all this potential i hear about it!
We’re picking up a 99 4.0 today. Best damn engines known to man. Similar block to the other Clydesdale motor being the Ford model from 81… you will be fine. Change fluids and be sure you stay on top of your tune ups and you’ll be fine.
I have owned a 98 Cherokee with 309,000 plus miles & still runs great ,3 water pumps on my 4th radiator, my 1st rad. Was purchased from O 'Reily's & has a life time warranty ,so they keep giving me rads. I brought my wife a new 2018 Cherokee Limited ,which is a nice Jeep butI sti like & drive my 98 & will drive it forever.
On XJ number 6, this one has almost 300,000 miles on it.
I'm on xj 3. 5th 4.0
I’m having a cooling system problem just bought mine 6 months ago with a flat cam replaced the cam and now it like to get very hot. If you guys have any tips I would love to hear them!
@@myamaffei5778 flush the cooling system and check thermostat. If that doesn't help take the hood off to see if putting vents in it would help.
@@myamaffei5778 What year? Some of the 4.0 motors with aluminum heads like to heat soak and run hot. Later models (00-01) with the 0331 head casting are also prone to cracking, specifically between cylinder 3-4. My advice would be to get a better radiator than stock and some higher output electric fans with a lower temp thermostat. Especially if you live in a hot climate. I personally have an 01 with the shitty head and haven’t had any problems except for the heater core.
@@josholsen5736 For sure, I like to flush after every winter and replace the thermostat when I do. Things like to get stuck in there and cause the thermostat to not open which leads to overheating issues.
I had this motor in a 1995 xj Jeep. It was quite power full and performed well compared to my 4.1 ltr for inline 6 in the 1981 ZJ fairlane and 2000 AU falcon. I was impressed off road ability as in power. It was faster than most other 4x4s getting up to 0-100kms and sitting on 120km comfortably. However two major problems i found it liked to drink and get hot. I had the coolant water boil a few times but once cooled she kept going..
I had this engine in my Cherokee coupled to the Peugot 5 speed transmission. One day I was cruising at about 90 mph or a bit more. I looked down at my shifter and realized that I was still in fourth gear! No tachometer.
Brother, you did your research. Great video.
I got a 92. dont hit my head getting in and out. the wife died with a 2019 cadillac. I sold the cadillac and kept the jeep. inside armoralled with a cd player radio. I am good.
Have a 2004 Grand Cherokee, 452,000 miles, still running strong, all original, including the 42RH transmission
Awesome engines. I've got a '04 TJ Rubicon on 35" pitbull rockers, 4 low, 3rd gear is the sweet spot, gobs of bottom end torque, and usually enough speed in the gnarly trails. When its time for a rebuild might go with a Golen stroker kit.
I was an AMC Gremlin guy. That is what I always liked and the Hornet as well and I really liked the 258cid straight 6 and they were bulletproof. I am pissed that my 03 Grand Cherokee was 2000 miles away from hitting 500000 miles when a drunk driver reared me at 100mph. The 4.0 is the best straight 6 ever made. Great video and a props for the 4.0
That’s what happened to me too. Had a 99 four liter Grand Cherokee for 7 yrs when one day was about to turn into my driveway when a drunk driver in a little Jeep Liberty (of all things) rear ends me, knocking me into a neighbors yard. I hopped a ditch that caused one of my coil springs to come flying out and missed a utility pole by mere inches. The Liberty sped away whining loudly and spewing coolant all the way down the road. They found him… but that was the end of the Jeep. Bummer.
your points were right on Sir..............excellent. thx
While looking for a TJ I came across a 98 with almost 300k miles that had sat for nearly 10 years. The damn thing still fired up with a little starter fluid and a jump start. I ended up finding a 97 with the 4.0 and a 5 speed with 87k miles. The frame needed some attention but the tub looks great underneath. Ended up going with that one and with a little love to keep the salt away I plan to keep the thing forever
I had a 4 liter with almost 300k miles on it and it was still strong as ever with no issues at all when I sold it. Wish I still had that one.
I and my son have owned a number of Jeeps with this engine. It's a very torquey engine and with just a little work can be pretty powerful and last forever. I put a Borla header, Flowmaster muffler and high performance fuel injectors on my '93 ZJ 4.0 and was very impressed by the power.
I have a 93 YJ with a 4.0 Liter, how’d you increase the power?
@@quinnmullen1086 he literally just said how he increased power. Borla header, flowmasters muffler, and fuel injectors. They don't add a ton of power on their own, but it's not about the gains of each individual modification, it's about how much it all adds up to.
I used to have a Gremlin 77 with the 242 engine inline 6, indestructible twice I broke a rod and it kept going making clacking sounds, but running, it always ran really cold never failed sold it in 1994, ran with the guy I sold it and its still running, in good condition, (rust in the doors and hatch) but it is a damn tractor.
Really nice to hear and see all the info I had questions on in one video. Thanks
My 99 Xj has almost 400,000 Mile's and is just like New.... Original Head Gasket and 🐈.. A real beast on the street and trail.
I have an '05 TJ Rocky Mtn with the amazing bulletproof 4.0 I6, which as you mentioned does not have the thin 0331 header, thank God. With just over 153k miles, it runs absolutely amazing. I've been using Valvoline 10w30 150K+ synthetic blend oil and have noticed a tremendous difference in how it idles and performs overall since switching over from the Valvoline 10w30 75k+ mile oil. I also use marvel mystery oil and BG44K products for gas and oil treatment. MMO is good but doesn't compare to BG44K in quality and effectiveness. I can see this 4.0 lasting no less than 500k miles before needing an engine rebuild. I ignorantly had an '08 JK X with that pos 3.8 mini van engine. And these engines are on the opposite sides of the spectrum, from worst to the best. I will never have another Jeep after '06. If I ever get another, it will be either a CJ-7 Laredo or a CJ-8 Scrambler with the 4.2L. But I will never get rid of my '05 TJ Rocky Mtn! Great video! O|||||||O 🇺🇸 Only in a 2 Dr 🇺🇸 '41 - '06
I have a 1996 XJ with 446k miles original engine.
Thank you! Recently purchased a 97TJ with a 4.0. Subscribed from Canada
Got a 95 grand cherokee with the I6 and the thing is a beast. One time I drove 250miles with only a single bolt holding the head gasket together (bad mechanic screwed me) and after getting a new head gasket seal the thing ran perfectly. Told the story to a customer one time and the guy wanted to buy it on the spot lol. I only got 116k miles on her but I plan on keeping her till I'm old(26 atm).
My 1991 has 379,886 on her. She sat for two years before I finally went and got her again. All she needed was a battery and she fired right up. And before I even got her, my uncle had her for 8 years when he was in college. The only thing he did to her in 8 years was ONE oil change.... She's still purring to this day. Suspension is basically gone though lol. Tbf, everything except the headlights is from the dealer.
98 ZJ. Current daily driver. 300k Motor has hard froze a couple times, overheated badly a few times. It is indestructible and I love it. Very solid bone stock veh off road as well. Loves to climb.
My sister owned a Jeep TJ X with the 4.0L. She ran it for 4 months with less than a quart of oil. It's still running good with 175,000 miles on it. It's been off road and rev'd hard. I own it now and it's a fun little offroader.
My radiator blew up, bad. I was a few miles from home when it went, coolant all over the windshield, white smoke pouring out and the temp guage pretty much pinned in the red. Got it home, had the radiator replaced and checked over, still runs like a champ with 165,000 miles on it. Part of the reason I haven't gotten a newer jeep is the V6 they put in it, other part is I can't afford one....lol.. Gonna drive my '03 Rubicon until one of us dies. :) Ps. Nice video, just subbed.
Own a 95 4.0, bruh gotta swap it 😎 because I sent CL 6 to space 💪just passed Saturn
Years ago I had a 4 door Mercury Zephyr GS with a 3.3 LIter I6 , I sold it with 274,000 miles and it still ran very well.
Coming home from Taft, CA fully loaded with gear. I topped off just before getting on the 5. Did 90 up the Grapevine with the AC on came down the 5 through L.A. got home in La Mesa, CA only used a half a tank of gas. Love that '03 Grand Cherokee and it's still going strong.
The one other glitch you forgot was the noisy lifters. Lifter tick is super common with this engine. It doesn't do anything to reliability, it's just slightly annoying. I've had a few that have gone 300k miles with lifter ticking and never had any other problem with the motor.
Piston skirts on later models were known for being weak as well. Piston slap developed and # six cylinder’s piston was known on occasion for breaking it’s skirts but usually continued to operate. If the pieces of the piston skirt fell without getting bound up in the rotating assembly, they’d just settle in the oil pan. That old 4 liter had no quit in it.
MMO = Marvel Mystery Oil
Engineer and Race Engine Builder for 40 years. How do I trailer my Drag Bikes to the track ? Jeep Cherokee 4.0 with almost 300k miles. T.S. RACING 🇺🇸💪🏍
307k this month on mine.
This 3 year old video showed up 8/27/23! As an inline 6 fanatic, I own a '96 Grand Cherokee with a 4.0 plus a '95 F150 with a 4.9. my two favorite inline 6's for all the reasons you've stated. Thanks!
Had one I bought not running, never let me down, love the 4.0!
I agree one of the best engines ever built! I've seen them with over 250k miles still running like a top. Take care of your shit and it'll take care of you. With this engine even if you don't take care of them they'll still keep running. Can't say the same for the rest of the drive train but that engine is like you said basically bullet proof! Great video!!
Can’t forget the 300 Ford straight six
My favorite as well. I've had 2 ZJs and 2 WJs all with the 4.0. 2 which I put over 330k miles on them. Love that motor!
Actively looking for another WJ 4.0 preferably 2003 or 2004
I’ve gotten water in my ‘88 4.0 while mudding a handful of times, it’s been over revved many times, been overheated past the end of the temp gauge once or twice, and has run on 5 and even 4 cylinders multiple times, all at over 230,000 miles. The ONLY issue I’ve had with it over 5 years is the original water pump going out, absolutely bulletproof.
Wow, absolutely great break down. As the owner of a 4.0l 94 XJ and currently a 00 XJ I found this video not only informative, but also dead spot on accurate. Especially the parts about the 0331 head cracking (been there), the rear main seal leaks (basically almost always there), as well as them being bullet proof (once drove mine in traffic with a radiator leak and super overheated it with no damage). The only thing I can add is that along with being bullet proof, the cost of parts for them is ridiculously cheap and most mechanics find them extremely easy to work on. Lastly, the one negative thing about them that was left out is how bad the MPG is both city and highway.
The cool thing about the 4.0 and the rear main seal leaking is that it can be replaced in a just few hours by dropping the oil pan and the rear bearing cap. Other engines have rear main seals that require pulling the transmission or dissembling the engine to replace that seal.
Yep, I had the 2.5 engine, still got 19 mpg, but parts were cheap. had to replace a leaky exhaust that kept giving the O2 sensor bad readings. A new exhaust manifold was $60 lol.
Still on the original 0331 head on my 2000 XJ at 382,XXX miles, we bought it new and it has not been abused or overheated. My son got a '97 XJ a few years ago with the 4.0 (and AX-15 5-speed :) ) , had 29X,XXX miles when he got it, now over 305,000 and runs great as well. No idea how it was taken care of but seems rock solid. The 2000 is a 4.0 4x4 with the automatic, gets 13-14 mpg city, my sons '97 is two wheel drive stick. 16-17 mpg city.
My father had on that he kept on the road to like 300k miles, kept tubing the floor out cause it kept rusting, the engine was still healthy and running when he finally had to let it go, cause of the rust issue, I just recently bought a 01 cherokee with the 4.0 with 180k, she is a beast and I plan on keeping her as long as I possibly can, she's may daily. Most reliable engine ever made !!
My jeep cherokee 2001 has 347k miles on it. It has a misfire I have to figure out, but I've had it for 20 years and still going.
Excellent review - I had 2 versions and love them both - 90 Comanche and 98 TJ. Both with 5 speed. The Comanche was very quick for a truck. I would love to have either again!
I love my 01 JGC and runs like it is still new. I traded a ham radio for get mine because my black JGC was white with bird doo doo after it was parked under a tree for 3 years. I replaced the bald tires, replaced top hose, put new alt, replaced the Coil Pack, replaced the original plugs with 1/4 gap to new double platinum plugs, replaced front shocks and both frame bumpers during the last 4 years I’ve owned it. I replaced the valve cover gasket, adjusted the kickdown cable. I did remove the front passenger headlight to replace the radiator fan switch which is inside the front bumper by cutting a 5” panel on the top, then using duck tape to hold the panel in place, re-install headlight and overheat problem gone but boiled the coolant out of the reserve bottle 3 times before I figure it out. God, I love my Jeep.
I had both the 2.5 L and 4L. The 2.5 L had horrible horsepower. I had a 2000 Jeep TJ and I have replaced many components including the water pump. All these components were very easy to get access. Very reliable and only the very components needed to be replace. A lot more torq than the 2007 Jeep Wrangler
As an accomplished lifetime mechanic I've only seen one 4.0L jeep engine suffer a catastrophic failure. My buddies wife lost her tampon or something and took it out on his 95' cherokee and over-reved the piss out of it on purpose and it had spit the center of the cam out of the block.. He asked me to find out why it doesn't start anymore. So I popped the hood and seen a section of the camshaft sitting there next to the battery and said "well this might have something to do with your problem, besides from being married to a psychopath"..
Dang--both to the engine failure and your description of it.
Somebody needed some midol, and a hug...🙄
@@amjrpain919 LMAO
@@amjrpain919 ...I often hug my Jeep....
Not sure why the cam would fail nor how a broken cam could exit the block ... also its low in the engine ....this doesn't seem possible
I had an 87 XJ Cherokee with the 4.0... great motor
I LIVE IN THE GREAT STATE OF TENNESSEE A LOT OF JEEP OWNERS HERE!BEEN TURNING WRENCHES FOR 53 YEARS COMING UP ON 70,SO HERE ARE THE FACTS!THIS MOTOR HAS BEEN AROUND FOR 77 YEARS!FIRST USED IN THE NASH 600 BACK IN 1946,IT WAS CALLED "SUPER 242"!NASH AND HUDSON MERGED THEY BROUGHT KAISER JEEP,AMC BOUGHT THESE 3,THEN CHRYSLER BOUGHT AMC.THE CO.AMERICAN MOTOR CO.WAS WAY AHEAD OF ITS TIME,THEY HAD THE 1ST ALL WHEEL CROSSOVER ,,THE EAGLE THE DEVELOPED A/C,,ROTORS PADS,POWER WINDOWS AND LOCKS AND CRUISE,WHILE FORD AND CHEVY WERE TWILDING THIER THUMBS.ITS A SIMPLE ENGINE BUT A BEAST THATS WHY I OWN A 95 Z J 26 YEARS OLD NOT A DROP OF OIL ON THE DRIVEWAY CLOSE TO 410,000!
I have a '91 Cherokee Larado 4.0-HO that just turned 250K with the only issue being the rear main seal leaking. I'm with you; I love that engine! Any issue I have had was not engine-related. Loved your video and agree wholeheartedly.
Those rear main seals start leaking the minute they roll out of the factory, trust me you are not alone with that issue. I am on Jeep number five (Wrangler Rubicon 06 currently), all of them had the Straight 6 motor.
If it’s leaking that means it’s got oil
I appreciate these engines also the new jeeps are complete junk,they look cool but i hate them
Sadly in my opinion jeep died in 06ish with the last of the 4.0s
Jeep died in 06 with the tj. The real death was in 2001 with the death of the greatest jeep ever. The legendary XJ RIP. A moment of silence for our fallen heroes
Bc they are not jeeps, they are a Fiat garbage,that used Jeep name for sales purposes only😷
They don't even look that cool. The new Cherokee looks like a toy. If you can't tell your Jeep apart from a Hyundai, you don't have a Jeep.
@@felipevalles8041 JINO Jeep In Name Only
I had 4 of them over about 20 years. 300,000+ miles. Cjs, tjs and cherokees. Best engine ever.
Looking at buying a 2005 4.0 for my daughter. I thought this video was truly excellent. Well done! Thanks and I just subbed.
Will you do tips and tricks on the cooling system?
i found a manual wrangler 4.0 with minimalistic surface rust. I'm planning on having it at my summerplace and learing how to build on it and offroad and go to the dock where my boat is. i'm really tempted. i'm only fifteen though. still i really am considering it
I picked up an automatic cj7 (1985) with 4.2 liter i6. I definitely thinks you should get it. I’m 15 too and I don’t regret my choice at all. I love being able to learn to work on it, and getting a vehicle that will go anywhere. Mine came with a three inch lift and 33’s too though.
Nice summary/explanation of the 4.0. I have two 1996 XJ Sports. 429,000 all original now starting some piston slap when cold. The other XJ Sport with 302,000, it's a baby 👶 . Simple maintenance is all that is required with regular oil changes.
Ive recently just got a 2002 jeep WJ 4.0 and I love it so far still have to put in work had to replace the radiator and the alternator, replaced the air filter to t wix air filter but so I still have to chance the cv joint of the front drive shaft going to the transfer case, recently changed the oil to castrol gtx 10w-40 and add a quartz of lucas oil stop leak with a wix oil fitler , next also have to change the tranmission oil and replacement the transmission fitler as well and would like to get a flow master exhaust system by the summer
Yes the 4.0 is almost indestructible- back in the late 2000's when the government had their buyback program- dealers had to make sure the cars or engines would not be used again by breaking the engines most commonly by running them without oil. I know the Jeep dealers ended up having to pour sand in the 4.0's to get them to finally seize up. What a shame and sad.
that was straight up commie crap
282000 miles on my 4.0 I change the oil every 3000 miles no smokin and uses a quarter quart of oil in the 3000 miles. pennzoil 10w30.
I had a Toyota Machito in Venezuela. 5 cylinder in line. A monster amount of torque. Same engines were used in the Land Cruiser pick ups, Largos and Ballenas.
It really is as great as you feel. I'm 61 and have, experienced and am experiencing the Chrysler 225 and two Jeep TJ 4.0s. The common denominator being the smoothness and legendary reliability of both of them. Man, my 2005 TJ always fires up immediately. I've got 33s on it, along with an overall 4" lift, so it's not great for using all six gears. I'd love to regear it, but not with the Dana 35s it has. So, 44s that are already geared for 33s is the plan. With only 76k miles on it, I think I'll leave it mostly alone for another year. After a 70 mile run to the range in 90+ degree temps, it will drip maybe 2-3 drops of oil in 2-3 days, and then stop. Local trips don't faze it. Love the 4.0 and it, along with a manual, was a must have.