How To Rebuild a Jeep Engine part 1

The Jeep 4.0 liter six-cylinder engine provided exciting acceleration in Jeep Wranglers for years, with excellent torque. Based on the old 199 cubic inch Typhoon Six introduced in 1964 (via the tall-deck 232), the AMC-engineered engine used a shallow-skirt cast-iron block with evenly spaced cylinder bores, loop-flow combustion chambers, in-line valves, and a seven-main-bearing crankshaft. According to AMC historian Frank Swygert, the 4.0 block is around 1/8" wider, due to the 0.10" larger bore, and the lack of mechanical fuel pump support; 4.0 heads can be bolted to the earlier 232 and 258 I-6 blocks (the ports on the right edge have to be sealed when this is done, to avoid seeping coolant).
To create the 4.0, the older engines' bore and stroke were also changed, but engineers tried to preserve parts and dimensions to reduce the need for new tooling and inventory; all internal parts interchange, according to Swygert, among the late-1964 and newer sixes in the 232/258/4.0 family. He wrote that it's "relatively common to put a 258 crank and rods in a 4.0L to make a 280 inch six. This can be done with all stock parts (258 crank/rods, 4.0L block/pistons), but most often a special piston is used along with the slightly longer 4.0L rods.
When the 4.0 first came out, AMC was using two six cylinder engines, a troublesome 2.8 liter V6 from General Motors (with a similarly troublesome Ford carburetor) and AMC's 258 CID (4.2 liter) straight-six, which had been derived from the 232 cubic inch six. The 4.2 was used in the CJ7, Concord, Spirit, and Eagle, after having debuted as the sole Eagle engine and an optional Wrangler motor.
A related engine, the 2.5 liter four-cylinder, was based on the same basic architecture, and appeared in 1983; Frank Swygert wrote that it was essentially the 258 with the center two cylinders removed and a new head. The 2.5 was engineered by AMC to be "part of a two-engine set," according to Willem Weertman; the other engine would be the 4.0 liter six. The four-cylinder produced 125 horsepower in its final years, and replaced a 2.5 liter GM engine; to confuse matters, Chrysler made a 2.5 liter four as well, producing a meager 100 hp with throttle-body fuel injection.
The YJ gave way to the TJ for the 1997 model year (note that there was no 1996 model year; the 1997 TJ was released in Spring 1996). This updated Wrangler featured a coil-spring suspension (based on that of the Jeep Grand Cherokee) for better ride and handling, and a return to the classic CJ's round headlamps. The engine is the same 4.0 L AMC 242 Straight-6 used in the Cherokee and Grand Cherokee. A 2.5 L AMC 150 Inline-4 motor was available on entry-level models until 2003 when the 2.4 L DOHC 4-cylinder engine previously used on the Chrysler PT Cruiser replaced it.
A right hand drive version of the TJ was available for export markets, and was also offered for sale to US rural route postal carriers. The version offered to US postal carriers was only available with an automatic transmission.
A modified 98 TJ offroading in Alaska
In 1999, the fuel tank became standard at 19 U.S. gallons (72 L; 16 imp gal) capacity. There were some changes that occurred between the 2002 and 2003 years that made some parts difficult to directly swap back and forth, but also made it easy to identify certain years. From 1997 to 2002, the side door mirrors were black metal framed mirrors; and from 2003 to 2006 they were plastic molded mirrors. The fit of hard and soft tops is slightly different, and the fabric and colors available changed from 2002 to 2003. In 2003, the 3-speed automatic transmission was replaced with a 4-speed automatic with overdrive. It has the standard option of turning off overdrive with a dash switch if desired. The radio bezels went from a rectangle in 2002 to a rounded edged rectangle in 2003, so swapping these also required the console to either be swapped out or modified. The sound bar inside was changed to sound pods. The interior seats also changed design from 2002 to 2003, going from a rounder model to one with a distinct separation between back and headrest areas.
The standard skid plate was also revised for 2003 to make room for the Rubicon's bigger NV241OR transfer case. The change from the 30/32RH to the 42RLE also gained an additional skid plate.
This version of the Wrangler is also notable for being the last production vehicle to use AMC-related parts. The AMC Straight-4 engine was retired after the 2002 model year, and both the AMC Straight-6 engine and the door handles (the latter of which first appeared on AMC vehicles in the late 1960s) were retired along with this generation in 2006. Like the YJ Wrangler, the TJ Wrangler used both the AMC passenger car door handles as well as the larger door handles off the AMC-built Jeep CJ for higher-end models.

[@Y10Q]

this is by far one of the best engines designed. All inline 6 engines are great, but this one was made for easy maintenance.

[@macsogandares8383]

+Y10Q This and the ford 300, great engines. I wish they still put those in their trucks, other than what sells I'm not sure why they don't make them anymore.

[@omegarugal9283]

because they are too long... apparently... ditch a smooth and reliable design because oh is too large and we can`t fit it with all the extra crap we put in our cars these days... for a small car used simple inline 4s goddam it...

[@macsogandares8383]

Omega Rugal Can't agree more. It isn't easy to fit an inline-configuration engine into an engine bay, but a modern engine bay is also a lot of wasted space. Center of mass isn't a reason to stop making them either, you won't be street-racing a work truck.

[@LittleMikeStarCraft]

Agreed-- the 4.0L is the best.

[@sethmorton8539]

It last too long engines with low rpm life by design last longer like all inline kerosine engines less block twist holds true longer I had a 4.9 Ford and I have the Jeep 4.0 ho not much goes wrong if you change the oil and don’t over rev the engine last over 200.000 miles what I have noticed is the Maine bearings in these motors I would definitely upgrade those better than stock late 80s early 90s they skimp on a lot of things like pulling the zinc out of motor oil that’s what made all engines last longer when you rebuild these use oil with high zinc and detergent

[@351cleavland]

Little Timmy fell down in the well!!! I need part 2 so I can put this motor together and drive out and save him!!!!

[@derrinpickett9948]

Always number the main caps with a punch and make sure they go back in the same spot when you re-assemble.

[@bigtexjn]

Great video, very informative to me. I've never done any engine work before but this shed a good bit of light on the inner workings of a 4.0. Look forward to part 2

[@hook86]

Awesome video. I have always loved this engine and would kind of enjoy the chance to crack one open, but I'm afraid they are just so darn reliable I've never had occasion to!

[@darkfenix2001]

You have a great way of showing things quickly and explaining them effectively. I hope you give us part 2 someday!

[@jabesrosado7406]

I am a current student at a mechanic school I was very impressed on how easy you made this look good job hope to absorb more knowledge from ya

[@mudpro200]

Great work, hope you do part 2 for those of us that want to learn more about the build part of the 4.0 engine. Thanks!

[@sagiputerman]

WOW you have a ton of knowledge I AM impressed i'm sure you will not forget to replace the 5 galvanized water seal i think there's brass seal available,but you probably now wating for more LONG videos P.s i understand that Mrs Wranglerstar reads all the comments so hello to you too,from the last Israeli survivor

[@johnathanreigard512]

Great video and I can't even believe the amount of effort you put into the description! Thumps up! 👍👍

[@copperheadsevenpointthree8523]

...and Parts 2, etc? Are you able to re-upload them? I know most of this, but it's amazing how much one picks up seeing someone else do it, it helps much. Thanks Cody- You and yours are always in our prayers- Paul and family

[@xXBuckOFiveXx]

Ha what a coincidence, I just started to rebuild my 2.5l in my comanche. It's my first engine rebuild so im looking forward to this series. Thanks Cody.

[@tomalexander7313]

Man i follow your other channels Im getting ready to buy another 4.0 for my 93 ZJ and want to rebuild it. Love your videos

[@benniehoskins4745]

I've been a long time follower of your other channel and never knew you had this channel as well. So glad I found this one. As always, Great work!

[@misterpolytech]

Is this a joke?

[@dodgedakotastampede]

One of the best videos I watched good job like how u take time to explain the parts

[@survivaleveryday]

Thanks for making this video series

[@Firetech412]

Close on the thermostat. the spring adds tension to the valve, yes, but the valve is actually opened by the wax in the center of the spring. as the coolant heats up, the wax begins to soften, thus opening the thermostat.

[@DannerPlace]

Very interesting for me to see. I have a 2001 TJ 4.0 liter since new. One day, I'll have to go into the engine. So far, so good.

[@Mark622111]

Love it, video flows without a lot of how to do this or do that...most of us know how to turn a wrench. Well Done.

[@towtruckmafia]

Got one of those 4.0L's in my Comanche. 200,000 plus miles, I need to rebuild mine too.

[@iBR4NDON]

Awesome vid!!! Doing mine currently!

[@Dj_Caribe]

Straight to the point perfect vid

[@craigebers38]

I recognized your voice before I ever saw the channel name. Great job!

[@stevelenorastoops830]

Very well done! Thank you!

[@rockyoursht]

we're not all bad drivers, im 19 and have a 1999 jeep cherokee with 196000 miles on the first clutch, the biggest repair my jeeps needed so far was a new alternator. although i will admit a lot of kids are bad drivers

[@MrTintin850]

Very interesting, thank you Cody.

[@unclefreddie7562]

i need part 2! lol awesome video my friend!

[@genghisman39]

Thats a nice looking engine. I'm wanting to pull the I6 in my jeep for a rebuild

[@calebgrundyson8848]

This is very educational! Thanks!

[@carslover3509]

thanks great video

[@mdj2023]

That engine is clean!

[@81eagle]

That's what I was thinking. I would like to have seen the #4 piston a little closer, but yeah, it was pretty clean.

[@devinhansen7696]

Could you possibly post videos that show the rest of this rebuilt. I'm currently in the process of rebuilding an inline 6 from a 1993 jeep cherokee. I would greatly appreciate it

[@rileysnyder5154]

Hey Cody, did you have a part 2 (& more?) to this? I blew the 4.0 in my XJ last night, but I have a couple of donor vehicles...

[@macsogandares8383]

I believe it's called a girdle (what you were referring to as the crankshaft cradle). Still, interesting teardown. I didn't know they had those.

[@cristianalvarado880]

Hi there Why is it that the continuation of this excellent video does not appear ?, I think is the best of the web! You can upload again ??? Thank you

[@ginodacosta1739]

wheres part 2? this is a really great video!!

[@swampratman2000]

congrats on the new channel

[@darrinkorbie]

You make some great videos, thanks for hat you do.

[@nitrohead88]

That motor looked like it was in great shape .

[@th3frogman]

Are you gonna have more videos on Jeep installation and so on?

[@the88tlc]

this is not rebuilding, but only taking apart. that is the easy part. that hard is to understand what is out of tolerance, what needs to be replaced, and to put back together correctly, with proper bearings, parts, and the right torque for all major bearing bolts, and head bolts.

[@hellayoung8672]

This is part 1 u dumb shit can u not read😒

[@trappy77]

The thermostat works by expanding wax inside the spring works against the expanding wax to close the valve as the wax cools.

[@jessedielschneider8757]

great vid, i have an 03 GC with a 4.0 it leaks a little oil near the back of the engine. i have replaced the valve cover gasket and it still leaks any suggestions on where to look? also how long do these motors typically last? in my case it has had regular oil changes every 6k,it's 2wd so very little off-roading and i live in the country so almost all the miles are highway miles.

[@user-fs3ym8ik6e]

since what year have begun to apply the plate stiffness pillows on the root of the crankshaft? I have a jeep zj 1994 without her. what would you advise,to put???

[@Search4GodsElect]

I got a question for you. It's actually keeping me from finishing my engine so I can install it, At the end of the cam shaft and between the timing chain cover is supposed to be some sort of spring that keeps the cam from bumping into and damaging the timing belt cover. My engine builder said I needed one but they are impossible to find. What do you think? Leonard, Denver

[@kssnyder2]

It's probably pretty obvious by now why there's no part 2

[@supersonictoast2822]

+kssnyder2 cause he put it all back together and bent a pushrod and spun 3 bearings and blew the headgasket on the first start up haha all the shit he did wrong

[@MrWallyrooster]

Part 2 is actually dumping it off at the scrap yard

[@verume1]

yeah, timing chain is what I meant....I thought you had to make the marks is what I was getting at...but you say they are already there so that answers my question...thanks...mr. wranglstar never got back to me on that....or any other questions for that matter.,whatever...but thank you "gravediggerracing" for getting back to me on that....Your awsome bro...God bless

[@NefariousRake]

I have a few questions. if I'm not mistaken Cody, this engine is the same one in the zj's correct? as well as the xi's too?

[@neolexington]

Excellent video, I actually have two TJ's in my garage right now with that engine. Is there any difference between a '97 and a '04 4.0 engine?

[@OverlandGeneration]

lake dillon colorado? my favorite place in colorado is peru creek....

[@queerdeer12]

Trying to figure out how I went from Oil pressure sending unit on an f150 to the tear down of a I6

[@CatcherOfBass]

Increase my killing power eh? Let's do it! Thank you, I have learned a lot from this video.

[@lauradahlus]

Hey! I drive my Hot Pink CJ7 like a pro.. Actually I baby him. Probably not good either. :P

[@cascadematt]

This is great. For the mechanically impaired(trying to learn), is there something specific you're replacing in the engine? love the vids

[@queerdeer12]

how dare you not make a part 2!!!!

[@ianamacleod]

Awesome video! I have a 1995 wrangler, 4.0l with 200,000miles on her. Any ideas when a rebild might be in order?

[@basharatrajpoot9317]

I love this cars engineering's thank you am happy

[@marcusdavid3]

When are you going to make part two

[@buttchy78]

When taking a head off work from the middle out or run the risk of warping the head.

[@thelocustemperor]

Could you put an Packard or Buick straight eight in a jeep?

[@alexmolina7705]

Where you buy the engine rebuild kit? I see few but not sure what to buy

[@mark.audacity]

This is such a good video, where's Part 2??

[@hadenough7901]

+mark audacity romberg Yeah, that is always a bother. I don't understand series not being...in series

[@noahkormanis2009]

How did you keep all the pushrods in order?

[@user-fn6ls5hr4q]

no part 2?

[@tranhau3818]

This type of engines have been used for years. Are there any inventions for newer type of engines? I mean not 2 stroke or 4 stroke engines, but others.

[@MrPlogan247]

Hi Wranglerstar, Love your work! Just curious, are the wranglers considered "reliable" and which motor/drivetrain or models do you recommend? Kind regards from Australia! Keep up the great work mate! -Pat

[@bonza167]

my 2005 TJ with the AMC 4.0 six and six speed manual has been reliable in the 18 years I've owned and hundreds of thousands kilometres later here in Australia

[@szili76]

Part 2 is part 1 played backwards!

[@Taylorhpatrick]

Did you zero out the crank before removing the head?

[@suncountryairline]

One of the options in overhauling aircraft engines is to chrome the cylinders instead of using oversize pistions.

[@garciazapata]

Great video but where´s the second part?

[@_google_user_]

what is the green slime called

[@Graveltrucking]

What made that engine fail it looks clean, it has been run a little hot but it is clean even the out side the block is clean unless you steam cleaned it before started to work on it. It has seen regular oil changes to visable sludge in the valve cover.

[@stevenlusk8706]

Is there a part2?

[@haidarabdallah]

WranglerstarDIY, is there a part 2? If there is, could you please share it?

[@FARTNOISE100]

Albert get a coder reader that give definition match sells a small one for around $80 alot of the code don't trigger the check engine light sneaky Chrysler! alot of the work on jeeps is fairly easy it all depends on you if you have the time and the tools jeep forums are great!!

[@adam7637]

would it be worth putting a new bigger cam on my 93 jeep cherokee 4.0 with 190000+ miles?

[@zondapower3234]

engine coolant thermostats have wax in the small central cylinder and when it reaches a certain temperature point the wax changes state from a solid to a liquid, its that change of state which causing it to expand and thus pushes on the connecting rod which opens the valve, the large spring is used to close the valve when the wax returns to a solid, its nothing to do with thermal dynamics or thermal reaction of the large spring its sole purpose is to close the valve, just look at the design and which way the valve moves.

[@muddy78cj5]

Did you ever complete part 2?

[@albertort1]

I need help, i saw an 01 jeep cherokee with 109k miles, what should i be aware of, if i get it? Thanks for the help.

[@13tucker45]

Wait, this isn't the channel I thought it was... I was on realfixesrealfast... but now I'm here...

[@ed0985587]

Not sure I have seen a video that contained more information in a ~7 minute span. I assume there is no part 2 since so many people below are asking for it. Good job with part one though.

[@macsogandares8383]

NICE impact gun. That had to cost a lot.

[@Mrizing]

I had a question I need help, if anyone here or you can point me in the right direction or what do I need to buy next Heres whats going on, I have a 1991 jeep cherokee 4.0. 217,000 k miles on it, it was burning oil so I had no choice but open it up and see what is going inside. Took off the head saw bad burnt values so I started with the head took them all out cleanded them up and did value job with compound and that rubber tool to re seat them everything looked perfect after that seat was perfect also value steams where changed few months before this so they looked OK. After the head I saw the block walls where smooth with no cross patterns left, so I took all the pistons out rings where not stuck or brunt they moved freely, next I re hoaned the walls to make the crisscross pattern I removed all the rings and cleaned all pistons up everything was super clean and rings where moving like they where new I also replaced the piston bearings cause they showed sign of wear. Before I put everything back I did a simple test put one piston in and poured oil on top of it to see if oil would drop through the rings left it for 2 days no oil went through I did the same test before I did the hoan and clean up of piston rings and oil fell through within hours. So I thought this was a good sign. after hoaning and ring clean up I believed rings where tight and no blow by was going to happen. Then I put everything back in. the car stared perfect and I thought everything was great then I did compression test each read same reading 125.125.125.125.124 126. So I drove it about 100 miles and oil was below safe line, OKi though maybe the rings need time to set in new block walls but no 1000 miles later I'm burning even more oil then before almost a whole quart every 70 miles that's really really bad. My mistake I feel is because I didn't replace the piston rings ? But they looked totally fine and where moving with ease. Please what do you think I did wrong here? I don't want to give up on this jeep but this is crzy how much oil it's going through I'm willing to take it apart again trying to fix it, currently it has good power no blue smoke but the oil I just disappearing. Sorry this is so long but I'm so lost and any help would be greatly appreciated. Do I need to buy new piston rings? Maybe sleeves?

[@JfFoliguetbig-bear-lake]

Is Part 2 done? Thanks

[@VWfreakVR6]

I have a 90 wrangler with a burnt piston, how in depth do i have to get to replace the pistons? I already have a piston kit for the engine and warm weather is here and I would like to get working on it again. Can the pistons come out the top to avoid removing the crank? Thanks in advance for any help.

[@93paxon]

Thomas Cornell you may be able to rotate the crank from the bottom of the engine while you disconnect the pistons from the crank. then you can push them out of the top of the engine.

[@rogerwoody9493]

I have a 98 ZJ and I want to get some power out of it. Do you have any videos with some tips? I also have a 4.5" rough country lift. I do my work my self and appreciate your videos. I don't have money to pay anyone and probably would still do it my self if I did.

[@keyworksales6241]

Roger Woody I know this is late but I would definitely start with a cold air intake and better headers. that can free up 20hp with the right exhaust

[@Flyyakker13]

Part 2!!

[@DracoOmnia]

where is part 2!?!

[@byrdjp]

I'm already thinking of trying to drop one of these in my 2011 Unlimited. The new 3.8L V6 just really doesn't impress me at all.

[@LifeinTwinFalls]

Another vote for a Part 2, please.

[@monkeynemec]

hello is there a part 2 3 4 to this?

[@MrWallyrooster]

He gave up, couldn't figure it out. Part 2 is dumping it off at the scrap yard.

[@erichimes3062]

Dude is trying to be a jack of all trades...maybe engine rebuilding isn’t his strong suit, thus no part 2?

[@donjackson8816]

What is the milage on that engine? Someone really maintained fantastic. Don

[@verume1]

so you don't have to worry about marking the timing belt before taking it off. does it just go right back on any kinda way? ......."no, I'm not trying to be smart, serious question"...I am still learning about this sorta thing...G.B.

[@JohnnyBLC]

What happened to Part 2 ??

[@estebandavilaruiz22]

Super engine 6 cil , is a good manufactured amc and chrysler jeep

[@colby.wriborg]

how much does a 4.0 weight?? Just the motor

[@bassmaster4209]

I hope it is be coming a stoker motor there is not a 4.0 video of it

[@_google_user_]

part 2?

[@leftlanedrivers]

Why no part 2?