The Ultimate Guide To Identifying Jeep 4.0 Heads And Spotting Common Problems!

[@cwcadventures9987]

Let Justin talk. I wouldn’t mind if the video was 1 hour long. It would just keep me from having to dig through all your videos to find one I haven’t watched 😂

[@destinyballard925]

Yes! I love the longer videos, been watching Dex and Justin every day!

[@jaaxxone]

Best Jeep channel on the internet! Thanks!

[@dexjs]

Glad you think so!

[@tissuebocs]

I plan to try and rebuild my 4.0 in the next month or so, so im trying to absorb as much info as possible! Thank you for all your helpful videos!

[@killroy3607]

I rebuilt mine not long ago, their really easy!! Just take your time and you'll be good

[@taduse]

Thank you, thank you, thank you! I asked you to do video about this and here we are. 👍🏼😎

[@dexjs]

Hope you like it!

[@jakeclauson9863]

My 05 4.0 had 300k+ on original head. Matter of fact the only thing I did replace on that engine was 1 alternator, maybe 5 water pumps and 3 radiators. It'd been over heated more times than I'd like to admit. One time it got so hot it was only running on a couple cylinders by time I got off the highway and the thing still ran like a top. Another time the rad tank ruptured and exploded coolant all over the car ahead of me in the drive thru 😂 It was a good jeep. Barely had any issues with it besides rebuilding the front end a couple times and the usual frame rail rot. Considering I put 300k miles on it from new I think that's pretty good

[@ronaldbruzan9646]

This is a life time of info. Thanks for taking the time to video all of this Keep with long, short and mid length videos they are all good! Also your not a HACK you make things work big difference. WELL DONE.

[@hunterswiski8398]

Can you go through the ls valves and springs on your stroker head? I’m very interested that’s really cool I have a whole bunch of gen 3 valves and want to do that on a jeep engine

[@SGTRandyB]

I’m here for it. We’re talking about core engine stuff in 101 before engine class 103 next. 102 is electronics and happens after 103 for me.

[@TheMainLead]

Now I really want to see you daily a cracked head. Great video

[@dexjs]

Maybe one day!!

[@TheKernables]

I put 10,000 miles on my 01 with a crack at the base of the rocker. Ran great with no real issues besides loosing 1qt of coolant every couple of months. Replaced everything before I found it using dye in the coolant. Tried to JB weld it and that was a complete fail😂

[@shozdott]

i like Justin , he should teach more often imo :) good chewin da cud guys ty . your cool to Dex lol

[@johnweber4169]

2001 Jeep XJ with the factory 0331 head. Hopefully when I go to replace the valve cover gasket I don't see a fault line between 3 and 4. This video has helped me. I could listen to you and your brother all day.

[@Wiz-kidddd]

Might need a head right now so thanks for the help ,

[@melmontano5279]

Man you guys are bad ass. I enjoy the videos n all the info. I've rebuilt and mix matched a bunch of 4.0s blocks and heads. I learned the hard way to find out what works and what don't. Wish I had the videos when I was starting off. I'm sure alot of people find this helpful thanks guys

[@Neilman1000]

Typically most people would have two or three engines to look at side by side. So when they see a common issue with two or three engines. They will make a generalized statement that all of a similar type engine will have that same issue or will not have an issue. Making a statement based on a small sample my not be true. Dex, you and Justin have literally hundreds of engines to sample and from that you "can" make a generalized statement. Also the year comparison of heads was very interesting. Do more comparison and parts interchangeable vids. Thanks.

[@TsusStuff]

I'm so grateful that you guys do what you guys do. You guys speak well and present well. I get tons of value out of your content.

[@dannyski9123]

Ever run into different length push rods? Put a tuppy head on a 98 block after fighting low compression and finding bent valves for no apparent reason, put a tuppy on and got better but when rockers were tight valves were open, loose they had better compression

[@danfawcett9456]

Good stuff, Keep the videos coming guys!.

[@dissociativecat7495]

I have a 91,92, 94 xj and from my experience on valve seals when buying seals the 94 doesn't list as a fit on the 91,92. all three are 7120 heads. although I think they would fit just fine I went with what was the recommended fit. I personally like the positive lock type. and one other thing I found interesting is cam lift , rocker arm ratio is 1.5 not 1.6 on the older heads. look up melling camshaft specs. and see for yourself

[@beckybird5367]

Very interesting guys.

[@colin5064]

Excellent video with real world experience, what could be better than first hand knowledge on this topic. Cheers guys for sharing your time and experience.

[@hotoshideout2648]

You guys have the inventory of used heads to choose from, what about the average jeep owner? Do you suggest they go to the scrap yard and try to pull heads, or purchase an aftermarket head and try not to overheat it?

[@Markus_4.0ooh]

Imma check tomorrow, butI just think i cracked my head today 😅 hopefully its just the gasket but i hear a hissing in the back of the 4.0. Thank you in advance

[@Dragnssmoke]

i have had a 93 GC FOR 10 YEARS AND IT HAS 169,000 MILES ON IT AND IT RUNS GREAT

[@artardFTW]

renix motors also have a different cam profile - partly why they have less power

[@EmyBrowndogMom]

I did not know that. Thanks!

[@artardFTW]

@@EmyBrowndogMom renix transmission also has a slightly longer overdrive gear - changed in 91 - about a 300 rpm difference at 60mph

[@EmyBrowndogMom]

@@artardFTW Good info! I'm looking at a 2000 XJ right now. Nice to know they made those improvements.

[@chrismarsh9978]

Sooooo , you have a LOT of what you consider Junk Heads ,so can tje Cracked seats be fixed reasonably "ie" machine the seats out and replace them ??? Then weld the other cracks up just thinkin out load , we have welded rare tractor heads before !!! I'm just thinkin Heads are gonna start gettin harder to find , if yer just throwing them in the Iron pile for scrap, it might be worth a shot just to see if it's possible to save a few ??? Might not be economically feasible ???

[@janetbrowder6685]

I would think Dex and Justin would weld up and machine down a head for someone to try for durability, but doubt they would do any to sell. Agree with your scenario, someday they might have to repair cracked heads. **Good question. 👍👍

[@benmudn]

I once did work on a Chevy 250 I6 and after looking everywhere we could not find a non-cracked head, so the machine shop pinned it.

[@drew7767]

great video guys! thanks

[@Pigtrapper]

I dont have a jeep...anymore. first vehicle was a clean 83 cj7. Wish i never sold it. Anyways... i just pulled the head off my 22r. (Low compression on #4)... and about to pull a head on a free new holland 4630 that got so hot i had to pull the pan to get the oil out. Im sure its cracked... its gotta be. Only a 3cyl but im sure its cracked. Ill find out in a few weeks when i pull it. Love the videos man!!!!!

[@prevost8686]

Erosion of the coolant passage on the head that borders the fire ring of the head gasket will cause repeated issues on 22R engines. If that’s the case May as well buy one of the better quality new aftermarket heads.

[@Pigtrapper]

@prevost8686 supposedly when I bought the 22r truck... it had new head and new timing chain and tensioner. The rings are wore out on all cylenders. There's a lot of play in the pistons. The first 3 was checking at 100psi and #4 was around 45... if my gauge is right. I will definelty look it over good and check what you are saying. Makes sense since the back piston generally heats up more than the others. At least it does on a 5.9 cummins. I appreciate the tip!!!!

[@prevost8686]

@@Pigtrapper make sure you fill the intake and exhaust ports with liquid. I’ve seen quite a few of the cheapest heads that come with valves already installed leak at the valve seats. I was a Toyota master technician for 20 years and something really strange to hear of rings shot that bad. It’s easy enough to verify. When you pull the pistons out install the top compression ring back in the cylinder and feeler gauge the end gap. That’ll tell you how badly they are worn. They came factory with anywhere between 14-20 thousandths gap. If I can help you with anything let me know.

[@Pigtrapper]

@prevost8686 it's an 82 model that had a really hard life before I got her. I daily drove it for several years. Only putting about 20k miles in that time. Lots of blow by that kept getting worse. Finally wouldn't start.. and started kinda sounding like backfiring but I'm assuming it was just all the blow by when that #4 was combusting. Cylinder walls didn't have any scratches... just worn down a little where the rings rode.

[@billgeorge1142]

Thank you for answering the head issue's. Please talk about blocks next please

[@jeffbonifield8981]

Great session...Thanks! I was wondering if a product like Moroso ceramic seal would work for a coolant-into-oil leak if caught early? It has always been a band-aid fix for old drag race engines.Of course the ceramic seal must be applied as the directions indicate to be effective. i have a few of these old Jeeps so thanks for all that you put out there!

[@brianharris20]

I did not hear you mention it, but when they went from Renix to the HO head they also moved the intake port higher up on the head to allow for better flow. If you look at the two heads at about 2:36 of the video you can see the Renix intake bottom edge is about even with the exhaust and the HO is higher up on the head.

[@dexjs]

That does make sense 👍

[@robertrobertson3927]

You have put my mind at ease. Thank you guys.

[@jason200792able]

The wj engines with the two exhaust manifolds are those manifolds prone to cracking also? I have a loud ticking noise on the driver's side and while listening with a stethoscope the ticking is coming from the exhaust.

[@olduhfguy]

You have accumulated a lot of knowledge the 'hard way' but you don''t forget as fast that way. I have 7 WJ's - one has a 4.7 which is a big PIA to R&R, any secrets you'd like to pass along ? Keeping my TUPY's and using 0331's only when necessary. I have an XJ but I have to remember the incompatibity issues. Hope you can stay on the money makers and sell the extra parts you gather as you go. Nice to have a machine shop nearby 🙂

[@robertbryant7771]

I’m deep steeped in SBC but new to the 4.0. I heard that in 96 rhe 0630 with the new valve cover and gasket won’t interchange with the 7120 or Renix gasket and cover. Same with the 0331 that followed it. True or not?

[@nelsonflagg7667]

So that 45 digit number that's by cylinder 3 I believe there's a KZbin video it tells you certain numbers are more prominent to crack than other numbers.

[@revolutionday1]

Well, I have a 2002 WJ with the 4.0, that I bought from some folks that definitely overheated it, then it did it again on me once, as the fan control relay has gone-out twice. Between a shop and myself, the motor ended-up getting new pistons (shattered #4 and cracks in 3 of the others)/rings, rod bearings, head, intake/exhaust manifold, valve cover & oil pan gaskets, rocker arms/pivots & valve springs, with pushrods and a new fully-welded aluminum radiator. The shop swore the head wasn't warped or cracked, but after watching this video, well............... 😐

[@Jus931]

So for 4.0s, what is considered to hot? Anything over 210 ?

[@Skiridr22]

You guys have me freakin out now 😂 should take my head off to check for cracks

[@rafaeltorres2886]

Dex I need the fuse box located in the passenger compartment on the driver side because mine are corroded and the fuses pop out when I'm driving sometimes my blinkers don't work can you sell me one. I have 87 xj Renix . Would Edelbrock Aluminum head work on a Renix 4.0 ?

[@BlueEyedColonizer]

The burnt valves was interesting. Didn't know that. You can keep the video long as you can

[@Skiridr22]

I need to know more about those LS valves n springs

[@kurtarthur2311]

Can you put a 2005 tupy head on a 1993 4.0l block

[@kurtarthur2311]

With a 4x4 cam

[@alphajps]

Just started watching your videos and I'm wondering what the deal is with #5? I have a 99 Limited with 250000 miles that I bought for parts because of a bad knock. i can't bring myself to part it because its in such good shape. Anyways I checked it out without pulling the engine apart and its #5. I'm pretty sure its a skirt. Do you think there is a reason why #5 seems to bust skirts more often than the other cylinders or is this even a thing. I don't usually comment but I like your channel and appreciate your expertise.

[@dexjs]

We was talking about that today actually. I’ll try to explain one day.

[@droppeople7412]

just got my first zj for a trail rig it been sittin bc of a tcase but runs so good and smooth any tips to keep it cool i should know ? i wanna avoid getting it hot at all means

[@killroy3607]

Good, clean, coolant, and oil change every 3k! Oil helps keep the engine cool as well!! And a good fan clutch!! I promise that!

[@andrewchristiansen8311]

This is why I firmly believe the 98 XJ is the best year XJ. 99-01 had the smaller ported head. 97 had air bag issues, 96 below doesnt have air bags. I put in every factory option "Limited/Classic" can have in my 98 so I dont see a reason to get one without a good BCM or engine head. Why I'm saving my rusted 98.

[@andrewchristiansen8311]

Tupy headquarters is where I used to work in Farmington Hills.

[@BUKWulfSh0t]

Hey, so I'm looking into resurfacing my 97 shortblock or upgrading to a 98 better?

[@thunderzap2]

95 and 96 both have a driver airbag

[@johnbull6909]

I bought a new remanufactured 2.5 engine for my 86 jeep. Only got about 1,000. miles on it before it blew head gasket. The old engine had 310,000 miles on it. I got a new gasket and was torquing it down, got up to around 95 ft pounds and the bolt snapped off. Went to my old engine to grab a bolt and found that the bolts were fatter and did not fit. I think the remanufactured engine is from 1984. the problem is that the fat bolts 1/2" are easy to find, but the skinny ones 7/16" are next to impossible to find. I'm still looking to find some. Would you happen to know where to find these bolts? How much torque can they hold? Did this company send me a junk engine?

[@randomritchie]

Any opinions on the Edelbrock aluminum heads?

[@TexasRedneck]

15:00 the re...what? Oh you had an X at the end...ok lol

[@Denver1976Man]

Quick question. I have a bunch of 304 parts. The rockerts and hardware look the same. Have you or any one evewr used them on a 258?

[@joshuaervin7109]

Hey Dex do you have a trail ready jeep for sell? Let me know I’m not very far from ya and I’m looking for a new toy for me and my family.

[@randydaugherty1014]

Do u guys sale used parts looking for a head for a 96 jeep xj

[@dexjs]

We do. My job yes

[@randydaugherty1014]

Ok I pm u on Facebook what is a good way to get ahold of u guys need some parts for a 96

[@tomsmith2361]

Fascinating information 👍

[@jorgezuni2818]

Can I use a manifold intake From; 2000 jeep Cherroke4.0L to a 2004 Jeep wrangler 4.0L .? Do they port match ?

[@devonsaliers]

Would the 7120 head fit on a 2000 4.0 that came with the 0331?

[@jorgezuni2818]

Cracked head are they able to be Repaired like Welded ?

[@trippthomas3987]

Dex …… I took a motor out of a 1995 zj to go in my 1999 xj due to my xj having a hole in the block … tore the 95 zj motor down come to find out has bad head so I’m taking the xj head(99) to interchange it on the zj(95) block what gasket kit do I need to order for it to work 95 or 99 thanks in advance

[@danieljohnson8437]

Heat,..kills Electronics also. Thanks

[@MyBbgun123]

I have a question I hydro locked my 94 4.0 xj a week ago and now one of the lifters doesn’t sound like it’s building up a lot of pressure I didn’t bend a rod or a valve. Think I need to rebuild ? Or is there something I can do? I’m getting 40-45 psi of oil pressure when idling

[@yendortgone]

Great video. Do you have knowledge or an opinion on the aftermarket aluminum 4.0 head available?

[@dexjs]

Maybe one day. It’s very pricy

[@Denver1976Man]

Not worth 1800 friggin dollars. And I have yet to see any proof of 50 more HP. I researched them for a very short 5 minutes...lol

[@Juandongduck]

I always thought the high output was primarily the fuel system.

[@dexjs]

More fuel needs more air

[@Juandongduck]

@justdexit Very true sir. I guess I just assumed the head flowed well enough for the fuel system to be upgraded.

[@51-FS]

0:54 is that the rc jeep?

[@dexjs]

Haha yeahhhh. It parks wherever

[@AA-zm4ow]

​@@dexjswere are y'all located , do you have internet site ,, I am rebuilding 98 ,,,99 ,,04 4.0 wj grand Cherokee , I may need parts if y'all ship Dallas Texas

[@jonathanhodgdon650]

Dame I want to be this guy's friend

[@davidmccormack3114]

I have a 05 wrangler automatic, need a trans and wiring loom And computer! Help!

[@eastwest7194]

Can you put valve seats in a 4.0 inline head ?

[@420productions-j5o]

Great video

[@chinotaker1043]

So can I swap my 0630 head with a 7120 it’s work

[@scottChapman25]

Where are yall located for purchasing parts?

[@charlesmaxey9165]

Where can I get tupy head for 01 cherokee?

[@paulwatts905]

👍👍

[@ChickenNoodle0404]

can you weld the crack?

[@prevost8686]

The 4.0 was a very torquey engine but they sure had too many issues that should’ve been addressed.

[@waterloo123100]

To many issues 😂

[@comancheclub3449]

I always thought the 7120 was the best head.

[@tssxjfanatic]

NH is new haven

[@stephenhilton4665]

Someone already put chevy ls heads on a 4.0

[@Denver1976Man]

interesting.