I Thought This Would Be A Simple Fix, But It Tested My 20 Years Of Experience To New Levels! 

You may think this is a wasted video but while chasing this i learned so much , one of my favorite tbh ty man

Dex, I enjoy your videos. You're honest mechanic looking to solve problems and not just take customers money. Folks like you are hard to find these days. Thank you for your work ethics.

I really appreciate your knowledge on these Jeeps. Plz keep posting videos.

I looked at this Jeep before it came to you(not on my channel though). Checked all the basic things I could and came up empty. Didn't realize it was gonna be this in depth. The owner has it at the shop that built the engine. They got the lifters squared away but something still isn't right. Maybe they will get it soon. Thanks for the in depth video!

Need to check the lifter pre-load. My theory is they decked the head/block excessively and now the pushrods are too long, especially on 1 and 6 where the most material is removed. Really easy to check with a dial gauge with the valve cover off. If confirmed, shim each rocker accordingly or order correct length pushrods.

Please I need a review on this truck it looks so nicely built simple but cool

Must have been frustrating working on that jeep but at least a great video came from it.

Thanks for showing everything Dex !!

Sorry you didn’t get to fix it Dex! Awesome diagnosis though. Thanks for recording it for us!

Hopefully the parts for that 5.0L Stroker will come in and you can make a video on it.😁👍👍💪

Always check vacuum if valve train is questionable Love your channel

I bought a rebuilt motor and found out the shop put in the wrong cam shaft thinking it would make more power. check the lift on the push rods to see where it is at. have a good day

Could we get an update when owner gets it figured out?

Props to you for being willing to eat it like that 👍👍. Good job 👍👍

That was an amazing video! So much high level xj knowledge, and you still took a whoopin!

You remind me of me when my Jeep yj coil died but still had a spark enough for me to assume it wasn’t that. It ended up killing my bearings from the fuel washed oil

I really want to know what it is. I’m having same issue with ford 3.0 driving me Krazy. New motor new everything. I did everything you did. Sitting on the edge of my seat waiting to hear what it was. Lol

Look here bud....this channel is awesome....just the kind of attitude content...everything someone really wants to see...good job man jeep up the good work....love that you are real...im gonna comment more often to help out your growth

Lifters and cam, bet ya. Valve timing is off so you have pre detonation.

id inspect the pushrods next. check length and for deformation. otherwise lifter/lifter bore and if not that, camshaft.

You deserve a good scanner

Your the Jeep whisperer 😅, you figured out more than anyone else, maybe it's a faulty cut cam with a bad lobe. I've seen 'em come from China before, they just happened to get one when they built the motor. I've seen bad injectors from China also. That's why I like the Mitsubishi engines in the later years, those Rendix engines usually don't run correctly do to vacuum leaks. It seems like a bad cam lobe not machined properly to me, in a way

was hoping to glean some clues on my cylinder 6 misfire. still informative-keep doing this stuff!

Just watched a video from @ProjectDanH and he had a similar problem and it turned out being the wire harness where it comes behind the engine near the top of the head. It had rubbed on the stud and caused some wires to fray and melt, causing a short in the fuel injector and made it run rough. just an idea for you. and pretty much the only thing they all have in common is the wiring harness.

Thanks for the videos and great job!

Thanks for the in depth video! Love seeing how much your channel is growing!! You definitely deserve it

Beautiful commanche

New motor with a cam lifter issue is super common

Always check the crimps on the grounds

You earned a subscriber on this one.

Do a running compresion test it could be a low spot in camshaft. put compresion guage on running moter or fast cranking. compare cylinders.

Good work weather it was fixed or not, who knows who put the engine together..

if the guage bounces it could be a lifter over pumping because of a low spot on the back side of the cam lobe.

Man these look like the problems I get while working on stuff.

My 5.2 zj acted the exact same way turned out to be a bad temp sensor that wasn't throwing a code

Please let us know what it was if it ends up solved.

I’ve not watched the whole video yet. But my Jeep 4.0 the tcm was shorting out I had to get a replacement for it no problem. Mine would flood and die. Hope you get it fixed with the flex plate

Good job

My YJ did something like that once after I got it stuck in mud. The heat from the header melted a vacuum line under the intake. It’s near the firewall. 🤷🏻‍♂️

So ..... a set of $600 adjustable rocker arms in that trucks future ?

More new engine installs go like this than people think, but most are small issues that people just ignore. My brother paid a ridiculous amount of money to have his Ranger's engine replaced, when all it needed was some top end love :\ not listening to me, he had a refurbished engine installed, and it's got a stuck/sticking lifter, self fix on warm up, but still, it will be an issue. Think he'll take it back, hell no, he's intimidated, and those fk's kept his truck for 3 months! A job that should have taken 3 days max, since the all parts were pre-ordered. It came back with non- working rpm gauge, power steering issues, and a random shut off problem, not to mention they lost half of his stock air box! He paid $2k for this stupidity >< bc he was too embarrassed that he was taken as a fool to say anything about it, kept making excuses for the shop, etc. Btw he could have bought another used Ranger for the price of new engine work. Those litle Ford 4 bangers are hard to kill, unless you let a crap mechanic get their paws on them.

It’s like that skit from Kids in the Hall, “I tried spitting at it, and cussing at it, it still won’t run”

Many people do not think about the push rod length when they are cutting the heads. Idk how much was taken off the heads but I would bet they need be 10-20 thou shorter esp on 1 and 6. Depends on the method they used to cut the head and if they was in a hurry!!

30 years tech . I get paid to find the problem and fix it !

i got a real doozie of a electrical issue on mine thats new, that ive never seen before, after installing a new transmission in.

So relateable. Do you have a scanner that can read the computer? My actron unit works on jeeps. Their computers are pretty advanced imo.

That timing chain looks like it's too loose to me

May be that TSB for renix distributors indexing etc...

Old dex sweatn a crank sensor but ripped the Trans out..😂.

I burned my 2door 5speed to the ground in my back yard because I couldn't figure it out and got mad at it.years later it hit me that I had the wrong flywheel on it..

Heycdex my 88 Comanche bounces off the low Rev limiter and I replaced all my sensors 😅 😢 no fix

Spray some carb cleaner around the intake manifold

My Jeep did the exact same thing. I am currently swapping the motor. The old one had 240000 on it. It is not a Renix. I was hoping you could figure out the problem so I would know what to do if it does the same thing again.

tough one dude

Buy it and swap a 4200 L6 out of chevy trailblazer in lt same style computer as ls 100hp than 4.0 easy to use 4l60e and 231 t case fits nicely under xj mj hood

If the fly wheel is off, I don’t think the car would even start.

I've been having horrible problems with fuel injectors! Running like a hole or 2 down? I fixed it finally but literally replaced everything b4 I figured it out!

You can absolutely charge for diagnostics!!!! Most shops do….

Put a scope on the crank sensor look at the wave form i bet its the senosor wiring

Had the same thing happen to a 99 4.0 insalled valve spring height?

fuel filter wrong direction lol or fuel regulator gasket leaking past return or inconsistent voltage with ballast resister / relay ....

Whos the owner i have questions on that comanche

Rough day at the office i see

Check the injection

This is one of those 2 day diags that you charge $150 for lol

So did you ever figure out what the issue was?

Let's hope they broke the cam in properly. If not that could be the reason it's losing compression and running poorly

I got a 89 Comanche with the 4.0 it idles really high sometimes and I have to cut it off and crank it a few times and it will idle right any idea where I need to start and it seems like it has no power

Hows it run with the 02 just unplugged?

OK IF YOU DON'T MAKE T-SHIRTS WITH " MY THERORY IS....." I AM .

Yeah Iv had the retarded 4.0 distributors, on mine I was able to remove the pin on the gear and spin the gear 180 degrees and it ended up being perfect

That engine sounds terrible. Why not have the person who installed it fix it?

She’s so beautiful???!

Said the brakes weren’t working it’s the booster bad causing vacuum leak

Did he just say he doesn't use a engine code reader??

Anybody have any tips? I have a 2001 wj (grand Cherokee) 4.0 it dies sometimes and it’s random the fuel tank ain’t dirty it’s getting spark and air but the fuel pump isn’t out

Pull the head

Fuel pressure regulator