Operation Phoenix

[macleanflood]

Bought a fresh Dana 30 4.88 ring and pinion. Didn't want to spend the money on 5.13s.

Replaced the driveshaft u joints. They had an 1/8" of up down play. Interestingly one cap kinda had grease and the other side was bone dry. Pretty consistent across both joint and sides. Probably need to add greasing these joints to the annual tear apart the JJs and grease them activity. One cap fell apart on removal. Ran some weld bead inside to shrink it and it came right out.

Didn't order new carrier shims. Mistake. Original ones were messed up enough to complicate reinstallation. New ones will take a week to arrive. I probably have some so tomorrow I need to search my stashes.

Also probably discovered why my front locker was intermittent. Couple of broken spots in the insulation. Slipped shrink tube over to repair.

-Mac

 

[macleanflood]

Ok so a couple of seperate threads to mention...

This was "fixing" my 231J that started hemorrhaging ATF coming back from Moab. Front half of the case was cracked. Still oozes fluid and I have a replacement and am debating a JB SS SYE and new rear shaft.

Thread 'Chasing 231J leaks'

Jun 27, 2025

On my way home from Moab my 231J started hemmoraging fluid.

I've since replaced the front output seal and the shifter o-ring and retention ring.

It's still leaking.

Thinking it might be this...which I believe is a shift detent spring and ball.

Anyone have any idea what sized o-ring? I have an assortment...might have something.

Thoughts on this being the source? I think I need to check my vent too...might be over pressurizing.

-Mac

• macleanflood
• Replies: 150
• Forum: TJ General Discussion

• 

Then replaced my chipped front gears. Used Yukon. Should have done revolution.

Thread 'Gear pattern check'

Jan 3, 2026

Dana 30. Broke three teeth on the original 4.88s I had in there. Figured I could swap in a new set with minimal changes. Bzzt. Mistake was probably buying cheap Yukon but here I go.

Backlash is in spec. My read is the pinion is way shallow. But I wanted an experienced opinion before I pull the pinion.

-Mac

• macleanflood
• Replies: 47
• Forum: TJ General Discussion

That didn't solve a noise I was chasing...but pulling the driveshafts isolated it to the rear...and the centering yoke was toast...so that's fixed.

I want to install my iBooster...but I need to make an aluminum adapter plate and don't have the CAD skills to draw it up and send to someplace like send cut send.

Meanwhile I picked up a 97 XJ 4.0 engine.

Mostly because a few folks mentioned my idle sounded like cracked pistons. And I don't want to tear into my engine and have it down for a long time waiting for parts or machine shop work.

Started pulling the "new" engine apart. One...this thing is covered in oil. I brought it home in the middle of the night or I would have swung by the car wash and degreased it.

Head looks good. Rockets, pushrods. Everything is very dirty. Light rust on some of the valve stems.

Heavy corrosion in the water jacket... nobody was running coolant in this block.

630 head. Same as mine. Same intake...same casting number.

Planning on having the intake cerrokoted.

Probably have the head fly cut and the blocked knocked down a touch for more compression.

New pistons, rings, bearings, valves maybe if these don't clean up. Definitely valve seals.

Thinner head gasket. Which probably means shorter pushrods by whatever thou I reduce things by.

Lifters? Maybe 1.7 rockers? RV cam? I don't want to spend too much on this. Power is too expensive on a 4.0. I just want reliable.

Definitely a water pump, timing chain and oil pump.

Pulling the oil pan tomorrow.

Feel free to suggest a shopping list.

-Mac

 

[GoldenGorilla]

Ok so a couple of seperate threads to mention...

This was "fixing" my 231J that started hemorrhaging ATF coming back from Moab. Front half of the case was cracked. Still oozes fluid and I have a replacement and am debating a JB SS SYE and new rear shaft.

Thread 'Chasing 231J leaks'

Jun 27, 2025

On my way home from Moab my 231J started hemmoraging fluid.

I've since replaced the front output seal and the shifter o-ring and retention ring.

It's still leaking.

Thinking it might be this...which I believe is a shift detent spring and ball.

Anyone have any idea what sized o-ring? I have an assortment...might have something.

Thoughts on this being the source? I think I need to check my vent too...might be over pressurizing.

-Mac

• macleanflood
• Replies: 150
• Forum: TJ General Discussion

• 

Then replaced my chipped front gears. Used Yukon. Should have done revolution.

Thread 'Gear pattern check'

Jan 3, 2026

Dana 30. Broke three teeth on the original 4.88s I had in there. Figured I could swap in a new set with minimal changes. Bzzt. Mistake was probably buying cheap Yukon but here I go.

Backlash is in spec. My read is the pinion is way shallow. But I wanted an experienced opinion before I pull the pinion.

-Mac

• macleanflood
• Replies: 47
• Forum: TJ General Discussion

That didn't solve a noise I was chasing...but pulling the driveshafts isolated it to the rear...and the centering yoke was toast...so that's fixed.

I want to install my iBooster...but I need to make an aluminum adapter plate and don't have the CAD skills to draw it up and send to someplace like send cut send.

Meanwhile I picked up a 97 XJ 4.0 engine.

View attachment 674187

Mostly because a few folks mentioned my idle sounded like cracked pistons. And I don't want to tear into my engine and have it down for a long time waiting for parts or machine shop work.

Started pulling the "new" engine apart. One...this thing is covered in oil. I brought it home in the middle of the night or I would have swung by the car wash and degreased it.

Head looks good. Rockets, pushrods. Everything is very dirty. Light rust on some of the valve stems.

Heavy corrosion in the water jacket... nobody was running coolant in this block.

630 head. Same as mine. Same intake...same casting number.

Planning on having the intake cerrokoted.

Probably have the head fly cut and the blocked knocked down a touch for more compression.

New pistons, rings, bearings, valves maybe if these don't clean up. Definitely valve seals.

Thinner head gasket. Which probably means shorter pushrods by whatever thou I reduce things by.

Lifters? Maybe 1.7 rockers? RV cam? I don't want to spend too much on this. Power is too expensive on a 4.0. I just want reliable.

Definitely a water pump, timing chain and oil pump.

Pulling the oil pan tomorrow.

Feel free to suggest a shopping list.

View attachment 674189View attachment 674190View attachment 674191View attachment 674192

-Mac

That piston on the new motor doesn't look stock with the d-shaped relief. You'll want to measure the bores carefully to get the right size. Don't love the rust in the coolant channels.

No to RV cam. If your lobes are good, keep running it. Pull the lifters and keep them in order. Consider the HS 1.7 roller rockers.

As someone who drives their TJ the long haul, I'd absolutely do at least a Clegg Stage 1 4.6 stroker. The difference in the cost of the crank is marginal in the scheme of everything else and doesn't neccessarily require any addional machining if you're OK with a lower stock-like compression. Otherwise getting the deck shaved to bring the piston level at TDC is minor work. You'll gain a ton of drivability improvement, tons of low end torque and probably not lose any fuel economy.

 

[macleanflood]

How much should I shave the deck? And then use the OEM thickness head gasket - I think that's .040 or get a I think thinner.020?

Assuming at that point I need shorter pushrods by that much length since the rockers are non adjustable.

Do I need 24 lb injectors?

-Mac

 

[GoldenGorilla]

How much should I shave the deck? And then use the OEM thickness head gasket - I think that's .040 or get a I think thinner.020?

It's just going to depend on some specifics to your package. There is a thin Cometic MLS head gasket, which might also give you what you want. You're generally going to deck the block in the range of 0.015"-0.030". A relatively small amount, but it helps with quench which reduces the risk of pre-detonation. Rod length, pin height and the stroke all affect this calculation. There are 2 formulas, but the one Clegg sells in the kit uses the 4.2L type crank, with 4.0L rods and pistons with the pin height for this combo, but it sits a little down in the hole (as does the stock setup).
This is outdated on source stuff, but it provides the basic on the math and is a quick read.

When you have the numbers from Clegg, you can plug them in here.

I would pay for the balancing and the better bearings.

Assuming at that point I need shorter pushrods by that much length since the rockers are non adjustable.

Typically not necessary. Your motor will have hydraulic lifters and this tiny adjustment is typically within the self-adjusting range of the lifter.

Do I need 24 lb injectors?

Yes. It'll run on closed loop with stock injectors, but you'd go lean on WOT on open loop. Clegg sells a set at a good price, but there are plenty of other offerings out there. This is generally "good enough" with the factory fuel tables and really the only option for older XJs with the ODBI Renix PCM. But you can also get some benefit by tuning the open loop with a wideband O2.

If you go with their Stage 3 "5.0L" kit, you'd likely need a larger 29, 35, or 42 lb injector. Some math is required. There is a lower limit on the injector pulsewidth at cruising vs the demand on WOT to balance. Roadtripping is not the same as dragstripping.

You'd also benefit from having some additional control with HP Tuners, but it'll run without. Unfortunately they switched over the MPVI4 and so far are not supporting our JTEC computers with the new device. You need an MPVI3.

 

[macleanflood]

So right now I have $615 in parts in my Rock Auto cart.

The Stage 1 Clegg kit plus injectors and balancing and a crank pulley is $1933.

Add in a MPVI3 at $400 plus credits and a Flyin Ryan tune.

That would put me almost $3k in.

I'd almost rather throw that at an LS.

Need to see if I can even find a machine shop in the area to deck the block and head.

-Mac

 

[John Cooper]

So right now I have $615 in parts in my Rock Auto cart.

The Stage 1 Clegg kit plus injectors and balancing and a crank pulley is $1933.

Add in a MPVI3 at $400 plus credits and a Flyin Ryan tune.

That would put me almost $3k in.

I'd almost rather throw that at an LS.

Need to see if I can even find a machine shop in the area to deck the block and head.

-Mac

Find a machine shop to magnaflux the block and head also.

If that all looks well and you decide to build it, line bore the cam journals too.

 

[macleanflood]

Southworth Machine shop can fly cut my head for $104 and the block for $140.

Adding up quick!

-Mac

 

[John Cooper]

Southworth Machine shop can fly cut my head for $104 and the block for $140.

Adding up quick!

-Mac

You need to magnaflux for cracks also, that's usually or used to be cheap.

Time wise, if they line bore the cam and then install bearings that would be in your favor.

 

[Wildman]

I'd almost rather throw that at an LS.



-Mac

Damn dude I'd have to disown ya.... And you'll be about X3 that amount if you try a LS swap....

Cheaper? Easy Peasy.... Magnum V-8 swap.. And you can keep your AX15 too if you want.... I've got a 5.9 sitting here.... Free if you come get it...
Have a stroker crank for it too.... And a built 46RE... Make you a HELL of a deal....
Already sold my old wiring harness but it's not hard to blend the two harnesses.

And quality rebuild is gunna cost you more than you think... Period.

 

[macleanflood]

All of these are great ideas. All of these cost way more than my budget. All of these are better solutions. I'm pretty sure I have cracked pistons and just want to address that issue before I wreck a block and end up stranded somewhere.

My gut instinct tells me to do the piston swap on a fresh block so I can prep everything ahead of time.

-Mac

 

[Irun]

You've got a good source of knowledge, and some parts, for a 5.9 swap relatively close by. Given the cost of machine work and parts on the 4.0, it might be worth talking to Rick. You've certainly got the skills to make it happen!

 

[Wildman]

All of these are great ideas. All of these cost way more than my budget. All of these are better solutions. I'm pretty sure I have cracked pistons and just want to address that issue before I wreck a block and end up stranded somewhere.

My gut instinct tells me to do the piston swap on a fresh block so I can prep everything ahead of time.

-Mac

If you're rebuilding an engine I-6 or V-8 isn't much difference in cost...

The most expensive part would be a Dakota V-6 belhousing to keep your AX15...


Budget wize I'd do the Stage I stroker build... Just my $0.02 worth... But for that same $3K you could have a V-8...

But as you know for every mod you do another item crops up needing to be changed/modified/improved.....

 

[lBasket]

V8 swap V8 swap

 

[Wildman]

V8 swap V8 swap

Step Up son..... Yours is a prime candidate for a Magnum swap too...

 

[lBasket]

Step Up son..... Yours is a prime candidate for a Magnum swap too...

I already have a fast car. And enough engine swap headaches

 

[Wildman]

I already have a fast car. And enough engine swap headaches

V-8 into Jeep isn't about FAST..... Mo'Power isn't always related to speed....

 

[lBasket]

V-8 into Jeep isn't about FAST..... Mo'Power isn't always related to speed....

I think I should just wait til my truck gets hit and use the LQ9 in it

 

[Wildman]

I think I should just wait til my truck gets hit and use the LQ9 in it

Ya'll know how I feel about a Lame Shit in a TJ.... I don't lose my shit over it but...

 

[Apparition]

Ya'll know how I feel about a Lame Shit in a TJ.... I don't lose my shit over it but...