How far can a 4.0 go?

[HDRider]

Have to say me and my TJ are getting to be friends. Been a long time since I just jumped into a 4 wheeled something and took a drive for the joy of the drive.

I was out piddling with it. I have been doing the additive thing. Started by putting Marvel Mystery in the first oil change. Ran than about 500 miles and changed the oil and filter again. Then I stared using Lucas fuel additive and did about four tanks of that through it. I have now ran two tanks with Marvel in the gas. Just finished running a can of Sea Foam down the carb slow and easy, adding a little at a time to get that white smoke out the tail pipe.

Someone has to buy all those miracles in a bottle at the auto parts store. I am that guy.

I have made a practice of taking it to about 4,200 rpm a couple of times a week to blow it out.

Anyway, mine 4.0 has 154k on it.

Assuming reasonable care, how far do you think these things can go until it has to be rebuilt?

 

[Stinkbug]

Have to say me and my TJ are getting to be friends. Been a long time since I just jumped into a 4 wheeled something and took a drive for the joy of the drive.

I was out piddling with it. I have been doing the additive thing. Started by putting Marvel Mystery in the first oil change. Ran than about 500 miles and changed the oil and filter again. Then I stared using Lucas fuel additive and did about four tanks of that through it. I have now ran two tanks with Marvel in the gas. Just finished running a can of Sea Foam down the carb slow and easy, adding a little at a time to get that white smoke out the tail pipe.

Someone has to buy all those miracles in a bottle at the auto parts store. I am that guy.

I have made a practice of taking it to about 4,200 rpm a couple of times a week to blow it out.

Anyway, mine 4.0 has 154k on it.

Assuming reasonable care, how far do you think these things can go until it has to be rebuilt?

I guess it depends on how it was cared for and driven the first 153k miles…

 

[Jerry Bransford]

You can stop using all those additives, especially so much of them, they're really of no benefit. They're just big profit-makers for their manufacturers and retailers. Not to mention the EPA requires ALL US gasolines to contain adequate fuel cleaning additives to keep the fuel system clean. That wasn't always true, we needed fuel injector cleaners up until the mid-eighties when the EPA started mandating them in ALL US gasolines. Not just Tier One gasolines, all of them.

 

[L J]

Anyway, mine 4.0 has 154k on it.

Assuming reasonable care, how far do you think these things can go until it has to be rebuilt?

Long enough for you to save up the money to:

• rebuild if you are capable
• buy a reman and swap it in

If there are no indications of an issue, continue with routine maintenance and enjoy. As a second, third, etc vehicle it could easily go another decade.

 

[HDRider]

I wasn't really asking specifically about my 4.0, but about the 4.0 in general.

 

[chudlet]

Well, mine is sitting at 325K ish and I have heard of a few others in the 400K range. Provided it was taken care of and it was a Wednesday when it was assembled, I think you can expect a pretty long and serviceable life out of it.

 

[TheBoogieman]

This is the only additive I'll use in any of my Jeeps. It keeps the engine 20 degrees cooler, gets me 28 mpg and freaks out my stoned friends when I tell them I switched their "Brittney Griner oil" and they're vaping with it right now. Too soon?

 

[Jerry Bransford]

This is the only additive I'll use in any of my Jeeps. It keeps the engine 20 degrees cooler, gets me 28 mpg and freaks out my stoned friends when I tell them I switched their "Brittney Griner oil" and they're vaping with it right now. Too soon?
View attachment 348759

Nothing like Snake Oil to cure whatever ails you or your engine!

 

[Sancho]

Have to say me and my TJ are getting to be friends. Been a long time since I just jumped into a 4 wheeled something and took a drive for the joy of the drive.

I was out piddling with it. I have been doing the additive thing. Started by putting Marvel Mystery in the first oil change. Ran than about 500 miles and changed the oil and filter again. Then I stared using Lucas fuel additive and did about four tanks of that through it. I have now ran two tanks with Marvel in the gas. Just finished running a can of Sea Foam down the carb slow and easy, adding a little at a time to get that white smoke out the tail pipe.

Someone has to buy all those miracles in a bottle at the auto parts store. I am that guy.

I have made a practice of taking it to about 4,200 rpm a couple of times a week to blow it out.

Anyway, mine 4.0 has 154k on it.

Assuming reasonable care, how far do you think these things can go until it has to be rebuilt?

Though obsolete, the 4.0 is really known for being bullet proof. Regular maintenance will likely get you into the high mileage catergory.

Try to stay on top of the ticks, taps, and oil leaks.

IMO The cost of gas is the 4.0 killer.

 

[Mousy Orla]

Long enough for you to save up the money to:

• rebuild if you are capable
• buy a reman and swap it in

If there are no indications of an issue, continue with routine maintenance and enjoy. As a second, third, etc vehicle it could easily go another decade.

My plan too when my engine goes, gonna rebuild, reman and swap or find another powerplant. Right now, I kinda want to keep things fairly stock with minor and more modern upgrades where possible.

 

[TJ Jim]

Just saw a rhd for mail carriers for sale on Craigslist. 486,000 miles. Didn’t mention any rebuild or anything. I’m sure it had brakes replaced once maybe even twice.

 

[TexasTJ2004]

Just finished running a can of Sea Foam down the carb slow and easy, adding a little at a time to get that white smoke out the tail

I thought we don’t have a carburetor

 

[TexasTJ2004]

I do use these additives:
New BG 44K Platinum, EPR, MOA https://a.co/d/9fOheVl

Any professional garages and dealers also use these. The EPR works, and it cleans the gunk from your oil. You add into the oil, run in for 10 minutes at 1200 rpm and drain the oil.
The 44K is a the fuel system cleaner that dealership would run.
The MOA is an additive for oil, that you might skip if you want to.

 

[AndyG]

To answer your question the engine is so durable even about two decades post production we still aren’t sure-

Even in the carbureted years the engine was a stand out for durability

I have seen a few random failures that happened before their time- But for the most part the engine is easily going to go between 300,000 and on up to 500,000 or more miles with any maintenance and is going to really outlast most everything else on the vehicle-

I had a Ford 7.3 diesel with the mentality that I would drive it forever but when you start getting to the point that there are springs sticking up out of the seats And the ignition switch falls out of the steering column and the gearbox breaks off the frame you start losing confidence in the whole package.

Often, people have changes of heart or circumstances or just get ready for something new long before the thing really ever dies.

 

[chudlet]

To answer your question the engine is so durable even about two decades post production we still aren’t sure-

Even in the carbureted years the engine was a stand out for durability

I have seen a few random failures that happened before their time- But for the most part the engine is easily going to go between 300,000 and on up to 500,000 or more miles with any maintenance and is going to really outlast most everything else on the vehicle-

I had a Ford 7.3 diesel with the mentality that I would drive it forever but when you start getting to the point that there are springs sticking up out of the seats And the ignition switch falls out of the steering column and the gearbox breaks off the frame you start losing confidence in the whole package.

Often, people have changes of heart or circumstances or just get ready for something new long before the thing really ever dies.

Lol my 91 Dodge Cummins is the same way. Can't talk myself into getting rid of it yet though.

 

[AndyG]

Lol my 91 Dodge Cummins is the same way. Can't talk myself into getting rid of it yet though.

Mine went from something I cherished and would hardly let other people drive to something that I would make people drive so I wouldn’t have to-

It had 440,000 miles when we parted ways.

Your old school Cummins engine is just absolutely the bomb.

 

[TheBoogieman]

Any professional garages and dealers also use these.

Their only objective is to empty your wallet. 🤫

 

[TexasTJ2004]

Their only objective is to empty your wallet. 🤫

BG EPR works for sure. After one cleaning cycle is ticking much less. I think that it cleans the oil passages, which impacts the lifters.

 

[Mousy Orla]

My TJ runs and is nearing 200k miles now, it's at like 196.5k miles currently. I assume the previous owners beat this Jeep to hell too.

 

[Badgerbiter]

228. Original miles (engine, tranny etc) Plenty of new parts. Mostly steering, u-joints axles, shocks, springs, sensors, etc.
Always upgrade if possible..
Lockers (pneumatic) front and rear.
I drive it every day. Runs like a top (knock on wood).
lot’s of good info on this forum..