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How far can a 4.0 go?

HDRider

TJ Enthusiast
Joined
May 26, 2022
Messages
113
Location
Arkansas
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

TJ Enthusiast
Supporting Member
Joined
Apr 9, 2016
Messages
303
Location
Huntington Beach, Ca
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…
 
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Jerry Bransford

TJ Guru Moderator
Staff Member
Supporting Member
Joined
Nov 9, 2015
Messages
24,393
Location
Fleming Island Florida
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

Ranchos aren't real
Supporting Member
Joined
Nov 26, 2017
Messages
4,097
Location
Dumont Dunes
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.
 
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chudlet

Member
Supporting Member
Joined
Apr 18, 2022
Messages
75
Location
N Idaho
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

Disturbed American
Supporting Member
Joined
Jan 1, 2019
Messages
6,380
Location
C-Ville VA
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?
snake_oil_.jpg
 

Jerry Bransford

TJ Guru Moderator
Staff Member
Supporting Member
Joined
Nov 9, 2015
Messages
24,393
Location
Fleming Island Florida
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! :ROFLMAO:
 

Sancho

TJ Addict
Supporting Member
Joined
Jan 17, 2018
Messages
1,787
Location
San Diego, CA, United States
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.
 
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Athena

Member
Joined
Feb 8, 2022
Messages
89
Location
Chesapeake, VA
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.
 
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TJ Jim

TJ Enthusiast
Supporting Member
Joined
Feb 12, 2021
Messages
654
Location
Tennessee
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.
 
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TexasTJ2004

I love my TJ
Supporting Member
Joined
Aug 8, 2021
Messages
301
Location
77380
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

TJ Guru
Lifetime Supporting Member
Joined
Jul 30, 2018
Messages
12,441
Location
Alabama
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.
 
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chudlet

Member
Supporting Member
Joined
Apr 18, 2022
Messages
75
Location
N Idaho
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

TJ Guru
Lifetime Supporting Member
Joined
Jul 30, 2018
Messages
12,441
Location
Alabama
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.
 
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Athena

Member
Joined
Feb 8, 2022
Messages
89
Location
Chesapeake, VA
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

TJ Enthusiast
Supporting Member
Joined
Sep 29, 2020
Messages
108
Location
Cle Elum, WA
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..