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montechie

montechie

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Some interesting answers, but nice high-level info. I agree about what he said with the 4.0, both the strengths and weaknesses. It's been pretty simple for me to work on, the '05-06 Rubicons had more electronics in the form of sensors, but not too many. I already preemptively replaced the cooling system at 120K (with OEM) based on others' experience on what breaks on the trail.

Some interesting confirmations on the JT/JL issues that I see on this forum. I was expecting electrical mods to be the #1 warranty rejection, just because of the challenge of properly debugging e-gremlins and the interrelationship of electrical components.
 

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Some interesting answers, but nice high-level info. I agree about what he said with the 4.0, both the strengths and weaknesses. It's been pretty simple for me to work on, the '05-06 Rubicons had more electronics in the form of sensors, but not too many. I already preemptively replaced the cooling system at 120K (with OEM) based on others' experience on what breaks on the trail.

Some interesting confirmations on the JT/JL issues that I see on this forum. I was expecting electrical mods to be the #1 warranty rejection, just because of the challenge of properly debugging e-gremlins and the interrelationship of electrical components.
Have you heard of any issues with the 05-06 4.0 OPDA (oil pump drive adapter) failures resulting in catastrophic engine failure? I noticed the Jeep expert also did not address the early TJ 4.0 cylinder head failure due to weak castings that wasn't resolved until 2003.
 
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montechie

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Have you heard of any issues with the 05-06 4.0 OPDA (oil pump drive adapter) failures resulting in catastrophic engine failure? I noticed the Jeep expert also did not address the early TJ 4.0 cylinder head failure due to weak castings that wasn't resolved until 2003.
I actually haven't come across the OPDA issue. I had a transmission pump failure at around 120K and 17 years, and some sensor failures around the same time (cam, map) that I believe are specific to the Rubicon 4.0s of the time.
 

Lunentucker

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He said the same thing about cold air intakes that I had already deduced on my own. The PCM controls the air/fuel mix and the factory filter setup gives it more air than it can use.
Unless you can change the tuning you're not getting anything but a different sound.

 
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There are two main factors in reliability, the inherent design/manufacture and maintenance. We've had s lot of high mileage vehicles in my family, Honda, Jeep, VW, Toyota, and the common thread is that they were all purchased new and well cared for. Scheduled maintenance by the book and hitting wear items and issues promptly are key. The jeep is nice for being relatively easy to work on, plenty of space, robust design.
 

ShadowsPapa

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and the factory filter setup gives it more air than it can use.
That's a "duh".
Anyone who has calculated cams (lifts, durations, scavenging), displacements and CFM requirements would know and yet others will say "but this guy on youtube proves it works" or similar bunk.
Only if other things are changed, and the tune is changed and you race it at high RPM.
The engine is a pump. You can figure tha air needs pretty easily. And the 3.6 is not a big pump.
Cubic Feet per Minute (of air pumped by the engine). The air filter and housing, etc. can handle all this engine can use.
I suppose one could put a sensitive vacuum gauge in the air intake between throttle body and filter media to prove it.
 

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Him saying 385,000 miles on a Jeep in about a year was a head scratcher.
I wondered about that. I suppose someone who drives his Jeep constantly to Alaska, The Yukon, Southern Mexico and back could put that many miles on a Jeep in a year.

I'm reminded of a Navy buddy I met in a tech school in Key West. He had driven there from his home town near Seattle. He drove a 1971 Dodge Demon with a Slant Six. That's one serious road trip!
 

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I wondered about that. I suppose someone who drives his Jeep constantly to Alaska, The Yukon, Southern Mexico and back could put that many miles on a Jeep in a year.

I'm reminded of a Navy buddy I met in a tech school in Key West. He had driven there from his home town near Seattle. He drove a 1971 Dodge Demon with a Slant Six. That's one serious road trip!
It's about 44 mph 24/7/365
 

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It's about 44 mph 24/7/365
There's that danged math, and logic, again.
You forgot about eating and potty time and sleeping in a RTT now and then.
 
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40s on a Dana 44?
I wish that speed question had a followup. With axle shaft, u-joint upgrades and trussing maybe? People compete on those setups, but usually with way lighter rigs. At some point after all the work on a 44 you may as well have spent the $ on a 60 or similar. Not sure if you are doing your own work though.

Or keeping it as a mall crawler and passing the damage to the next owner...
 

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I wish that speed question had a followup. With axle shaft, u-joint upgrades and trussing maybe? People compete on those setups, but usually with way lighter rigs. At some point after all the work on a 44 you may as well have spent the $ on a 60 or similar. Not sure if you are doing your own work though.

Or keeping it as a mall crawler and passing the damage to the next owner...
There is no way I’d put 40s on a Dana 44, trussed or not.
 
 



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