4.0 WJ nears 200K: should any original parts be replaced for preventive maintenance? - JeepForum.com
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post #1 of 6 Old 06-22-2021, 10:28 AM Thread Starter
Jeepsmsc2
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4.0 WJ nears 200K: should any original parts be replaced for preventive maintenance?

Owned a 2003 4.0 WJ since new. Now have 192K miles. I've kept up with maintenance over the years. Still on original engine and transmission and they are working fine.

Now that I'm approaching 200K miles, should any original parts be replaced for preventive maintenance? Or if they've made it this far, keep driving and let them fail?

I've replaced some parts over the years, but are there any original parts that are statistically likely to fail in a 4.0 WJ that should be replaced if they haven't already?

For example, the below example items that come to mind that are still original on my vehicle. I haven't observed any warning signs that suggest they are failing.

1. Crank Position Sensor
2. Alternator
3. Transmission governor pressure sensor and solenoid and accumulator spring
4. The sensors screwed into the throttle body (TPS, IAC, MAP). I did remove the throttle body last year and clean it and the sensors with carb cleaner.
5. Power steering / brake original

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post #2 of 6 Old 06-22-2021, 10:30 AM Thread Starter
Jeepsmsc2
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Also - the 4.0 motor mounts are original.
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post #3 of 6 Old 06-22-2021, 12:36 PM
Dust Devil
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My crank position sensor failed. Evidently it was heat related and some times it would have to cool completely before it would restart after it died (while I was driving). Not a nice failure mode but everyone says only buy OEM replacements because the generics don't last. The problem is they are expensive, over $100 just for the part, not installation.

Mine is replaced now and should be good for another 10+ years but I'm slightly worried that when that day comes, Mopar may have already quit making crank position sensors for 30+ year old WJs.

I don't know how likely that is but with the mileage and age of your Jeep, I would probably be thinking about buying one to put away. I should probably be thinking about buying a cam position sensor too, maybe TPS. I should probably try to grab a couple matching junkyard PCMs to have flashed as spares also.

It just depends on how long you want to keep it going and how much longer parts cars are going to be in salvage yards.

I think 3-4 years ago was the time to get in to a WJ really cheap and Covid has kind of screwed that up. I'm a bit late to the party but it's still cheap compared to the alternatives. My plan is to get the parts and spares I think I'll need in the next few years and try to make mine a long term project car where I will eventually replace/upgrade every part that is prone to failure or hard to get.
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post #4 of 6 Old 06-22-2021, 06:40 PM
WJ60
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Garage
Motor mounts
control arm bushings
u joints
Shocks
steering stabilizer
serpentine belt
belt tensioner
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post #5 of 6 Old 06-22-2021, 07:09 PM
jay-h
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Quote:
Originally Posted by WJ60 View Post
Motor mounts
control arm bushings
u joints
Shocks
steering stabilizer
serpentine belt
belt tensioner
I would go with this list.. but only as a check list. Don't get too deep into fixing stuff that ain't broke.

Sensors sometimes fail, sometimes never fail. You might be inviting more trouble by replacing a working sensor.

Watch the Ujoints but don't change them if they're ok.

Our ZJ has over 250K, the major suspension issues were the control arm bushings and ball joints. But these don't always go bad at that mileage. Just keep an eye on stuff.
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post #6 of 6 Old 06-23-2021, 02:30 AM
Delta0
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Quote:
Originally Posted by Jeepsmsc2 View Post
Owned a 2003 4.0 WJ since new. Now have 192K miles. I've kept up with maintenance over the years. Still on original engine and transmission and they are working fine.

Now that I'm approaching 200K miles, should any original parts be replaced for preventive maintenance? Or if they've made it this far, keep driving and let them fail?

I've replaced some parts over the years, but are there any original parts that are statistically likely to fail in a 4.0 WJ that should be replaced if they haven't already?

For example, the below example items that come to mind that are still original on my vehicle. I haven't observed any warning signs that suggest they are failing.

1. Crank Position Sensor
2. Alternator
3. Transmission governor pressure sensor and solenoid and accumulator spring
4. The sensors screwed into the throttle body (TPS, IAC, MAP). I did remove the throttle body last year and clean it and the sensors with carb cleaner.
5. Power steering / brake original
If it ain't broke . . . . . . . . . .
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