Buying a used JK, how many miles is too many?

zackcj7

TJ Enthusiast
Supporting Member
Joined
Jul 1, 2021
Messages
336
Location
Atlanta, GA
I've had several Jeeps with the 4.0 and know how long they can be expected to last with proper maintenance. What years have what issues to look out for and so on.

But what about buying used JKs? A 4.0 TJ with 150,000 miles would not scare me at all. But what about the V6s in the JKs? I know they had two V6s and the later is more desirable. But is either V6 a motor that can last 200,000 miles without a rebuild? What about the JK transmissions? I tried researching this on the JK forums but the info was all over the place. Some people were saying the JKs are on borrowed time after 100,000 miles and some were saying they had 300,000 trouble free miles on theirs. What is the truth?

No, i'm not getting rid of my TJ for a JK:)
 
  • Like
Reactions: BlueC
Which V6 they changed engines in 2012. One is a 3.8L and the other is a 3.6L. From what I recall I think the 2012+ engine was better. I got rid of my JK in 2011 when my 2 kid was born.
 
Some people were saying the JKs are on borrowed time after 100,000 miles and some were saying they had 300,000 trouble free miles on theirs. What is the truth?

Unfortunately, both scenarios are true. Owners' attention to maintenance and how the vehicles were used substantially contributes to both extremes.

I was shopping for a JK for about a year before ultimately getting a TJ. FWIW, I found this video to be informative relative to the reliability of the newer Jeeps.

 
I've heard the 3.8 used in the 2012 and older can be oil burners. I hear alot of negatives about the jks but the complaints seem to be typical jeep stuff not particular to the jk. If I were shopping I would use the same parameters as buying a used tj.
 
  • Like
Reactions: tworley
2012 or newer to get the 3.6L, but I believe 2012's may have had some issues. It depends what your goals/expectations are. I've dealt with a couple of them.
 
Just my experience here, but in the 7 or so months of owning my 2016 JKUR, I’ve had to replace:

1. Thermostat twice
2. Cooling assembly
3. Power steering pump
4. Having intermittent transmission electronics issues and check engine lights


Keep in the mind this it was pretty clean, it came with a lift and 35s on it, but was never beat on/offroaded by PO.

Not saying all JKs are unreliable, but this just happens to be my experience. If I were ever to buy another JK/JL Jeep, it would only be a 2013+ with way under 100k miles and it would have 40s with it’s looooong wheelbase.
 
  • Wow
Reactions: BlueC
I’ve got a 2015 sport that’s been a fantastic Jeep so far. It’s got 67,000 miles on it, oil changed every 5k and hasn’t had any of the common jk problems. They have oil filter/cooler problems, and if you look in the valley just under the oil filter cartridge if there’s oil beware. Some have had tipm problems which Chrysler seems to be famous for. Mine is a Cadillac compared to my tj. Like they’ve said above the pre 2012’s had oil consumption problems. Oh yeah and some of the post 2012’s have had casting sand left in the heads and stopped up the cooling system. We drove it to California and back after we retired and never had a bit of trouble.
 
Unfortunately, I had early valve (and other ) problems with my purchased new 2014 JK with 38k miles. I dumped it. Nothing serious should be happening that early
 
Last edited:
  • Like
Reactions: BlueC
Before you read just know I have 0 knowledge with jk's. But the 3.6 in those vehciles are pretty reliable engines from what I have seen. My buddy has a 2014 jk he bought new. It has just over 315k km now and just drives the piss out of it. All original components except wear stuff like brakes etc... Regularly tows a boat down to Florida from Ontario. He does have a small tick that developed around the 300k km mark but doesn't seem like anything as it comes and goes, I have never taken a second to even look or think about it! I have also seen lots of high mileage minivans with the 3.6 that run well, my mom has had 2 3.6 engines, and they are peppy little buggers, compared to a tj lol.
 
I bought a brand new 2017 JK and sold it within 2 years.

2012 and newer have the 3.6 Pentastar engine and the 5 speed automatic that is actually a decent transmission.

The Pentastar has issues though:

2012-2013 - Cylinder head issues. This still occasionally occurs in later models as well as I've seen reports of it in 2015 and 2016 models.

2014-2015 - Oil cooler cracking. Chrysler redesigned the oil cooler to make it compatible with both the 3.6 Pentastar and the 3.2 V6 that was in the Cherokee. The cooler was prone to cracking and it would either seep oil into the valley or dump your oil down the back of the engine in seconds leaving you stranded. Finally apparently resolved in late 2015 with around the 6th or 7th revision of the plastic molding.

2016-2017 Probably the best/least problematic years, though my 2017 still had the sludge issue that messes up the cooling system.

2018 JK - Solenoid pack in the auto transmission fails and the vehicle will not start. Can be very random.

All JKs with the Pentastar - Cooling system sludge, milk-jug plastic for the interior parts, poor leather quality (my steering wheel and seat stitching required warranty work). Mine also had electrical issues.

All JKs with the 6 speed manual (not sure if this is JK specific or it could also affect TJs. I know the 2005 NSG370 had a big issue with reverse gear that was fixed for 2006) Popping out of first gear, sometimes also pops out of second and reverse.

So basically, when I went shopping for another Wrangler I didn't even consider a JK or JL. One Fiat Jeep was enough for me.

JMO, but think about what you want from it.

For me, the JK is a better car, but the TJ is a better Jeep.