jscribn1

Finally going to purchase our first Jeep. Looking at a 4 door Wrangler. I have friends who say to stay away from the 3.8L V6 and to buy 2012 or newer with the 3.6L. It'll be strictly a recreational vehicle towed behind the motorhome, trail driven and used for hunting etc. I'll lift it with 35's as I want a capable wheeler just not going to be doing anything crazy. Is there a model/year that anyone would say for sure to stay away from or any other advice you can give to a newbie? Any and all suggestions are appreciated.
Justin

LidLess07X

The 3.8 is a good engine with a proven history. It is not a powerhouse and may present some challenges on mountain passes or if you are towing something.

The 3.6 has much more power but has yet to be proven in my eyes.

I have owned two of each without any problems.

The 2012's were known to have clogged heater cores due to casting sand being left in the engine block and also cracked manifolds that are not a cheap fix.

Regearing helps the most, along with a programmer, SprintBooster, and of course supercharging. Ripp Mods is probably the best for supercharging.

Exhaust and Intake will net you absolutely no gains in power.( except with supercharging or turbo)

I would go with any year except 2012.

Arson

I gotta 3.8 over 120k on it. No problems to date. Just check your oil regularly and your'e all good.

resharp001

I'd stick with '13+. Test drive one with the 3.8L, then one with the 3.6L. You can only fix so much with gearing. I've not owned a 3.8L myself, but also seems that older 3.8L's like to drink a lot of oil. I'd agree with the previous comment about the '12's, and add that they updated the seats in '13 (a big improvement).

ronjenx

The blocks are die cast; no sand involved.

LidLess07X

Not disagreeing with you because I may be wrong. Can you clarify ? I thought there was a lot of talk about this in 2012 and "casting sand" being the problem.


Also as another poster mentioned, the 3.8 is known to use oil but no rhyme or reason as to why some do and some don't. Neither of my two used oil but I followed the break in procedures and don't really beat on my Jeep.

rob_engineer

Check out the how many miles on your pentastar thread. My 2012 jku Sport has been fantastic. Now has 92,000 miles on it, trouble free. I'd say it's proven. Yes, some 2012's have a left side head issue, which resulted in a warranty extension for that to 150,000 miles. I've towed a trailer approaching 5000 pounds with my 2012 all over the east coast. It's still as strong as the day I got it. My advice for the OP. You say you will put 35's on it. Then you seriously need to do homework about gearing. 3.21 will be pitiful. 3.73 will be slightly tolerable. Better for you would be to look for a 2012+ rubicon with 4.10 gears.

rob_engineer

I've been following this forum every day for over 5.5 years, since I got my 2012 jku. I do not recall a rash of issues with cracked manifolds on the pentastar. In fact, I cannot remember a single post about that. I don't even think our pentastar jeeps have exhaust manifolds. Are you sure about your statement? Are you talking about the intake? As for the sand, yes, some people posted about something in the overflow reservoir that resembled sand. Clearly any issue about that on a 2012 would have been taken care of by now.

mr72

Cylinder head cracks are really the only meaningful issues with the '12+ pentastar JKs that seem to be abnormal in terms of overall reliability. The incidence of the head cracking is very low but >0 so it gets a lot of attention on the internet. I've heard many other alarming problems reported early in the engine's life such as oil pumps going bad before 100K etc. which would freak me out but Jeep guys seem to take all this as ordinary expected reliability of a Jeep.

The 3.8 was universally panned as insufficient for power especially for the unlimited, and also has poor fuel economy in case that matters. If you were going to stick with 29" tires on 16" wheels and no "wheeling" then I'd think there's probably no reason to avoid the 3.8 but given your suggestion of running 35" tires (!) and a lift, I think you are going to be horribly disappointed with a 3.8. Even my MT 2015 with 33" tires and 3.73 gears is not going to impress you with its performance... low-range bails it out when push really comes to shove but it's merely adequate for daily/highway/urban driving. I would think a 3.8 would be far less than adequate in today's world of 80mph speed limits.

Jeep JKs all have probably slightly below average American car reliability which is to say they are far less reliable than a typical Japanese or Korean car but for flag-waving rednecks they are fine. The most unreliable part of your JKU is going to be effects of your cosmetic choices (lift, big tires, etc.), which will introduce extra stress on suspension, axles, etc. and result in premature failure of that stuff. Off-roading regularly will dramatically reduce reliability on a per-mile-driven basis. You know reports of Pentastar JKUs with 100K+ trouble-free miles are abundant, but I wouldn't expect the same result for a tow-behind vehicle which experiences most of its miles driving off road. So YMMV, and yours more than others.

Anyway, I'd still recommend a Pentastar JKU and the latest model you can possibly afford in order to get the improved cylinder head design that might have less chance of cracking. Plus the interior of the later Mk2 JKUs is much better than the older ones, in case that matters to you. And a newer one has less chances of prior-owner abuse, like frequent off-roading, rust, etc. Frankly I'd personally never buy a used Jeep for anything that I had to rely on myself daily, plus the resale value is so high that it makes little sense to buy used anyway. If I were in your situation I'd be looking for a TJ or LJ.. or maybe even an XJ if you are not totally sold on going without top and doors and you really need 4 doors. An XJ with 60K miles and a manual transmission is a tremendous value compared with a JKU.

IMHO, and of course my opinions are rather unpopular here on JKF.

jchappies

The 3.8 is a good motor, its the trans that is limited in the auto(4spd vs 5spd). The 12+ has a lower 1st gear so your going to feel like you have more power. The 3.6 has 40 more HP than the 3.8 at the flywheel but the 3.6 also revs higher.
As a dedicated trail rig either would work, just depends on how much you have to spend on one and what mods you want to do.