jakes

I was wondering what the highest mileage you guys saw with these 3.8's in the JK's. I went to service today and chatted with one of the mechanics and we got talking. He said that the 3.8 was a solid engine and that they will not die. He said almost as good or even better than the 4.0. Don't really know much about engines but he said that these should last a long long time. He said he had seen 2 caravans almost clock in at 300k and another almost at 400k. Of course those were probably 3.3s and I know that the JK's engine is a bored out 3.3.

XBlacky08X

Do yourself a favor and search "oil consumption". Mine on the other hand has been fine.. So far.

jakes

Oh I wasn't talking about gas or motor oil consumptions I was just wondering what was the highest mileage you've seen on a JK.

rickyj

Just talking about mileage, there isn't a DOUBT that a few Wranglers will hit 3-400k. Outliers are a bad way to judge longevity though.

I don't know how many people I have heard just dismiss their major problems with their Honda, Toyota, etc - because they "know some guy" who has 500k miles on the odometer trouble free. My cousin needed an engine overhaul on his 4runner at 80k or so and was actually HAPPY about it because, and a quote "since toyota's last forever it was like getting a brand new car".

The 3.8 is underpowered for the vehicles weight. I would think that would prolong the driveline components but put a higher toll on the engine and shorten its life. Given that the 3.8 is a well developed engine, in a vehicle that usually sees pretty light use (on the accelerator anyways) - my guess is an easy 150-200k miles on average. Some way less, some way more.

If mine which is driven easy usually, doesn't leak any oil after three years, and still sounds great at around 47k doesn't last to 150k I would be amazed. My TJ, sold to my Dad, now has 135k on it and is treated like crap. Not to mention it is 15 years behind in technology.

I would be more worried about the Pentastar than the 3.8. New products have issues, even if they are among the biggest development programs that have been.

To get REAL long, who cares? If the vehicle you want to drive burns up engines, transmissions, whatever - you just have to add that to the per mile cost. If you aren't going to buy a vehicle because it's engine burns out 25-50k miles earlier than average you are buying the wrong vehicle. On a per mile basis - any decision that is based on a cost of less than a cent means you are really stretching for justification.

OverKill

I have a 2007 unlimited I bought used on 10/09 with just less than 36,000 miles. I now have over 100,000 and not any issues. I do not have oil burn issue either.

Jeep Unlimited

One can't judge longevity of any engine based on reports of others. Sure, the 4.0 was a great engine and I personally have seen them with 300k but I have also seen them rebuilt before 100k. That's the way it is with any mechanical device. Eventually something will fail.
Just maintain the engine the best you can, as close to factory recomendations as possible if you are truley concerned about engine life, and enjoy. You want it to last longer, leave it factory. You want to shorten the life but enjoy the ride, put on adders. There are too many factors involved.

5Gesus

194,000 on my 2007 JKU and runs like new. Have a front crankshaft seal leaking, but does not burn oil. Superchipped mine and run the 91 octane profile and it runs much better than the factory tune.

user 729872082

I used to drive mine as a daily driver but now it is driven for fun. Around 85K and runs great. No leaks and no smoke.

JFish'n

The engine in my 07 made it to about 175k until the rod bearing spun.

It made one heck of a deal for me to pick up as a project, however the failure seem'd to be related to lack of maintenance.
It had an antifreeze leak, Oil leak, original plugs and wires, engine was sludge up badly from what appears to be lack of oil changes.

Wild guess is the oil got low, also possible it was running hot due to the antifreeze/coolant leak coming out of the plastic water outlet housing.




I would suggest not using that oil change light crap either, do it via mileage instead.
asking for sludge if you run it too long (IMO).

user 729872082

Wow original plugs and wires? That is amazing!