3.8 JKU Owners

Wes

Wes

Well-Known Member
Joined
Oct 14, 2007
Location
Ridgeway, SC
Used JKU’s are finally getting to a decent price range. Sold my TJ rubicon a while back and I got the itch for another Jeep instantly. I need a 4 door for the crew. Every jeep forum is nothing but hate on the 3.8 sprinkled in with a few rare praises. I realize no one gets online to praise reliability. It’s usually the problem owners. For those of you that have owned a 3.8 wrangler, did you have excessive oil consumption, and was it severely underpowered as all the forums state? I’ve found a low mileage rubicon that I’d consider, provided you guys don’t change my mind. MUCH THANKS!
 
I really think they got so much hate because having 4 doors opened the market to a whole different kind of people. They had no experience of what a Jeep was like and expected way more out of the reality of it. The autos overdrive is a little steep from 3rd gear so you’ve got to regear them a little more with 35+ or heavy 33s to compensate and keep it from searching between gears. It’s 200hp v6 pushing a 4500lb+ box with less aerodynamics than a cow.
 
195k on mine. Owned it since 172k. Yeah, it's underpowered, but it's a jeep, I didn't buy it for the power. Oil consumption? Haven't had to add between changes. I've had to replace valve cover gaskets and intake manifold gasket and replaced one exhaust manifold. Overall I'd say I'm pretty happy with it and really don't understand all the hate either.
 
I've got a 2010 JKU with 150k. No issues with the engine, I can't kill it. It's an automatic transmission. I think a lot of the hate was due to the automatic transmission.

They used a minivan transmission and I guess they didn't bother changing the gear ratios. So, even 33 inch tires will dog it out with 3.73 axles. When I swapped to 5.13 axles gears, my 3.8 came alive.
 
83oldyoda4x4 said:
Biggest complaint is on the highway with the auto the overdrive ratio sucks. It will barely hold speed flat with 33s. But a 5.13 gear solves that.
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Also, 5.13s will still allow you normal highway speeds with decent RPMs on 33 or 35 inch tires.
 
My son's has lived on 35's all its known life. Came with and he keeps rocking the same size. Auto and driven up to Wilkes and Boone a lot when in school. Several trips to Tenn. and Waynesville areas as well, so plenty of hills. He has done some minor work and some I helped. Showing 185k or so and zero major issues. He changes oil on schedule and drives the snot out of it. Small tuner that mostly gives him all sorts of digital engine gauges and doesn't tow. He monitors trans temps and has let it rest before. He put a dirtbike behind it on a insert rack along with gear and noted it struggled badly. Stock gears.
 
I know this thread is a few months old, but figured I would ask here vs starting another..

3.8 JKs seem to fit the current budget better.... On the oil consumption, is there an easy/quick way to check if one is using oil, other than just checking the dipstick? Any other signs? I know some are bad to have oil leaks, and checking for that shouldnt be too hard. Anything else to look for/at if I go to look at some used ones?

Also, I assume the manuals "seem" to have more power, due to the automatic's gearing?
 
If it's just the gaskets, that's easy to find and fix. If it's the porous block issue that's impossible to find on an inspection. Those lose more than a quart over 1K miles.

The manual will make it seem better, gearing is the fix no matter what on larger tires assuming it not a Sahara or a Rubicon as 3.21 is the base gear ratio. Sahara's usually came with 3.73's and the Rubicon usually came with 4.10's.
 
cranbiz said:
If it's just the gaskets, that's easy to find and fix. If it's the porous block issue that's impossible to find on an inspection. Those lose more than a quart over 1K miles.

The manual will make it seem better, gearing is the fix no matter what on larger tires assuming it not a Sahara or a Rubicon as 3.21 is the base gear ratio. Sahara's usually came with 3.73's and the Rubicon usually came with 4.10's.
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I guess that even a Sahara or Rubicon would want/need lower gears above a 33" tire?
 
paradisePWoffrd said:
I guess that even a Sahara or Rubicon would want/need lower gears above a 33" tire?
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Absolutely. I have a 2010 in my shop now on 35s. Had 3.73 and it was a total dog. Just pulling over the drain curb at my garage door it was struggling.
5.13 does wonders for them with 35s.
 
paradisePWoffrd said:
I guess that even a Sahara or Rubicon would want/need lower gears above a 33" tire?
Click to expand...
As Jody said, Yes. 4.10 with the stick is tolerable on 35's, barely.
3.8L gear chart.jpg
 
My 09 is an auto and the PO put in 4.56's and on 35's its still pretty underpowered on the highway. Wish he had installed lower gears, but the engine has been good other than it heating on me once and now it has a tick.
 
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