3.8 or 3.6

Utah_Jay

Utah_Jay

Member
The only time I am a bit disappointed with the power of the 3.8 is on extended trips on the freeway. For example driving what is normally 3.5 hours to Moab takes me over 4 hours in the JK. I just don't feel comfortable pushing it 75+mph with the 5.13's in it. Its sweet spot for me seems to be in the 65-70mph range. If you can live with that then the 3.8 is a great motor imo.
 
Peak

Peak

New member
I can easily go 80+ in a 3.8 with 5.13 gears with no issues. Even when towing I will unknowingly go 70-80mph while towing and I don't even realize it, no issues at all. Of course when I do realize I'm going that fast I slow it down a bit lol. I hardly burn oil too, still running 5/20 with 65K miles and maybe half a quart for me every 5k miles but I usually change my oil every 3K. I believe the only real issues with the 3.8s is the tranny those models come with.
 
Bustedback

Bustedback

Member
The 4.0 with 227k miles on it in my ZJ doesn't use a drop of oil, but it's also a gutless turd with 32's and stock gearing.
 
piginajeep

piginajeep

The Original Smartass
Bustedback said:
The 4.0 with 227k miles on it in my ZJ doesn't use a drop of oil, but it's also a gutless turd with 32's and stock gearing.
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My neighbor has a 90 MJ with 420,000 k on it. He says it still runs good !

I doubt you'll ever see a 3.6 with that many miles.
 
Spudcannons

Spudcannons

New member
One nice thing about the 3.6 is you can get a replacement for pretty cheap. I saw one for 2400 with 1200 miles on it.
 
JChamblee

JChamblee

New member
I have a '12 3.6 and have already had to have a head replaced. The valve seat o. The exhaust valve was completely gone, dealer didn't bat an eye and did completely under warranty. I bought this jeep with 40k miles and have put another 30k on it since. I love the pep and power, 3.73 gears and 35s doesn't get sluggish. However I miss my 4.0 302k miles and still pulling strong in my old XJ.
 
Jeep2010

Jeep2010

New member
I have a 2010 jk manual and I have put on 140,000 on mine, 35,000 of that being with 35'' tires and have had no problem. I've had to replace the exhaust manifold. That's about it. I don't like not having the power as much but I am planning on going with the cummins 4BT. But I work at a dealership and get to drive them and I'd prefer the 3.8 personally. But that's just me. Good luck.
 
jk12blk

jk12blk

New member
Is it a guarantee the head will fail on the 12' or 13' 3.6s? Are there any 3.6s with 50k+ miles where the head has not failed yet? Just curious. My jeep only has 12K and seems fine so far. I do hear a ticking noise when I first start it, but the sound quickly goes away.
 
mattfl

mattfl

New member
jk12blk said:
Is it a guarantee the head will fail on the 12' or 13' 3.6s? Are there any 3.6s with 50k+ miles where the head has not failed yet? Just curious. My jeep only has 12K and seems fine so far. I do hear a ticking noise when I first start it, but the sound quickly goes away.
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I had 56k on my '12 before I traded it in and the head hadn't failed. My friend has 53k on his '13 and the head hasn't failed.
 
Bustedback

Bustedback

Member
jk12blk said:
Is it a guarantee the head will fail on the 12' or 13' 3.6s? Are there any 3.6s with 50k+ miles where the head has not failed yet? Just curious. My jeep only has 12K and seems fine so far. I do hear a ticking noise when I first start it, but the sound quickly goes away.
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Chrysler says that about 7500 3.6 engines were effected with the head problems.
 
JKG33K

JKG33K

New member
Had #2 cylinder head fail at 11k on my 2012. Was replaced under warranty. Got 57k now and zero issues since...
 
JChamblee

JChamblee

New member
jk12blk said:
Is it a guarantee the head will fail on the 12' or 13' 3.6s? Are there any 3.6s with 50k+ miles where the head has not failed yet? Just curious. My jeep only has 12K and seems fine so far. I do hear a ticking noise when I first start it, but the sound quickly goes away.
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My 12 failed at 66k
 
mikefishes

mikefishes

New member
wayoflife said:
We put on well over 100,000 miles on Moby's old 3.8L and honestly, I don't think it burned hardly any oil at all. Like Tony, maybe half a quart every 3k. I love the extra HP the 3.6L puts out but so far, it doesn't seem to be lasting as long. As you know, we burn about a quart every 1,000 miles now but then, we do have almost 80,000 miles on the odometer and of course, Chrysler says this is normal :rolleyes2:
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Eddie,

I saw this while browsing the net earlier today. Then I saw your post here. Interesting.



http://www.consumerreports.org/cro/magazine/2015/06/excessive-oil-consumption/index.htm
 
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