jk motor and kj motor

XR · **Posted:** Wed Dec 24, 2008 5:55 pm

I like my 3.7 OHC.140K and no issues.Works for me on the street and trails.Wait until it wears out and I can do some headwork,pistons and cams.

InCommando · **Posted:** Fri Dec 26, 2008 10:59 pm

On the I6 4.0 at 140k, you would have had to replace an exhaust manifold or two, had some bolts back out*, leaked a bunch of oil, and had a CPS go out once or twice.... :shock:

It is no better or worse than most engines of its era in this regard, but it does not walk on automotive water, either.

*Several "blown up" 4.0's have been replaced when the flex plate bolts backed out, causing them to hit the block & creating a "knock" that sounded like a spun bearing knocking. Some people know to look for this, some do not.

Sir Sam · **Posted:** Sat Dec 27, 2008 1:14 am

InCommando wrote:

On the I6 4.0 at 140k, you would have had to replace an exhaust manifold or two, had some bolts back out*, leaked a bunch of oil, and had a CPS go out once or twice.... :shock:

It is no better or worse than most engines of its era in this regard, but it does not walk on automotive water, either.

*Several "blown up" 4.0's have been replaced when the flex plate bolts backed out, causing them to hit the block & creating a "knock" that sounded like a spun bearing knocking. Some people know to look for this, some do not.

This is not my experience at all. I think your view of the 4.0 is very jaded. You go out of your way to speak ill of the 4.0 whenever you get the chance.

InCommando · **Posted:** Sat Dec 27, 2008 4:08 pm

If you are unaware of the exhaust manifold issues on the 4.0 I6, there are numerous numerous numerous sources to check it out and educate yourself about them. Just as one quick example I can recall off of the top of my head, look at the 12/08 issue of JP magazine. It is a periodical for jeep enthusiasts.

The crank positioning sensor failure is so common that it is about the first thing you check if your 4.0 I6 Jeep won't start. Again, there are countless posts and articles about this problem.

I have just heard the 3.7 bashed across the 'net in favor of the 4.0 I6 without any facts. Can you provide verifiable dyno charts for comparision? I have found that the 3.7 posts 185 #'s at a low 1,200 rpms, and that the 3.7 has more max tq at the same RPM while having more HP, as well. But no one has shown anything to support their 4.0 I6 claims.

"It is no better or worse than most engines of its era in this regard, but it does not walk on automotive water, either." Maybe you read over that? :roll:

How "ill" is that statement? Granted, I do not pray at the 4.0 I6 alter. Maybe my realistic view appears negative because of that? Or maybe because I drive a stick and many more TJ's with the 4.0 I6 were sticks while KJ's are largely auto means that I can make a more apples-to-apples comparison than some others? An auto with a stock converter definitely acts differently at low RPM's than a stick. You have to overcome the stall and the uninformed will see that as not making any low RPM power when in fact it is just wasting power until the convertor stops slipping.

Sir Sam · **Posted:** Sat Dec 27, 2008 7:53 pm

InCommando wrote:

If you are unaware of the exhaust manifold issues on the 4.0 I6, there are numerous numerous numerous sources to check it out and educate yourself about them. Just as one quick example I can recall off of the top of my head, look at the 12/08 issue of JP magazine. It is a periodical for jeep enthusiasts.

The crank positioning sensor failure is so common that it is about the first thing you check if your 4.0 I6 Jeep won't start. Again, there are countless posts and articles about this problem.

I am not speaking to those issue, I find any such discussion of the 4L out of context, I rarely see the need for the discussion to compare it to the KJ.

Yet when the topic does come up rather than speak to a rounded holistic view of the apples and oranges comparison, you speak with a rather one sided view.

I'm sorry, I just don't understand why you seem to want to "educate" in your own way whenever you get the chance to slip it in.

InCommando · **Posted:** Sat Dec 27, 2008 8:09 pm

And what are you doing with these posts that actually have nothing to do with the 3.7, 3.8, or 4.0 I6 but allow you to make your completely out of context jabs without being anywhere in the same area code with "on topic ?" It is quite obvious that you are not "speaking to those issues" as they have something to do with the topic and that is not your purpose at all. Glass houses, and all of that.

Maybe being educated would keep someone who claims "experience" from embarrassing themselves by being ignorant of even very common failings of the 4.0L I6.

If you have issues with another poster but are afraid to go after them ( or cannot compete with them), do not resort to attacking said poster's buddies.

Knowledgeable - But Caustic You have shown the Caustic repeteadly here but I have yet to see the other side.

Begone, Troll. Come back when you are out of school and perhaps have some actual "experience."

Diggerfreek · **Posted:** Sat Dec 27, 2008 8:38 pm

alright every one, lets keep it cool

Burchie · **Posted:** Sat Dec 27, 2008 9:41 pm

Diggerfreek wrote:

alright every one, lets keep it cool

Guest · **Posted:** Sat Dec 27, 2008 9:42 pm

InCommando wrote:

look at the 12/08 issue of JP magazine. It is a periodical for jeep enthusiasts.

If you don't mind my inquiry, good sir, what sort of periodical is this? Annual? Biannual? Would you say it is a reputable publication?

ThunderbirdJunkie would enjoy such a form of printed entertainment, and the whereabouts would be greatly appreciated.

In all seriousness...

LOL

ThunderbirdJunkie honestly believes the 4.0 vs 3.7 argument is valid in this thread, because of the "new" vs "old" discussion already brought on in the topic. If one does not see the similarities, he would like to invite that person to go to their local proctologist for a rectal craniectomy.

InCommando · **Posted:** Sat Dec 27, 2008 9:51 pm

Diggerfreek & Burchie, you have my word that I will keep this about engines if the young PADawan does so. Looking at this shows clearly who came gunning for who.

I really am not knocking the 4.0 I6 as much as pointing out that its rep may be more hype than history. I do not see anyone being very eager to swap their SBC's or Hemi's for 4.0 I6's, but I have read of or seen hundreds of swaps in the reverse.

The KJ is somewhat heavier than either an XJ or a TJ. I think that some fail to realize this when evaluating the differences, either. But no matter how you slice it, the 4.0 I6 is a step backwards from the 3.7 or 3.8 in many ways. Even if it does offer better torque for a couple of hundred RPM's ( a claim no one has stepped forward to prove), the other advantages of the more modern engines are clear.

Sir Sam · **Posted:** Sat Dec 27, 2008 11:08 pm

InCommando wrote:

It is quite obvious that you are not "speaking to those issues" as they have something to do with the topic and that is not your purpose at all. Glass houses, and all of that.

No, I am not speaking to those because I don't care to debate the merits of the 4L with you. This thread is not the place for that discussion.

InCommando wrote:

Maybe being educated would keep someone who claims "experience" from embarrassing themselves by being ignorant of even very common failings of the 4.0L I6.

Don't confuse my silence with ignorance, I suspect I have a great deal more knowledge about the 4L/XJ than you think.

InCommando wrote:

If you have issues with another poster but are afraid to go after them ( or cannot compete with them), do not resort to attacking said poster's buddies.

I'm hoping your not talking about me, because I have no idea what your talking about here.
(though I would surmise that you think I have attacked one of your buddies in lieu of attacking you, even though I do not know who you are, or who your buddies are)

InCommando wrote:

Knowledgeable - But Caustic You have shown the Caustic repeteadly here but I have yet to see the other side.

Begone, Troll. Come back when you are out of school and perhaps have some actual "experience."

InCommando wrote:

Diggerfeak & Burchie, you have my word that I will keep this about engines if the young PADawan does so. Looking at this shows clearly who came gunning for who.

Once again I have kept a civil tone, and you have not. In the past your grinding attacks finally got to me and I dropped to a less than civil level with you. I apologize for that and will try not to let less than civil discussion get to me.

InCommando · **Posted:** Sat Dec 27, 2008 11:45 pm

The predictability is strong in this one.

Where, oh Student, would one discuss the merits of engines if not in a thread regarding the merits of engines? That is a rhetorical question as the answer is obvious to everyone. Well, almost everyone......

Tokyojoe · **Posted:** Sun Dec 28, 2008 12:41 pm

There is a difference between discussing and attacking.

Plain and simple

1300ZUK · **Posted:** Fri Jan 02, 2009 9:31 pm

jeepkj02 wrote:

InCommando wrote:

Funny, I do not recall the NSG370 being available in the minivan???? :shock:

I don't think any minivan (from any mfg) came with a stick. Don't think soccer moms know how to drive a manual. HAHAHA!! :lol:

where to you want me to start?

Dodge Caravan?
Chevy Astro?
Toyota Previa?

:lol:

DarbyWalters · **Posted:** Fri Jan 02, 2009 9:47 pm

I am just dissappointed that they took a 3.8L V6 at 202hp...when the 3.7L V6 already had 210hp and the H3 I5 has more than both. Jeep should have stepped it up with something around 260hp IMO in a 4500# vehicle.

tommudd · **Posted:** Fri Jan 02, 2009 9:53 pm

DarbyWalters wrote:

I am just dissappointed that they took a 3.8L V6 at 202hp...when the 3.7L V6 already had 210hp and the H3 I5 has more than both. Jeep should have stepped it up with something around 260hp IMO in a 4500# vehicle.

I agree I was going over some specs last night and knew the 3.8 had only 202 but when I saw it again I stopped and thought what the heck were they thinking, 260/275 HP would of gave decent mileage and power all around

tjkj2002 · **Posted:** Fri Jan 02, 2009 10:50 pm

Just get over it,the 4.0 I-6 is gone.Personally I'd rather have the Ford's 4.9 I-6 over the 4.0 I-6 anyday.

InCommando · **Posted:** Sat Jan 03, 2009 9:46 pm

If they wanted to save $$$ and use an already available engine, the 4.7L V8 should have been the base engine in the JK, IMHO. Other than that, the 4.0L V6 hits the HP #'s Tom is mentioning.

dieselenthusiast · **Posted:** Sat Jan 03, 2009 10:38 pm

Now this is the motor that should be in the JK......................

Todd and www.dieseltoyz.com made a trip to Germany and took several photos for me. I'm swapping a European CRD into a 2007 4-door JK.

1300ZUK · **Posted:** Sun Jan 04, 2009 12:11 pm

There are a lot of engines that Chrysler could have put in it.

But they are extremely poor and have very limited Research and Development money and equipment. Its amazing the cars at the end of the line even start.

and my guess is JK's get the 3.8 because it was cheap, had enough capacity to build them, proved more fuel efficient in testing, and didn't have enough power to break other parts (reducing warranty costs)

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