4.0L engine rant...

[loves_off_roading]

I recently bought a Jeep Cherokee with a 4.0 engine. Nothing against the 3.7, but this thing is the shit. I love the torque!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

I've heard from a lot of sources that this engine can go over 300,000 miles without rebuilding. Mine has 170k and still runs strong. But yet Chrysler discontinued it in 2006. I just don't understand this. Why? It might not be great for a Liberty (since the Liberty is so heavy). But they could of at least kept it in the Wrangler. Why put a crappy minivan engine in a wrangler?????

Just upset that Chrysler discontinued one of the best engines of all time for modern so so.

 

[Marlon_JB2]

Emissions.

It couldn't pass emissions standards, and by the time they put the engineering money into the 4.0L, they could have made an entirely new engine... but why do that when you have the 3.7L on the shelf left over by AMC? (Yes, the 3.7L/4.7L is a leftover from AMC, but not many are actually aware of that, the 4.7L was originally supposed to be released with the ZJ but Chrysler management already had a V8, the 5.2L Magnum which they already dumped a ton of money into...)

Plus to top it all off.....

Crash Standards mandated by the US Government, and likely, other agencies.

In other words, it was a several decades old engine, and it was time for it to go bye-bye. That is why the 4.0L is no longer produced. It was time to move on, and even its replacements, the 3.7L and 3.8L are dead!

 

[loves_off_roading]

dang government!!!!!!!!!!

I never knew that the 3.7 was designed by AMC. Nice

hey Marlon nice Liberty man

 

[Marlon_JB2]

Well the original design was 100% AMC.

Chrysler finished it off, some years later.

And thanks!

 

[Marlon_JB2]

For those who do not understand the process in which vehicles and engines are developed...

This isn't an overnight process. Take the KJ for example.

Styling and development on it was started in 1996, RIGHT AFTER the release of the refreshed XJ Cherokee. It wasn't released until 2001 for the 2002 model year. So by 1997, it was over, it was what it was to be.

The platform started evolving in 2002 when the KJ Liberty was released, to become the KK Liberty.

So really, what you see JUST RELEASED ON THE ROADS, was an idea which already existed 5-6 years PRIOR.

 

[tjkj2002]

The 4slow is really not a good engine,constantly leaks oil from the same spots no matter what(valve cover,oil pan,rear main,oil filter adapter o-ring).Can't keep the exhaust manifold from cracking either and has freeze plug issues if you do not keep fresh coolant in it.The XJ's cooling system is a joke also.

 

[J-Thompson]

Funny
I have a 10 year old 4.0 that gets abused
It has seen the revlimiter more than a few times
which is said to be the cause of the rear main
leak ,I have NO drips
It also makes torque where I want it ,way way low RPM
which the newer engines do not do

 

[seabass1858]

I sold my trail rig 95xj, 4.0l, Aw4, np231 with tera 4:1 low and a wide chain kit, 4.5in RE lift, 33x10.5 bfg, xjD44, D30 with e-lockers, skid plates, 310K miles no smoke and replaced rear main at 250k. sold for $4100 and the guy pulled the motor and gave it back to me only to put a Cummins 4Bt in it.

 

[Ry' N Jen]

I know a few folks with Cherokee's with the four litre straight six with well over 350,000.0 miles on the original engine.
So they leak some oil, big deal!
Our KJ's valve cover gasket leaks...
Does that make it a ****** engine?

 

[seabass1858]

Babalooba's 02 4x4 kj 3.7 has 332k original miles on it all original drive line and no issues except for the valve-cover gaskets. All he ever bought was 2 radiators 6 sets of tires, too much oil to count, 14 ****** fluid services and some weatherstripping all the way around because of canadas harsh winters.

 

[NastyKnate]

im a fan of the 4.0 straight 6. its one of the most reliable engines out there. but its was low on power for its size, weak mpg, and it was dirty.

i just did 300000km on the 3.9 magnum v6 in a ram. it had torque, never had an issue, reliable as all hell. but it was also low in power for its size, dirty and got weak mpg.

ive got the 3.7 now. and i like it. it has more than enough power for me, more hp and torque than the 3.9 and gets me about 8mpg more.

its got 125000 on it so far. ie only had it 6months. i plan on doing another 150000km with it.

as for the comment about a minivan engine? the new pentastar is a fantastic motor. it keeps getting smaller and producing more power./better mpg. i was happy to see it squeezed into jeeps.

you want to get angry? google 2014 liberty

 

[04Liberty]

The old I-6 Jeep engine is one of those much loved classic indestructible engines (much like the slant 6 Chrysler). Unfortunately both of those engines fell victim to getting obsolete/not being able to meet emissions standards.

 

[tjkj2002]

Funny
I have a 10 year old 4.0 that gets abused
It has seen the revlimiter more than a few times
which is said to be the cause of the rear main
leak ,I have NO drips
It also makes torque where I want it ,way way low RPM
which the newer engines do not do

I sold my trail rig 95xj, 4.0l, Aw4, np231 with tera 4:1 low and a wide chain kit, 4.5in RE lift, 33x10.5 bfg, xjD44, D30 with e-lockers, skid plates, 310K miles no smoke and replaced rear main at 250k. sold for $4100 and the guy pulled the motor and gave it back to me only to put a Cummins 4Bt in it.

In the last 18 months I've sent 24 vehicles to the junkyards with "beyond repairable" internal engine damage,20 of them have been the 4slow and all have had less then 150k on them.The engines don't last without oil in them.The other 4 were all honda 2.4's.

Getting 200k is not hard to do on any engine built in the last 10-15 years unless it's the 2.8 CRD.As soon as I see a all original 4slow reach over 700,000 miles then I may consider them somewhat good.

 

[seabass1858]

A little off topic but I know of a few SBC 305/350 that have over 700k on them. They are in my dads fleet (G20/G30, silverado work vehicles), the 1991 of his has a 700r4/np205 never replaced or rebuilt, just fluid and filter changes and totes 2k in supplies frequently in a utility trailer, it has 758k miles the exterior is in good shape but the interior turns stomachs instead of heads.

 

[jschenck]

I've heard a lot of good things about the 4.0, but I've seen some really crappy ones too. Any motor from any car maker will have problems if it's not properly maintained. Period. Will some engine platforms generally last longer and perform better than others? Absolutely! But even within one engine platform the reliability of an engine can very greatly! Not that I don't have my own favorites, because I do. But, arguing what motor is the best can be pointless because opinions are like *****, everyone has one and a lot of them stink. I personally think the GM 3800 Series II engine (particularly the L67) is one of the best motors ever made, but I love the 3.7 in my liberty. I loved the 5.0 in my 84 F-150 as well. All some of the better motors from the respective car company, IMHO. But, each of you can blast everyone of those engines for various things. So what?

 

[lautinjr]

I've heard a lot of good things about the 4.0, but I've seen some really crappy ones too. Any motor from any car maker will have problems if it's not properly maintained. Period. Will some engine platforms generally last longer and perform better than others? Absolutely! But even within one engine platform the reliability of an engine can very greatly! Not that I don't have my own favorites, because I do. But, arguing what motor is the best can be pointless because opinions are like *****, everyone has one and a lot of them stink. I personally think the GM 3800 Series II engine (particularly the L67) is one of the best motors ever made, but I love the 3.7 in my liberty. I loved the 5.0 in my 84 F-150 as well. All some of the better motors from the respective car company, IMHO. But, each of you can blast everyone of those engines for various things. So what?

agreed the 3.8 was great, and Ive had no issues with the 3.7 in the Jeep. over 100k no oil leaks not even valve cover leaks. doesn't lose a drop over oil changes. The engine seems to have great HP and torque. 4slow was a good motor just out dated. As I understand it the 3.7L is a Mitsubishi motor not AMC even tearing it down on other Jeeps it always looked more import. Is there any documentation you could link to the AMC info you have I would really like to read it. Mitsubishi makes World Class Motors and Dodge has been known to use them for years are multiple vehicles so it made cents. Specially after pulling the plugs and seeing NGK V-power like every other Mitsu in the Dodge Chrysler line up.

 

[tjkj2002]

agreed the 3.8 was great, and Ive had no issues with the 3.7 in the Jeep. over 100k no oil leaks not even valve cover leaks. doesn't lose a drop over oil changes. The engine seems to have great HP and torque. 4slow was a good motor just out dated. As I understand it the 3.7L is a Mitsubishi motor not AMC even tearing it down on other Jeeps it always looked more import. Is there any documentation you could link to the AMC info you have I would really like to read it. Mitsubishi makes World Class Motors and Dodge has been known to use them for years are multiple vehicles so it made cents. Specially after pulling the plugs and seeing NGK V-power like every other Mitsu in the Dodge Chrysler line up.

The engine was reportedly designed as a replacement for the 4-liter AMC I-6, with the 3.7 to replace the AMC 2.5. According to Bob Sheaves, the concept originated at AMC, before the company joined Chrysler

Next generation V8 engine - the Dodge/Jeep 4.7 liter V-8

 

[dude1116]

agreed the 3.8 was great, and Ive had no issues with the 3.7 in the Jeep. over 100k no oil leaks not even valve cover leaks. doesn't lose a drop over oil changes. The engine seems to have great HP and torque. 4slow was a good motor just out dated. As I understand it the 3.7L is a Mitsubishi motor not AMC even tearing it down on other Jeeps it always looked more import. Is there any documentation you could link to the AMC info you have I would really like to read it. Mitsubishi makes World Class Motors and Dodge has been known to use them for years are multiple vehicles so it made cents. Specially after pulling the plugs and seeing NGK V-power like every other Mitsu in the Dodge Chrysler line up.

The only thing I've ever seen Mitsu motors do is seize. Like the 4 ****** in the old Dodge Stratuses and the 6 cyl in the Eclipses. World class my ass. -__-

 

[lautinjr]

thanks good read. Agreed always laughed at the world class thing. Build a valve seal that works then start thinking ahead .

 

[loves_off_roading]

tjkj2002 I'm sorry but how can you say that 4.0l engine is bad because it leaks oil?? We all know that. It's not a big deal. That's why you check your oil level. It has a trac record of going over 300,000 miles. You can't denie this. It's a good engine period.

As for the 4slow... I have a friend at work who says he beat out a sports car with a 4.0 Comanche

Any response to that?