4.0l vs 5.2l

[petrolclock]

kinda stuck here
i really love the 4.0l cause there soo easy to work on and a proven engine but i seen a 97 zj5.2l with only 63k miles for sale thats why i am asking this question.
whats the better engine for a expo build zj with mods being 31's, full skids, maybe a bullbar and winch, plus gear for camping and what not.
i hear people saying the 4.0l is under powered in a grand but i take that with a grain of salt. people say the kj is underpowered but the 3.7l is good enough for me.
main concerns are
-reliability
-fuel eco (seems like the 5.2l only gets 1mpg less then the 4.0l well thats what people say anyway)
-zj with 4.0l with the mods mention able to push its self up mountain roads without downshifting to 2 lol
- v8 over heating on the trail?
what would you perfer if you had a choice?

 

[JakeC]

The 4.0 and the 5.2 are both great engines, and last a long time if maintained. My 5.2 has 199,XXX miles on it and still runs great. The mpg's are minimally different. Some people say that you need to re-gear if you plan on running bigger tires (33's+) with the 4.0. Most 5.2's also came with the Dana 44a rear axle.

One thing to look into is that most 5.2 engines in the ZJ came with the Limited Edition Grand Cherokees, meaning that they had AWD and the NP249 transfer case. This transfer case is known to have problems with the viscous coupler that will cause your tires to skip on pavement and the transfer case to bind when in full lock after it comes to operating temperatures. To combat this, people will swap in an NP242 (Selec-Trac) or an NP231 (Command-Trac) from Cherokees or some Grand Cherokees.

I personally enjoy that I have the 5.2. It's got the power that I like when I want to really slam on the gas pedal and pass someone and it's been a great engine since I've owned my Jeep. I've never driven a 4.0 but other forums I frequent have had this debate countless times. There are some hardcore 5.2 and 4.0 fans around!

I think the engines are pretty much equal, and either would be a great choice for an expo vehicle. But my opinion is bias, even though I'd jump on a 4.0 if I had the money and the opportunity.

 

[BlueBomber]

A 3.7 in a KJ is probably ok, but a ZJ is a a little big for the 4.0. I have one with the 4.0 and a 249 transfer case and it is SLOW. If you're ok with slowing down and taking in the sights, then a 4.0 might be ok for you. But I would look for one with a V8 if I was going to buy another ZJ.
-reliability----about the same as any engine, take good care of it and it won't let you down.

-fuel eco----no real diffrence

- v8 over heating on the trail?----if you get a ZJ (V8 or I6) I would look at what others have done to vent the heat from under the hood. It seems to me (that means this is my opinion) that the ZJs have some trouble getting enough air past the radiator to keep cool at low speeds. My jeep does just fine but most of the cooling system is less than two years old. I think some vents in the hood or fenders would be good insurance against overheating when offroading.......or sitting in traffic.

 

[tatuedrednek]

I run an xj with a 4.0 and believe you me on the highway it is a weiner! I'm running 31s and 3.55 gears. A Grand is whole lot more vehicle. On the trail the little six cylinder is awesome just because of the torque that comes with running an inline engine. I've never had any cooling/overheating issues with mine. Going to a lower gear in my diff would help on the highway, but in my opinion slowing down and taking in the sites is what lifes all about! As far a mpg goes, I've never been concerned from the economic stand point, although I would like a larger fuel tank for any range issues that I may encounter. I know my little xj is a thirsty bugger on the highway, but does much better on the trail. Only other advice I have if you're looking into a 4.0 is make sure you have a spare crank sensor in your tool kit. That is the main fail point of those little engines, and for 50 bucks, it's cheap insurance!

 

[just jose]

petrolclock,

I have owned a '95 GC Laredo with the 5.2L V8. One item to look for is signs of head gasket failure. Look under the oil filler cap for the white milky build up. Although my GC ran great, it did use water and keeping an eye on the cooling system was part of the routine. It never overheated, but it did get hot while running A/C and running up and down dirt trails or street driving on hot summer days. It did get very hot under the hood and I had plans on installing vents on the hood like the '98 5.9L GC has. Also, the 5.9L GC came with two electric cooling fans, vs. the standard clutch fan.

With the 5.3L engine, down shifting to low on the transfer case is seldom needed. My very best highway gas milage was 17mpg. The worst was 12mpg during a hot summer heat wave and driving in city traffic with the A/C blasting.

From what I have read from other GC owners with 4.0L engines, is that the vehicle is under powered due to the GC's weight.

If you do plan on purchasing the GC, one improvement that I would suggest. Would be to install Bilstein shocks on it. It made a huge difference from the standard shocks. Unless, the GC you are looking at has the High Country package, then the Bilsteins are part of that package.

Good luck, hope this info helps,

Jose

 

[Recce01]

I have actually owned both, still own a V8 version. The major difference is the power pulling hills. Both of my ZJs were lifted, my 98 5.2L on 32's gets 14mpg HWY, my 93 4.0L on 31's got 14mpg as well. I have experienced overheating in my V8, but that was climbing steep grades while towing, so far no issues on the trail "Knock on wood". The V8 grands also have an aluminum center section Dana 44 which some seem to complain about, although those complainers were demanding much more than your average overland route from their Jeeps. My Grand V8 has 217K miles on it, and I love it!

 

[petrolclock]

thanks for the replies fellas
like i said before only reason am asking the questions is because i found a v8 zj with only 63k miles !!!! its just kinda hard to pass up with that ow of mileage even though i want a 4.0l.

 

[Recce01]

what's the asking price? I am looking for a low milage motor, JIC of course

 

[petrolclock]

found another one
a 95 with 107k 5.2l for 2600
the 97 with 63k miles they want 7k for it
ummm is paying alot more worth having the lower miles?

 

[K2ZJ]

Is 44k worth $4,900?

 

[HillbillyfromAL]

If it were me and I wanted more power a stroker would be what I'd go with if it's ever a trail Jeep. There may not be big differences in fuel economy on road but I've found that V8's like a lot of juice in low range. You can't really beat the torque delivery of the 4.0 unless you swap in a diesel off road. JMHO

 

[JakeC]

Is 44k worth $4,900?

Especially if you can find one with 107K for $2600 before haggling. My girlfriend's father originally bought mine for $2600 with 18X,XXX miles and I bought it from him for $2300. But mine was garage kept, and living in a place like Indiana, i'm thankful for it after seeing the underside of some other ZJ's.