Nthaworx Posted December 13, 2015 Share Posted December 13, 2015 Hey guys/gals. I'm new to the Mj world have owned plenty of 4.0 Xj's. My question is how reliable or unreliable are the 4cyl motors?? I'm looking for an Mj locally and most I've came across are all 4cyl. Would it be worth buying? Or wait to find a 4.0 Link to comment Share on other sites More sharing options...
87Warrior Posted December 13, 2015 Share Posted December 13, 2015 2.5 is just as reliable as the 4.0! Do not turn down a nice MJ because it has the 2.5. If you don't happen to love the 2.5, a 4.0 swap isn't very difficult and is well documented. My 86 2.5l truck is quite a trustworthy rig. It did just as well as my 4.0 TJ and and an XJ have powering over mountain passes in Colorado. The 2.5 obviously won't have the same grunt as a 4.0, but it still does great and is totally worth exploring as a power plant. Here is my 185k mile 2.5 on Black Bear Pass. Link to comment Share on other sites More sharing options...
Nthaworx Posted December 13, 2015 Author Share Posted December 13, 2015 Awesome! I just wasn't sure! I appreciate the input. That makes me more willing to buy it!! Link to comment Share on other sites More sharing options...
Minuit Posted December 13, 2015 Share Posted December 13, 2015 The 2.5 will do anything you need to do, it just won't be as much fun or get you there as quick as the 4.0. It was actually one of the more powerful 4 cylinder truck engines in its day, so it's better than most in that respect. Just imagine a 4.0 with 2 cylinders chopped off. That's exactly what it is. Link to comment Share on other sites More sharing options...
dasbulliwagen Posted December 14, 2015 Share Posted December 14, 2015 www.4bangerjp.com has lots of info specific to the 2.5. They deal mostly with the port injected models of 91 on up, but the base longblock is the same. I don't go off road, but mine does all I ask of it. Ive gutted and sleeved the cat, removed the engine driven fan and installed a controlled electric one, added a "cold " air intake. It has pepped up a little but you still have to remember you only have a 4 cyl. I have a stainless header and Mopar stage 3 cam to put into a 2.5 rebuild in the future as well. And like was said, its an (relatively) easy swap out for the 4.0 if you want that in the future. Link to comment Share on other sites More sharing options...
outlaw star Posted December 16, 2015 Share Posted December 16, 2015 Great little engine. Just rebuilt mine as well. I don't need speed anymore. Lol Link to comment Share on other sites More sharing options...
Darren Posted December 16, 2015 Share Posted December 16, 2015 Don't buy a 4-banger MJ. There isn't much (if any) difference in price between 4 and 6 cylinder trucks. The 4.0 makes more power yielding similar fuel economy, so why buy a four banger? Never buy a 4 cylinder thinking you may swap in the 4.0 later. It's not worth the time or money when you could have bought one to begin with Link to comment Share on other sites More sharing options...
shelbyluvv Posted December 16, 2015 Share Posted December 16, 2015 Welcome back Darren. Link to comment Share on other sites More sharing options...
Darren Posted December 16, 2015 Share Posted December 16, 2015 Thanks Bo. Link to comment Share on other sites More sharing options...
mvusse Posted December 17, 2015 Share Posted December 17, 2015 Similar Mileage? I get 27 mpg highway, 21 mixed in my 4 cylinder. Best I ever got out of a 4.0 was 24 highway, 17 mixed. 21 mpg is a 24% improvement over 17. Link to comment Share on other sites More sharing options...
benjy_26 Posted December 26, 2015 Share Posted December 26, 2015 I've put in a bit over 35,000 miles of city, highway, and off road driving in the almost 2 years since I got my MJ. I got mine with 190,000 miles on the clock, and aside from maintenance and Cruiser's Renix tips (and a new exhaust system) I haven't had to do anything to the engine. It's dead-nuts reliable and gets me over Southern NM and West Texas mountain passes pretty well, even when pushing around 31's with a 3.55 geared rear end and an AX4. It's not the fastest truck, but it's gotten me everywhere I needed to be and has done it getting at least 25mpg on the highway. Link to comment Share on other sites More sharing options...
outlaw star Posted December 28, 2015 Share Posted December 28, 2015 Remember, you bought a Jeep, not a Ferrari. Its meant to drive and enjoy the cruise, not win any races. Link to comment Share on other sites More sharing options...
64 Cheyenne Posted December 28, 2015 Share Posted December 28, 2015 If I had to make a choice between a nice MJ with a 4cyl and a rusted pos hulk with 4.0, well let me just say there wouldn't even be an issue, 4cyl and nice beats rusty pos 4.0 any day.... Link to comment Share on other sites More sharing options...
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