LobsterThief Posted June 22, 2011 Share Posted June 22, 2011 I'm still doing my research in preparation for buying an MJ shortly, so I thought I'd post this thread. Note: this will be my daily driver (no offroading), and I live in Florida (so no hills). In your opinion, what is the most reliable stock engine? In your opinion, what is the least reliable stock engine? Thanks! Link to comment Share on other sites More sharing options...
JeepcoMJ Posted June 22, 2011 Share Posted June 22, 2011 There all reliable. Only the 4.0 is worth messing with. Capable of the same mileage as a 2.5. The 2.8 v6 is reliable but capable of neither fuel mileage nor power. It is gutless. The 2.1 diesel is reliable, but only if you maintain it like a frenchman Link to comment Share on other sites More sharing options...
Automan2164 Posted June 22, 2011 Share Posted June 22, 2011 4.0 holds the tough and as anvil trophy in my book... 2.8 is the anchor. 2.1, while anemic and finnicky gets the unique award. Let the opinions flow. Rob Link to comment Share on other sites More sharing options...
LobsterThief Posted June 22, 2011 Author Share Posted June 22, 2011 There all reliable. Only the 4.0 is worth messing with. Capable of the same mileage as a 2.5. The 2.8 v6 is reliable but capable of neither fuel mileage nor power. It is gutless. The 2.1 diesel is reliable, but only if you maintain it like a frenchman Very helpful :) I've been looking into getting the 2.5 for fuel economy, but if I can get a 4.0 and get the same/similar mileage, that'd be great. Do you know which years had the 4.0? Link to comment Share on other sites More sharing options...
johnj92131 Posted June 22, 2011 Share Posted June 22, 2011 4.0 was from 87 to 92 Link to comment Share on other sites More sharing options...
LobsterThief Posted June 22, 2011 Author Share Posted June 22, 2011 4.0 was from 87 to 92 Awesome. Definitely going to get a 4.0. Thanks! Link to comment Share on other sites More sharing options...
FrankTheDog Posted June 22, 2011 Share Posted June 22, 2011 91-92 4.0 HO is probably the easiest to work on electrically. Never liked working on the Renix jeeps. Plus there is more XJ HO's on the road still to rob parts from then there are Renix era jeeps. :peek: Link to comment Share on other sites More sharing options...
dasbulliwagen Posted June 22, 2011 Share Posted June 22, 2011 If you find a nice 2.5, don't discount it. If you just want a DD, then it would probably be all you need. All the same body and suspension upgrades work for them just as they do for the 4.0, and they have the same reliability, just don't expect too much from the power dept, and youll be OK. Link to comment Share on other sites More sharing options...
zagscrawler Posted June 22, 2011 Share Posted June 22, 2011 I am a huge fan of the 4.0l myself. Ive got over 250000 miles on the original motor and even timing chain i believe. We have had the truck in the family since 16000 miles and it still runs strong. I tip my hat to this motor. :cheers: Link to comment Share on other sites More sharing options...
glundblad Posted June 23, 2011 Share Posted June 23, 2011 The value is in the 4.0. It has a reputation and is considered a desirable engine. You may find a 4 cyl in good shape for a great price. Then a few months later, a 4.0 comes up for the same money. Then you need to live with your self which in my case would not be easy. Link to comment Share on other sites More sharing options...
freakjeep93 Posted June 23, 2011 Share Posted June 23, 2011 i swear by the 2.5. my old truck was a 2.5 4 speed 2wd and could go everywhere a v8 4x4 chevy went. it always started and had enough power to spin 31s through some pretty thick mud and crawl up rocks. the same motor will eventually go into my new my if i ever get around to finishing it Link to comment Share on other sites More sharing options...
jeepsouth Posted June 23, 2011 Share Posted June 23, 2011 I vote for the 4.0! It is a tough engine,when I bought my mj I neglected to check the oil when I first looked at it. It was a 25 mi. drive home.Long story short it took three qts. to bring it up to level. It runs great idles great ,and gets around 20 mpg consistently. It has 169k on the clock.:cheers: Link to comment Share on other sites More sharing options...
Car RamRod Posted June 23, 2011 Share Posted June 23, 2011 I'm very happy with the mileage, power, and reliability of my renix 4.0. HO's are supposed to be a little easier to work with though. Link to comment Share on other sites More sharing options...
Jerry Posted June 23, 2011 Share Posted June 23, 2011 There all reliable. +1 :thumbsup: As for the 2.8L being gutless though. The 2.8L is always getting beat on! I have to jump in and defend the poor thing! :fs1: My blue one there in the pic has spent the last few years regulary hauling a fully loaded +1000lb camper up and down BC's mountains. It hasn't complained once! It just faultlessly got on with the job. Compared it side by side with the 4.0L and yes it may feel a little underpowered but it has a 1200cc disadvantage and carbs. It's got 160k miles on it, still runs like a sewing machine and uses no oil which is more than I can say for my 4.0L. Gas mileage is no better than a 4.0L so yes(!) if you have a choice get a 4.0L. But if you don't have a choice don't be put off if the truck you're looking at has the 2.8L V6 :thumbsup: Link to comment Share on other sites More sharing options...
jimoshel Posted June 23, 2011 Share Posted June 23, 2011 All 3 engines are good. I wouldn't buy or reject any Jeep based soley on the engine. I have MJ and XJ, and S10 daily drivers with all 3 engines and have no complaint with any of them. Yes, the 4.0 is more powerful and if you feel the need for more power then get it. The 2.5 will do everything the 4.0 will, altho in some extreme cases it might take a little longer. And the lowly 2.8. The most under rated engine for a Jeep and it doesn't deserve it. I have a 'MJ with the 2.8 and a 215K on the clock and it still runs like new, good mileage, sufficient power to do what ever I ask of it and very reliable. Just because one engine may place second when compared to another one doesn't make it a bad engine. Often times when statements are made about various engines, they are based on personal opinions and not facts. Link to comment Share on other sites More sharing options...
Car RamRod Posted June 23, 2011 Share Posted June 23, 2011 Gas mileage is no better than a 4.0L Really? I went from my mid-teen mpg 2.8 (if I drove easy, if I worked it, forget about it) to my renix 4.0 which easily sees upper teens mixed driving, and 20+ highway. Granted, the 2.8 had a 3 speed auto and the 4.0 has a 5 speed. Link to comment Share on other sites More sharing options...
Jerry Posted June 23, 2011 Share Posted June 23, 2011 Yup, really Maybe the manual box helps to the tune of 5mpg :dunno: Link to comment Share on other sites More sharing options...
Comanche County Posted June 25, 2011 Share Posted June 25, 2011 You buy the truck when its available and take whatever engine is in it. MJs were created by God for each of us, XJs were created so we could have a choice of engines to easily transplant into our MJs. :smart: Link to comment Share on other sites More sharing options...
Drahcir495 Posted June 25, 2011 Share Posted June 25, 2011 XJs were created so we could have a choice of engines to easily transplant into our MJs. :smart: :jump: Link to comment Share on other sites More sharing options...
grabber Posted June 26, 2011 Share Posted June 26, 2011 I bought a 89 4.0 new off the lot and sold it in 2000 with 185000, My boy bought the same one back 2 years ago after sitting 4 years in a field.. new battery, fresh gas and it ran.. still drives it, replaced a head gasket. 395000 miles and its a beast with power. Link to comment Share on other sites More sharing options...
banshee Posted June 26, 2011 Share Posted June 26, 2011 My renix had 214,000 when I rebuilt it 'or more to the point had it rebuilt' to a 4.7L still kicking... B... 91-92 4.0 HO is probably the easiest to work on electrically.Never liked working on the Renix jeeps. Plus there is more XJ HO's on the road still to rob parts from then there are Renix era jeeps. :peek: Link to comment Share on other sites More sharing options...
FrankTheDog Posted June 26, 2011 Share Posted June 26, 2011 My renix had 214,000 when I rebuilt it 'or more to the point had it rebuilt' to a 4.7L still kicking... B...91-92 4.0 HO is probably the easiest to work on electrically.Never liked working on the Renix jeeps. Plus there is more XJ HO's on the road still to rob parts from then there are Renix era jeeps. :peek: 350,000 miles on my 98 4.0 XJ, it's never been opened up. Still runs great. Link to comment Share on other sites More sharing options...
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