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Most reliable/unreliable engine


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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!

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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

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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?

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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.

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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.

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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

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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:

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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:

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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.

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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.

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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.

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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:

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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.

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