my son is looking at a 1998 jeep cherokee, with a straight 6. it has 117,000km or 72,000 miles. I was wondering if anyone has any knowledge of theses vehicles. I was wondering how many miles theses motors are good for. anything to look out for when test driving it. thanks

 

I had the Jeep straight 6 in an 89 Cherokee and they are regarded as excellent engines. Mine is still going strong at 166,000 miles with only peripheral things replaced. If the former owner kept the oil changed it should be good. Pay close attention to the suspension. Take it up to 55-60 mph and make sure there is no shimmy in the steering wheel. Put it in 4WD and make sure your run it in both forward and reverse in all ranges. Check the paint for signs of peeling clearcoat from sun damage. The manual says it is good for towing to 5000 pounds but dont believe it. These things hate to tow and their short wheelbase is poorly suited for it. Check to se if the overdrive lockout button works. Good luck

 

I had a '90 with the inline 6. Those are easily 250k mile motors, quite hardy if reasonably maintained. Mine had 93k mi. when I got it, and 185k when I sold it, and it still ran great, though it needed a clutch by then. I'd be sure to get the 4wd stuff checked out, especially if it has the vacuum operated front hubs.

My only gripe with the 4.0 is the so-so mileage. I thought I'd get better than 18mpg in such a light setup. Could've been because I enjoyed the zip the thing had.

Some of the externals go at the usual intervals. I replaced my starter motor, radiator, battery cables, and timing chain and gears. I think that's the biggest thing to expect, every 80-100k miles or so, the timing stuff. Not a hard job, and I'm no great mechanic either. They did however shoehorn that 6 into there pretty tight, so eyeball that to see if you'd like working in that space.

I miss my jeep. Sold it because it couldn't haul two horses after I got married.

 

I will agree with what has already been said. My daily driver is a 92 xj with the 4.0. I bought it with 160,000 miles and now it has 185,000 miles on it. all major components are still factory original. I get 20 mpg on the highway taking it easy in OD. 5 speed manual tranny.

 

My wife has a '96 with the 4.0 and auto trans - it's a dandy engine as already said. She gets low 20's mpg, but when I drive it the mileage drops to around 20. Odometer is up around 188,000.

My only complaint has to do with the plastic parts on the interior of the vehicle where metal fasteners should have been used. Otherwise it's pretty decent for a 10 yr old rig that isn't babied....its my wife's 'truck'.

 

We are on our second Jeep now, both were/are equipped with the 4.0. The American Motors/Chrysler 4.0L is IMO, one of the best engines ever produced.

Here's another good thread with more opinions:

LINK

 

I have very little experience with these, but my former boss and I discovered that the transfer case on these Jeeps REQUIRES 12K mile oil changes. If you forget to change the transfer case oil, you get expensive damage if you go long enough. His was a late 90s or 2000 model with the straight 6. I think his case went at something like 50K miles or so and required bearings etc. We discovered the problem in the middle of the dessert(Tricities to Portland) when we had a lot of road rumble. I thought the tire had thrown a weight and we were out of balance. It was the case.

Most people don't think of tranfer case oil changes, I think my F250 sayd at 100K. SO I bet more than a few of these Jeeps have dirty fluid or damage.

So check the maintenance history and if you hear any unusal rumble or howl from the tranny area, beware.

Jim Henderson

 

My 98 cherokee sport I bought at 43k and now has 82k required maintenance, shocks and water pump. And it is still a strong runner( 24 mpg highway-19 mpg city) not bad!

 

If you change the oil every 3k, then both the I-6 258 and 4.0 are motors that will go 200,000-300,000 miles without a rebuild. Next to the slant six, they are some of the best built motors to ever come out of that company/AMC.

The real weak point of any Jeep has been its electrical system. Really does not matter what year or model. Make sure it starts correctly in all gears and if it is 4x4 that it works correctly. The switch on the transmission can not be easily rebuilt and is $300 to replace

It is OBD II, make sure you bring it some place and have them run a scan. Some vehicle owners have been known to disable the lamps to mask a problem.

Make sure it does not leak from the tranny and the fluid has been changed at least once. If you buy it, change the fluid right away. If it requires ATF3, make sure some moron does not use Dex3.

 

I recently sold my 88 jeep. I got it with 224,000km on it. Had bad blowby, but ran good. Made a catch jar for the blowby, for it plugged the air filter real quick.
I got around 18 per gallon on it. It did not smoke and had 100psi in cyl. It was close to needing a rebuild.
I found from talking on a jeep site that most of thes e engines developed blowby around 200,000km The guides are the culpret. Otherwise they keept going.
Reason I got rid of it was I'm a large man and getting into it and sitting in it was cramped for me and not comfortable. More comfortable driving my ford truck and having room.

 

Lets see, in my drive right now is three 4.0l motors, one with 160k miles, one with 189k miles, and one with 260k miles, The one with 289k miles is at my shop with the bed full of stuff. Basic preventative maintence, and some TLC is what they require.

And use the lubricants that Jeep recommends for the T-cases and transmissions and diffs. That changed depending on the year.

Ooh, and Jeeps don't leak oil, they mark their territory.


Wow, I killed the linked thread, lets see if I manage to kill this one too.

 

150,000 miles is half life of a good mantained 4.0, the only other motor this good, would be the ford 300 I-6. I mean in lowend grunt, and longevity. The jeep 4.0 was an awesome motor, and will be missed in the jeep family. The end of the 4.0, and 2.5 brought to a close the end of an aira, of cam in block, inline engines.