Reliability of Jeep 4L

[br1anstorm]

XJ reliability - good engine, take care of the body

I agree with previous posts. Look after the 4.0 litre engine (like John B, I recommend Mobil 1) and it will last well. Mine's done 120k and hasn't missed a beat.

Now the body... that's another matter. Unibody structure is OK, but why doesn't the factory rustproof them properly? The forums are full of pics of XJs with rusted-through floorpans, and there seems to be a lucrative business in replacement pre-formed floor panels. Salty winter roads are deadly (and there's that pesky aircon-drain leak which soaks the soundproofing under the carpet and rots the footwell). If you have an XJ with body in good condition, then rustproof it well (Waxoyl, Dinitrol, or similar). More important to protect the outsdie than to Herculine the inside!

br1anstorm

 

[jerdog53]

I have or have had 4 of them and none of them ever gave me any trouble the highest mileage unit was in a 77 CJ5 and went over 180K on it before the compression was to low to work with. After a ring and valve job it was like new again. I have a 2001 WJ with 88K on it now and have done nothing to it but fuel oil water. My 05 LJ Ruby has 25K on it with out any problems. I had a 83 CJ5 with the 258 I6 in it and the vacuum hoses dry rotted out after ten years and caused problems but once I replaced all that it worked much much better.

 

[Incadude]

One stop shopping:

Jeepforum.com Under Vehicles for Sale

There you'll find numerous XJ's bone -stock to fully loaded. I'm always amazed at how low the price is on these. It really makes a mod’d-up XJ real tempting. O, and don't worry too much about the I6, super strong, super reliable...

Best of luck.

 

[XXXpedition]

i can only add:
mine had 250k and was still running strong. only parts i changed:
water pump, alternator, pumer steering pump...
i know of 3 other cherokees with 200k-350k on the original engine...

do i need to say more ))
i'd only stick with a 94 or younger because of the high output engine...
sven

 

[calamaridog]

In this day and age there is no excuse for any engine not to offer reliability into the 150k range. Pushing beyond 200k is nice however:REOutArchery02:

The 4.0 I6 was a good motor and it is a real shame that Dailmer did not update the motor to meet current emmissions laws

 

[RunninRubicon]

Hesco

Did you know Benny down at our friends in Burmingham, Alabama built that beautiful aluminum super-free flowing cylinder head in an attempt to sway MOPAR to contiue to use the I-6. It would have given the 4.0L I-6, 30moreHP and 35 ft lbs of torgue more then the 2006 of 190hp and 235. This head added to a 4.6L stroker kit, a mild cam for emissions sake will net 300hp and about 365fl lbs of torgue! MOPAR saw a chance to increase the profit potential by using a motor less expensive to build an one that can be used in a multitude of autos. The I-6 could only live in a Jeep. It's all about $$$.
I read in 4wd and Sport Utility mag that a CRD is coming to the Jeep line-up for the USA. Ford is going to use a Land Rover diesel in some of its vehicles.
Toyota and GM both use input from Isusu for diesels for their line of vehicles. If I read between the lines I can see Bio Diesel as our future. Invest now. E-85 here we come!

 

[toledotimber]

Although I have a cowl snorkel on mine, I sank it in 4 1/2' of water last October, and all I had to replace was the upstream O2 sensor. These engines are very durable (cast irons heads AND blocks!). Stay away from 2000s and '01s due to potentially getting the notorious 0331 model head casting. It is known to crack between (IIRC) the number 3 and number 4 cylinders. Also, up to '99 they came with stronger high-pinion Dana 30s.

 

[RunninRubicon]

Durability!!!

Although I have a cowl snorkel on mine, I sank it in 4 1/2' of water last October, and all I had to replace was the upstream O2 sensor. These engines are very durable (cast irons heads AND blocks!). Stay away from 2000s and '01s due to potentially getting the notorious 0331 model head casting. It is known to crack between (IIRC) the number 3 and number 4 cylinders. Also, up to '99 they came with stronger high-pinion Dana 30s.

A friend in my Jeep group rolled a 05' LJ Rubi last year. It rolled three times and totaled the body. After putting it back on it's feet and out of the trees, we pulled the radiator support back from the fan, pulled the plugs and cranked it over to blow all the oil out of the cylinders. Replaced the plugs, added three quarts of oil and a bit of power-steering fluid and cranked it up! He drove it 17miles back to the highway then drove 50mph another 20miles back to the guys house! Never got hot nor lost oil pressure. Had to add a quart to the auto tranny but it shifted perfectly!. The motor has seven main bearings!. V8's have but 5. TUFF engines! Tuff as a Timex-takes licken and keeps on ticken!

 

[BigAl]

I just killed a 230K 4.0 last year by inhaling some water. If I hadn't, I'm sure it would still be running strong, it didn't smoke or use oil. It had a little noise from the valve train.

 

[XXXpedition]

with the 250k i had on mine i never put in any oil inbetween oil changes.
perfect...