How tough is it? I have seen on blow a head gasket with 15 psi of boost, put a new head gasket in and it fired right up!
It's still going pretty good still.
So how tough are they exactly?

 

Mine sucked water (once), sat in water (once durning senior skip day) left her running though for safety sake.

 

In my experience it will outlast the bodywork quite happily - especially the floors and cills.

 

I've had numerous jeeps XJ's and a zj always with the l6 with over 200k never had any major engine problems at all. My current 00 is at 163. I consider that just broken in. You really can't go wrong with the 4.0. They take a beating and always come back for more.

 

Very true. You can expect the body to rust away before that 4 liter gives up

 

I have seen a xj with 4.0 that has over 300,000 on the clock

 

their tough as nails, i sucked in a ton of water through my air filter and backfired like a shotgun so much but kept it floored and suckin water and fuel and air and that thing hasnt died, ran home on a empty radiator, and had to run 2 stroke mix because its all i had, and all ive done is change the rear main because thats a weak point and it wasnt even my fault, did an oil change, and new plugs when i got it! ive seen my buddy run his on 3 cylinders to get home...

 

I found this last week

http://www.allpar.com/old/high-miles/richey.php

 

My '94 is over quarter of a million miles.

Castrol 10W-40 every 3500/AX-15 tranny 75-90 lube

 

My DD



90 renix

 

It's really tough. Can't kill that 4.0L.

 

Whenever someone questions me on how tough the 4.0 is I always tell them to check out the videos of dealers trying to kill the l6 during cash for clunkers. They go forever with the equivalent of liquid glass in them. Sometimes hours! Blowing holes in the block but still running. I've seen plenty examples of this.Then you see videos of other vehicles and it takes about 5 seconds and the motors give out. There is a video of a wj that they pour the glass in and after like an hour and a half it seizes. Then they show the next day the jeep starts right up with a hole in the block and the connecting rod just being thrown around . They are a very very tough motor.

 

we did a zj at my dealer that laster about 10 mins

 

I ran an 89 with NO coolant until it seized up while driving. Started it hours later still without coolant and it ran like there was never a problem. Not even a tick

 

i ran my 96 4.0l with no coolant for about 20 munites, hard wheeling in 4 low reason being is, i crashed in a place i was not sopposed to be, the radiator pissed everywhere and i still drove it back to my camp spot, no coolant, so we used pond water, drove 100 miles home with pond water as the cooland