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4.0L engine life

J

jpk

NAXJA Forum User
Location
Jacksonville, FL
I have a 96 XJ with 192k on the clock. I know with some average care the engine will easily do 300k. Are there any people here that have more than 300k and it just keeps going? Lets hear your mileage!
 
96 over 400,000 when the engine was pulled,it was tired but still running.
Did it for "peace of mind" before it was broken and I was walking......
 
I had an experienced mechanic tell me the 4.0 was engineered to run 250,000 miles. I trust his insight.
 
I know someone that has a 500k XJ running just fine with proper maintenance but no rebuild. I have one thats 300k, runs fine but rusty so Im restoring it and my other is at 180k. Many people have issues because of original owners having their vehicles maintained by shops which diminishes lifespan due to bad work, bad parts and horrible fluids on the rare occasion that they are changed. If you are driving this on the daily I recommend a gasket set at 300k the latest as well as looking into the cylinders to see if they need just a simple honing. Nothing too major. Assuming you need to hone the cylinders at 300k as well as replace all gaskets I think you will be fine until the dial turns back to 0 providing you are gentle with the throttle and put good fluids in. But I stress the need for good oil. Castrol Edge and a Mobil filter.
 
332K and some change on my gauges. I'm not 100% certain that my gauges match my drivetrain or vice-versa, but I'm fairly certain that they do. Bought it with 296K and would not have done so without compression and vacuum testing the engine. One thing you need to understand about the 4.0 is 1. It's a straight 6 and 2. It's built old-school with a lot of iron and such. Generally, those two factors equal a long engine life between. It's the same reason the old Ford 300's refuse to die and why just about every semi on the road today uses a diesel straight 6.
 
I know a guy still running a 1988 with the original engine at over 650,000 miles.

Personally, the longest I've had a 4.0 go is the one in my 96 ZJ at just over 255,000 miles.
 
My 01 XJ has 347,000. Because of the pesky 0331 head, I pulled the head and replaced it but otherwise the engine seems to work like new.
 
Love it. I'm thinking of changing my oil and filter combo. Currently I'm just getting what my local lube shop puts in. However I want to upgrade the materials going forward. I also want to put new spark plugs in. Any suggestions?
 
I had 360k on a renix XJ. Only reason it failed was that my ex ran it without oil for who knows how long.
 
Checking the local parts stores they list the Champion RC12LYC and there is no listing for the RC12PEC5. What is the difference? Should I just go ahead and get the RC12LYC's?
 
im somewhere in the 287,000 mile mark. it overheated twice. didn't realize the radiator blew. but it was close to -10 out at the time. stalled twice. got a radiator and filled it with coolant and haven't had an issue. removed the oil pan and valve cover and discovered a oil pan and valve cover made of sludge. just recently pulled the engine and swapped it into another jeep. the body was far to rusty. still running great.
 
Ok, the above recommended plugs are platinum. I just bought the LCY's as from what I have read the pre 2000 XJ's work better with them. Whatever that means. If they do ok I'll keep them. If not, I'll try the plat's.
 
I have used Champions in mine for years. First the SUV & truck plugs and when they discontinued them whatever NAPA said to use. I really don't find the 4.0L very sensitive to particular Champion plugs, but I haven't tried Autolite, etc. to compare. I've always just used the Champions and the 4.0's run fine.
 
md21722 said:
I have used Champions in mine for years. First the SUV & truck plugs and when they discontinued them whatever NAPA said to use. I really don't find the 4.0L very sensitive to particular Champion plugs, but I haven't tried Autolite, etc. to compare. I've always just used the Champions and the 4.0's run fine.
Click to expand...

Same here. I was running Champion single platinum (RC12PEC5) plugs in mine for a bit and didn't notice a bit of difference when I swapped back to the copper RC12LYC's. Summit Racing even sells them for the same price too.
 
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