Jeep Wrangler High Mileage Problems: Maximum Reliable Miles

Jeep High Mileage Problems

How many reliable miles are owners getting from their Jeep Wranglers? This article will discuss the potential problems you can expect after 100k miles and a few preventative maintenance measures you can take to ensure many happy miles with smiles in your Jeep. Is buying a Jeep Wrangler with 100K + miles considered to be the death sentence? We will cover what to look out for when buying a used Wrangler and if the high mileage affects your Jeeps resale value. Let’s see…

Jeeps engines are widely considered to be bullet-proof and reliable. High mileage Wranglers should not be your main concern but rather how the Jeep was maintained. Year models between 2000 and 2001 which used the 0331 cylinder head were prone to cylinder head cracking and oil leaks. The Jeep Wrangler 3.8 engines fitted with 42RLE 4-speed automatic transmissions were prone to overheating. Thoroughly inspect the undercarriage for deep scratches and scuff marks which will indicate off-road abuse. Make sure the engine idles smoothly and accelerates without hesitation.

Owning a Jeep with high mileage is not necessarily a problem for most owners, however what if you intend on purchasing a used Jeep Wrangler, what signs should you look out for?

Download your FREE Jeep Wrangler Troubleshooting Guide Here

Jeep Wrangler Known Issues

Inspect the chassis and undercarriage for rust and off-road abuse

Before purchasing a used Wrangler, forget about the mileage for a while as there are other more important issues you need to be aware of before mileage is even mentioned. The Wranglers are very well built engines however, certain year models were prone to have some reliability issues. For example, The Pre 2012 JK with the 3.8L V6 engines were prone to consuming oil. It was also not uncommon to hear of gasket failures on the intake manifold as well as exhaust manifold cracking. These 3.8L engines can destroy piston rings and spin the main bearing with as little as 100,000 miles on the clock. Thoroughly inspect high-mileage versions before you commit. Even the newer 3.6L Pentastar engine has been known to burn oil. There were initial head issues on the 3.6L but these were recalled and rectified under warranty.

Your initial inspection will cover the usual checks, for example:  

  1. Inspect the undercarriage
  2. Check all ware on the ball joints
  3. Wheel bearings should still be factory standard at 100K miles
  4. Check tires, for uneven wear and cracks
  5. Thoroughly inspect the chassis and body for surface rust.
  6. Check chassis for any signs of off-road abuse
  7. Check skid-plates for dents caused by extreme off-roading
  8. Badly installed suspension modifications and upgrades.
  9. Inspect the condition of the axle U-Joints
  10. Check for rust around the front and rear shackle mounts
  11. Check for rust around the frame of the steering box

Ensure you do your homework thoroughly and be aware of the year models that were slightly problematic. Models between 2000 and 2006 used the 0331 cylinder head. Those heads were prone to cracking between cylinder number 3 & 4. Wrangler Xj’s and the XJ’s where susceptible to this mainly due to high production quantities. After 2001 the cylinder head defect was corrected and the problem was subsequently resolved. There was never a recall from Jeep to rectify the problem. It is recommended to avoid year models between 2000 and 2001 unless the cylinder head has been upgraded.

Here is a real-world example of the symptoms of a cylinder head failure:

I was sitting at a drive-thru and noticed the oil pressure was down a tad below 20 on the factory gauge….it has never really gotten below 30-35 at idle before. So last night I am searching/googling etc and stumble across all of the info about the 0331 cylinder head failures and all of the symptoms etc. Ironically, another issue I have had is losing coolant from the reservoir bottle. Mine seems to lose about a half gallon every 800 miles or so. It has never leaked, never smoked, never milk shaked the oil and the spark plugs look perfect. I never thought much about the disappearing coolant until now. After reading up in everything, it seems mine is a prime candidate for the cracked head issue. Mine is an 01 with 81k miles. I looked in the oil fill hole for the crack between cylinders 3 and 4 and can not see anything from the top yet but….all the symptoms are adding up. Yesterday I also noticed my oil level is about a half qt overfilled…..I changed the oil myself and know I got it correct per the dipstick at the last change about 1k miles ago which means the oil level is rising……(ie. Coolant mixing in with the oil).

https://www.jeepforum.com/forum/f9/ohhh-man-i-think-0331-head-curse-about-get-me-977260/

A head upgrade would be a new, stronger cylinder head from Alabama Cylinder Head, Clearwater Cylinder Heads, or using the newer (2002-2006) factory cylinder head with the additional casting of “TUPY” on it.

Also, 2005 and 2006 TJs have a poorly designed oil pump drive assembly that suffers from a lack of lubrication. The factory units are much more reliable with a grease fitting modification

Additional Jeep Wrangler Checks

Thoroughly inspect the suspension for rust and poorly installed suspension upgrades

There are more factors to consider such as suspension upgrades. These might enhance the aesthetics of the vehicle, however, you need to make sure it was done professionally since you really do not want to inherit other people’s problems.

High mileage jeeps are probably one of the safest buys you can make since they are such robust and reliable vehicles. However, it is because of this fact that some abuse them or fail to regularly maintain them. Fortunately, with Jeeps there are very few things that can go wrong and parts like clutches, brakes and timing chains should really be the least of your concerns since they are usually the last to go, provided it received regular maintenance.

Check for deep gashes and heavy scratches underneath, since these do not happen from light off-roading… Ask for the service history and make sure all maintenance and servicing was done on schedule. The service documents will reveal a lot about the history of the vehicle and what repairs have been done over the years. If well maintained these 4.0 engines can easily run into 300K miles with little hassle.

Quotes From Jeep Owners With High Mileage (100K+ miles) 

“My ’91 YJ has 168,000 on the 4.0 and runs like a top. I bought it with 145,000 3 yrs ago, changed all the fluids and u-joints immediately, and have been changing them regularly since.”

https://www.wranglerforum.com/threads/high-mileage-wranglers.79810/

“I’ve got a 98 tj 4.0 L. 340,000 miles and still going. Original everything. As long as you don’t run it to shit and keep up with maintenance, you’ll be able I get plenty of life out of your jeep. Although mine tends to eat oil quite rapidly…”

https://www.wranglerforum.com/threads/high-mileage-wranglers.79810/

“I have 185,000 on my 99 and would drive it anywhere without hesitation.”

“My 99 is at 185K with basic upkeep and minor issues, cracked exhaust manifold, and header. Other than that runs great”

https://www.wranglerforum.com/threads/how-reliable-are-high-mileage-tjs.164035/

“210k on mine, never any big problems, did a starter last year, and will do a radiator soon and water pump for preventative maintenance also”

More High Mileage Jeep Facts To Consider

  • So we’ve established the 4.0 is basically bullet-proof in factory standard form. Arguably more reliable than many Japanese derivatives if well maintained.
  • Mileage is atrocious with the 6 cylinders returning 16MPG in factory stock form. Add a lift, bumper and some bigger tires and that number drops even further. 4 Cylinders are not that great either at the pumps.
  • Jeeps hold their value very well since they are an American brand and generally well built. These engines are quite basic and super easy to work on, which means you can do a lot of the maintenance and repairs yourself with the correct tools. That approach will save you a ton of cash since parts are cheap and easy to acquire.
  • The Wranglers are a unique vehicle in that they are purpose-built and lifestyle vehicles that offer durability and reliability with a go-anywhere attitude, hence their premium price tag.
  • With Jeeps, it’s more important to stay ahead of problems and staying ahead of any problems before they crop-up is key to enjoying hundreds of trouble-free miles.
  • Miles is not as important, but rather the maintenance that will determine it’s reliability.
  • Model years 2000 and 2001 with the 4.0 came with the defective 0331 cylinder heads.
  • Opt for the 4.0L, and go with the 3-speed auto or a stick since the 4-speed auto is troublesome
  • Manuals are bulletproof but the auto tranny’s on the older models have problems after about 110,000
  • If your budget allows, look for a 2000-newer 4.0 with the coil pack ignition (no distributor/wires)
  • Look for a Dana 44 rear axle if possible. The manual transmission came equipped with them.
  • Automatic transmissions between 2007 and 2011 with 42RLE gearbox were prone to overheating.
  • The post-2012 WA580 automatic transmission was a solid gearbox. Upgrade the transmission cooler for improved reliability.
  • Do your market research and check your area to ensure you are paying a fair market price.
  • Full-service history is the key.
  • If you are comfortable making repairs and have the equipment for small to medium level repairs, you can opt for the older models. However If not, then go for a newer model with lower mileage and a warranty plan.
  • The engine in 2007 through 2011 Wranglers is a reliable design that is “tried and tested.” It’s been used in many vehicles for 20 years or so. It might not be very powerful, but it is very reliable. They have been known to burn oil.
  • Try and buy a factory standard or as close to standard Wrangler as possible. You can then later modify it how you prefer with the warranties in place.
  • I’d go condition over mileage on any TJ. The engines are strong runners. Not high compression and cast iron block. They will last a LONG time. Rust and lack of maintenance are what kills them.
  • No reason to be afraid of high mileage! As long as the engine runs well and doesn’t burn any noticeable amount of oil.
  • Check if parts have been replaced like the water pump, driveshaft’s, u-joints, rear axle seals, ball joints, and tranny oil changed.

Resources

Download your FREE Jeep Wrangler Troubleshooting Guide Here

Conclusion

High mileage Jeeps are nothing to be afraid of, provided it was well maintained. Mileage does not kill a Wrangler, it’s the rust, abuse and a lack of proper maintenance.

When you inspect, make sure the engine idles smooth and accelerates with no hesitation. Shift through the gears… Test the 4X4 system carefully and thoroughly. Crawl under the Jeep. Believe it or not, that tells you a lot about the Jeep’s past. Listen for weird noises. If you’re not familiar with this vehicle, bring an experienced friend along.  He/she will be able to tell you if anything seems off-kilter.

Jade C.

4-Wheel drives and off-road driving techniques has been my passion for over 20 years. Here we strive to provide the most accurate, up-to-date, information about the functionality, common faults and latest technology built into most 4 Wheel Drives.

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