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Jeep Wrangler Reliability

By: August 17, 20215 min

Wranglers rust. And it can be a problem, even on the more recent JK models. This isn’t because there’s something wrong with the metal used on these 4x4s, but rather because many Wranglers are driven in all kinds of weather and through mud. That moisture from rain, snow, and wet dirt gets in the SUV’s nooks and crannies, and over time it can deteriorate the steel. Plus, the Jeep’s soft tops can start to leak as they age, causing water to enter the interior and soak the carpet. 

It’s important to check for rust everywhere — the body, chassis, suspension, and floor. Look behind all the tires on the fenders and other parts. That’s where the mud can gather as it is tossed from the rolling tires as you drive. And if you can, put it on a lift and get a good look at the floors. Carpet hides rust, so you have to look from the bottom. While you’re under there, check the frame and suspension, especially the shock and body mounts.

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It’s also important to look for damage that may have occurred during serious off-road expeditions. Look for dents in the engine’s oil pan, the fluid pans for the transfer case and transmission, and the exhaust system. Have they been smashed by rocks? Small dents aren’t a huge problem, but large dents are. It’s also a good idea to check for leaks, and that inspection should include the power steering and brake fluids. 

Body damage can also be an issue if the Wrangler has spent a lot of time out on the trail. Rocks can dent the rocker panels under the Jeeps doors as well as the corners of its quarter panels just ahead of its rear bumper. Check for repairs in these areas. If there’s evidence of a repair, make sure it was done properly. Does the paint match well? Ask the owner what body shop did the work and whether he or she has a receipt.


As we mentioned, over time a Wrangler’s soft top can deteriorate and need replacing. Sun, rain, dirt, and snow can yellow the Jeep’s plastic windows, which can also become brittle. And often the material used for the top itself can stain and just look beat. Also, the zippers that hold it all together can weaken with age or become jammed. 

The good news is that replacements aren’t very expensive, so a weathered and beaten top isn’t always a good reason to walk away from an otherwise perfect Wrangler. The aftermarket is full of new soft-top options, and a quick Google search shows that replacements cost between $275 and $800. That doesn’t include the installation of course, which can be handled easily by any upholstery shop in a few hours. Aftermarket hardtops are also available, so you can switch back and forth with the seasons if you wish.


If serious off-roading is in your plans, it’s probably a good idea to spend a bit more for a TJ, JK, or JL in the Rubicon trim level. While the Dana 30 axles in other models are stout enough for most off-roading adventures, Rubicons have Dana 44 axles that are considerably more durable. More importantly, Rubicons also have front and rear locking differentials, which radically expand the Jeep’s traction and allow Wranglers to climb over rocks, up hills, and through mud that would otherwise be impossible. 

Tougher axles and locking differentials are common upgrades for Jeeps, so you can easily upgrade these components later if you wish. However, that gets pretty expensive. The parts alone will cost thousands of dollars, and the installation takes many hours.

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When you’re shopping for a used Jeep Wrangler, you’re going to find two types out there: stock and modified. The Wrangler has been called the most modified vehicle on the planet, millions have been “personalized” with lift kits, larger wheels and tires, steel bumpers, push bars, and auxiliary lighting. Most of these modifications can enhance the look of a Wrangler, giving it a tougher Mad Max I’m Ready for the Zombie Apocalypse look, and they can improve its performance off-road.

But poorly installed parts and the wrong combination of components can ruin a Jeep. It may actually perform worse. It could ride horribly. It can be simply unsafe for the road. And remember, all that stuff adds weight, so the Jeep’s acceleration can also be adversely affected, while its engine will be working harder. Look at the aftermarket parts used and their installation carefully. Does anything look sketchy? Are there wires hanging down where they shouldn’t be? Does its modified suspension seem to operate as it should? A modified Jeep can be the greatest adventure vehicle in the world, or it can be a nightmare.


In 1987, Jeep offered the YJ with either a 117-horsepower 2.5-liter four-cylinder, which features a rudimentary fuel injection system, or a 112-hp 4.2-liter inline six-cylinder with a simple two-barrel carburetor. Neither is going to win any drag races, and both have their pros and cons. The six-cylinder is considered the tougher of the two, but it can also be hard to work on, and it was paired with a Peugeot-built five-speed manual transmission that’s known to be fragile. 

In 1988, Jeep replaced the NP207 transfer case with the tougher NP231, and a year later it paired the six-cylinder with the tougher AX-15 five-speed manual. A four-speed automatic was available, but unlike today, most YJ Wranglers had three pedals. In 1991, Jeep introduced the High Output 4.0-liter inline six-cylinder with 180 hp. That engine would become very popular for its performance and durability, and if you’re going to buy a YJ, it’s the best engine option.


That 4.0-liter is also the best and most durable engine option in a TJ, especially after it got bumped up to 190 hp in 2001. TJs with the standard 2.5-liter four-cylinder, which was finally replaced by a 2.4-liter with a single overhead cam in 2003, are considerably slower, and the engine isn’t as bulletproof as the miles add up. The six-cylinder can run forever with proper maintenance. Make sure the owner changed the oil religiously.

It’s also important to crawl under and check for oil leaks. After the 100,000 miles, the 4.0-liter’s gaskets usually don’t seal as well as they used to, especially the rear main seal, which is a pain to replace. Checking the radiator’s plastic tank is also a good idea. They’re known to paint driveways as well. The tubular exhaust manifolds are also known to crack. In 2000, the 4.0-liter received more durable units with twin catalytic converters, as well as a more modern coil-on-plug ignition system. Earlier versions had a distributor and plug wires. That year, Jeep also replaced the AX-15 with the stronger NV3550 five-speed manual transmission. (It was replaced with a six-speed in 2005.) The three-speed automatic was replaced in 2002 with a four-speed unit with overdrive that greatly improved fuel economy on the highway and drivability around town.


As with any used car, if you’re shopping a JK or JL, it’s important to get a vehicle history report and read it carefully. Make sure the vehicle has been cared for properly, has received its scheduled maintenance on time, and hasn’t been totaled in an accident, burned by an angry mob, or swallowed by a flood. Look for unscheduled repairs and always ask the owner if it has been in any kind of accident, even a minor fender-bender. 

As we mentioned, many Jeeps have been modified, which is fine, but know that many of those modifications may void the manufacturer's three-year/36,000-mile warranty. That’s not an issue with a YJ, TJ, or older JK, but if you’re shopping for a later JK or a JL, it’s something to think about and research. JL buyers should also know that first-year JLs were subject to nine recalls, including one for the powertrain computer module. That’s not a big deal; most cars and trucks have been recalled for one thing or another. But make sure the used JL you’re shopping has received these important repairs. Leaky shocks have also been a problem on some JLs after 30,000 miles, but they are covered under warranty. Tires can last about 40,000, even with many miles of off-roading.


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