Jeep 4.0 High Output Durability

Jeeps come with brake lights, but there is no stopping the 4.0L inline six.

The 4.0L inline six-cylinder Jeep engine, including the "high output" version of the 1990s, is a very durable engine. A descendant of the 4.2L AMC engine of the 1960s, the modern Jeep 4.0L engine regularly lasts 200,000 to 300,000 miles or more.

Mileage life

According to testimony on American Used Cars, the 4.0L Jeep engine regularly reaches mileage of up to 250,000 and still runs strong. One Jeep enthusiast writes, "Basically, you cannot kill the 4.0L."

Extreme mileage

One Jeep Cherokee owner on Automotive Forums claims to have reached 350,000 miles on a 1988 4.0L engine. That vehicle now has 410,000 miles and counting.

Potential Problems

Problems with the 4.0L engine are uncommon. Some owners report trouble with the oil pressure at idle speed. However, this is often not the oil pressure itself but rather a faulty sending unit (sensor). Other problems occur not with the engine itself but with accessories such as fuel injectors, exhaust manifolds and emission control systems.

References

• Foreign and American Used Cars: Jeep Wrangler
• Automotive Forums: How Long Can A Jeep Cherokee Last?

Resources

• North American XJ Association
• Jeep Forum