Jeep 4.0 Engine Overheating and Head Gasket Failures in the TJ Wrangler and XJ Cherokee The AMC/Jeep 4.0L inline-six is one of the most iconic and durable engines ever fitted to a Jeep. Found in vehicles like the Jeep Wrangler TJ and Jeep Cherokee XJ, it earned a reputation for running well past 300,000 km with basic maintenance. But despite its legendary status, the 4.0 has a well-known weak point: it does not tolerate overheating. When temperatures climb too high, head gask
