Chrysler has seen a lot of success with its Pentastar 3.6-liter V-6, which was introduced in the 2011 Jeep Grand Cherokee. However, the engine appears to have a major flaw – dealers have been quietly replacing cylinder heads on many Pentastar-equipped cars.
The affected engines – which Automotive News reports to be just 0.5 percent of all Pentastars built – need to have their cylinder heads replaced due to damage. Chrysler has yet to fully disclose what causes the heads to malfunction, but Chrysler chief of engineering Bob Lee told AN that "You have to have this [low-quality] fuel characteristic, you have to have this drive cycle -- and all of these things have to line up in order to have this situation occur." The manufacturer also states that the issue is not related to the V-6's merged exhaust outlet design.
Pentastars that may be affected by the malfunctioning cylinder heads often have a ticking noise coming from the left side of the engine, says AN. If the cylinder heads do malfuction, it could cause engine misfires (especially in cylinder number two), stalling, and the aforementioned tick; all affected engines will also display a check engine warning light. All repairs are being performed under warranty, but AN reports that there has been a multi-week-long backlog in Chrysler producing the replacement cylinder heads, leaving owners in rental cars while they were waiting for the replacement parts. The automaker is already building new Pentastar engines with the upgraded cylinder heads and produced enough replacement parts to cover the backlog. AN reports that complaints haven't exceeded 500 cases per week and that only around 7500 vehicles should be affected. Chrysler had yet to respond to our requests for comment at the time of publication.
Chrysler currently builds the Pentastar V-6 at its Trenton Engine Plant in Trenton, Michigan and Saltillo South Engine Plant in Coahuila, Mexico; it also will build them at its Mack Engine Complex in Detroit later this year. Almost all of Chrysler's vehicles offer the Pentastar, including the Chrysler 200, 300, and Town & Country; the Dodge Avenger, Challenger, Charger, Durango, Journey, and Grand Caravan; the Jeep Grand Cherokee and Wrangler; and the 2013 Ram 1500.
UPDATE: We heard back from Chrysler representative Eric Mayne who told us "Chrysler Group discovered an anomaly that may affect 0.5 per cent of Pentastar engines, but only if those engines are subject to a rare set of conditions. Measures have been taken to prevent the anomaly, which manifests itself in a warning light and does not disable the vehicle. Actions have also been taken to resolve a related parts backlog. Dealers now have sufficient inventory to respond to customers should they experience a problem."
Source: Automotive News (Subscription required)