The trade publication reports that a small percentage of Chrysler-built 3.6-liter V-6 engines — also known as the Pentastar V-6 — have defective cylinder heads. A cylinder head feeds and exhausts air from the engine block as well as delivers fuel to the cylinders and covers the combustion chamber. Chrysler has designed a new cylinder head and is replacing the unit on select vehicles that have experienced the problem.
The cylinder head problem cropped up in June, when several dealerships reported that some V-6-equipped Chryslers were experiencing early cylinder head failure, according to Allpar, a Chrysler enthusiast site. On an Allpar forum, some owners of new Chrysler vehicles have reported experiencing cylinder misfirings, check-engine light illumination and stalling after just 3,000 miles, presumably related to the defective cylinder head. On the forum, the cylinder head problem was most reported on the 2012 Jeep Wrangler, which received the new Pentastar V-6 for the model year.
The Pentastar is Chrysler's only V-6 engine for its 2012 cars and crossovers. There's a 3.7-liter V-6 on the 2012 Ram 1500 and 2012 Jeep Liberty, but the Pentastar is coming to both models for the 2013 model year, Allpar says. The V-6 has a rare cylinder head design in which the exhaust passages merge into a single outlet, whereas most engines have multiple exhaust passages in the head, according to Automotive News.
Chrysler is averaging more than 500 new service requests per week for cylinder head replacements, Automotive News says. In fact, demand for new cylinder heads is increasing so fast that Chrysler cannot keep up with it; there's currently a backlog of about 1,300 vehicles, says Automotive News. The problem has been discovered in about 7,500 Chrysler V-6s, and there could be more, the publication reports. Chrysler is giving owners free rentals while it fixes the defective motors, says the trade publication.
Chrysler has declined to describe the full nature of the cylinder head problem or its method of fixing the issue to Automotive News. The cylinder head fix will be covered by each new vehicle's powertrain warranty.
Dealers Repairing Pentastars (Automotive News)
Rare Pentastar Problem (Allpar)
Chrysler Details Future Upgrades to 2012 Jeep, Dodge, Fiat Vehicles