Pentastar Cylinder Head Failure — What Wrangler Owners Need to Know

The Left Head Problem

The early 3.6L Pentastar engines built from 2011 through early 2013 have a known issue with the left cylinder head (driver's side). The valve guides wear prematurely, causing excessive oil consumption and eventually valve train noise. This is a design flaw in the left cylinder head casting that was revised in later production. The right bank cylinder head does not have this problem.

The root cause is a casting issue that allows the valve guides to wear oval instead of staying round. Once the guides wear beyond specification, the valves do not seat properly. Oil seeps past the valve stem seals and into the combustion chamber where it burns off. The result is increasing oil consumption that gets worse over time. If left unchecked, the excessive valve guide clearance can lead to valve breakage, which destroys the engine.

Symptoms to Watch For

The first symptom is oil consumption that gradually gets worse. A healthy Pentastar might use half a quart between 5,000-mile oil changes. A Wrangler with left head wear can use a quart every 1,000 miles or less. The second symptom is a ticking or tapping noise from the left side of the engine that gets louder as the engine warms up. This is the valvetrain making noise because the rocker arms are operating at incorrect angles due to the worn guides.

Check by removing the oil fill cap and looking at the left side valve cover area while the engine is idling. If you see excessive oil vapor or smoke coming from the oil fill opening, the guides are likely worn. A compression test will show lower numbers on the left bank cylinders. A leak-down test is more definitive and will show air leaking past the valve seals on the left bank.

The Fix

The permanent fix is to replace both cylinder heads with the updated casting. Chrysler revised the left cylinder head design in mid-2013 and the updated heads do not have the guide wear problem. Expect to pay $2,500 to $4,000 for the repair at a shop. The updated heads are about $600 each plus gaskets, bolts, and labor. Many owners choose to replace the timing chain and water pump while the engine is apart since the front cover has to come off anyway.

Some owners try to save money by replacing only the left head, but this is not recommended. The right head uses the same casting and may develop issues later. Replacing both heads at once adds only the parts cost for the second head since the labor is mostly the same. The updated heads are a permanent fix — once installed, the problem does not come back.

Bottom Line

If you own a 2012-2013 Wrangler with the 3.6L Pentastar, watch for increasing oil consumption and ticking from the left side of the engine. Catching the valve guide wear early lets you replace just the heads instead of the entire engine. The updated cylinder heads are a permanent fix for this known issue.

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