Jeep Wrangler: 3.6 Pentastar Oil Cooler Housing Crack & External Oil Leak

The plastic oil cooler and filter housing on the 3.6L Pentastar V6 is prone to cracking at the housing body or at the coolant and oil passage junctions due to thermal cycling fatigue and plastic embrittlement. This causes visible external oil leaks onto the exhaust manifold area and can allow oil and coolant mixing. FCA/Stellantis issued an updated aluminium housing as the corrective service part.

• Visible oil leak or seepage from centre-top of engine near oil filter housing
• Oil film or drips on exhaust manifold, crossmember, or underbody
• Burning oil smell from engine bay during or after driving
• Oil level dropping without visible undercarriage drip
• Milky or caramel-coloured oil if coolant and oil mixing has occurred

1. 1

   With engine cold, inspect the oil filter housing and surrounding plastic body for cracks, seepage staining, or orange-brown residue.

2. 2

   Check the underside of the intake manifold area.

3. 3

   Inspect oil cap underside for milky emulsion indicating coolant ingestion.

4. 4

   Confirm whether the original plastic housing has been replaced with the updated aluminium unit.

Parts involved: Exhaust manifold.

$350 to $1,100 at New Zealand independent workshop rates. That is for this job on its own, not for the car.

An estimate, in NZD, for the repair as normally carried out. What a specific car costs depends on which part has failed and what it damaged on the way — treat this as the floor for a negotiation, not a quote.

• “Has the oil cooler housing been replaced with the updated aluminium unit from Stellantis?”
• “Has any oil and coolant mixing been noted in service history or on the dipstick?”
• “Are there any current or historic oil leaks from the top of the engine?”

The failure described above is documented in published sources — owner forums, technical service bulletins, recall notices and workshop write-ups — held in our fault database. The inspection instructions and the cost estimate are KickTyres’ own interpretation of them, and it is a starting point for an inspection rather than a manufacturer statement.