JK cooling failures on the 3.6 Pentastar cluster in two places: the plastic thermostat housing at the front of the engine, and the water pump behind the timing cover. Mopar 5184651AJ is the current housing assembly, thermostat included. Mopar 68079412AE is the current pump. They leak differently, and installing the wrong one is a common way to spend a weekend and still have a puddle.
The housing is the one owners smell first: sweet coolant, crusty residue at the front of the engine, or a heater that blows lukewarm. The pump is a bigger job because the 3.6 drives it off the timing chain, not the serpentine belt. Confirm the leak is actually the pump before you open the timing cover. The housing and the oil cooler in the valley can both drip from above and look like a pump leak from underneath.
2013–2018 JKs call for Mopar 10-year/150,000-mile OAT coolant, sold premixed as 68163849AB. 2012 used the shorter-life formula. Mixing them is a separate problem from the part you just installed. The 3.6 traps air, so a housing or pump job that is not bled can overheat or set a P0128 with new parts on it.
What this category covers
- Thermostat housing assembly 5184651AJ for the JK 3.6, sold with the thermostat
- Water pump 68079412AE, timing-chain driven, behind the cover
- Why the housing, the pump, and the valley oil cooler get blamed for the same drip
Parts in this category
Each row links to the child part page for that SKU: the current Mopar number, what it supersedes, aftermarket cross-references, failure symptoms, and whether to rebuild or replace. Every number on those pages cites a source.
| Part | Mopar # | Fits |
|---|---|---|
| Thermostat Housing Assembly (3.6 Pentastar) | 5184651AJ | 2012–2017 Wrangler and 2018 Wrangler JK with the 3.6 Pentastar. Not the 3.8 (2007–2011) and not the JL. |
| Water Pump (JK 3.6 Pentastar) | 68079412AE | 2012–2017 Wrangler and 2018 Wrangler JK with the 3.6 Pentastar, per Mopar dealer catalogs. Not the 2007–2011... |
When to replace
Replace the housing as a complete assembly. The plastic is what cracks; a thermostat-only swap leaves the failed part in the engine. The housing bolts are torqued in inch-pounds, not foot-pounds. The part page has the figure. A foot-pound wrench overtightens them. Replace the pump as an assembly. It is not a home rebuild. Use the OAT coolant already in the Jeep and bleed the system. If you only need fluid, the maintenance page lists 68163849AB.
Safety
Hot coolant is pressurized. Open the cap only on a cold engine. A 3.6 that overheats on the trail can warp a head; if the gauge climbs, shut it down instead of nursing it home. Do not mix coolant types to top the system off. If you are not set up to bleed it, a shop visit is cheaper than a second overheat.
Related guides
Other systems
- JK Brakes & ABS
- JK Engine
- JK Steering & Suspension
- JK Heating & A/C
- JK Electrical
- JK Body & Doors
- JK Fluids & Filters
- JL Brakes & ABS
- JL Cooling
- JL Engine
- JL Steering & Suspension
- JL Electrical
- JL Fluids & Filters
Part numbers change as Mopar supersedes them. Match the number on your old part, or run the VIN at a Mopar counter, before you order. Back to the parts lookup.