Mopar 5184651AJ (also written 05184651AJ) is the current thermostat housing for the JK's 3.6 Pentastar, sold as a complete assembly with the thermostat inside. The plastic housing is a well-known leak point on the 3.6. Owners usually notice a sweet coolant smell, a crusty residue at the front of the engine, or a heater that blows lukewarm.
Fitment
2012–2017 Wrangler and 2018 Wrangler JK with the 3.6 Pentastar. Not the 3.8 (2007–2011) and not the JL. Always confirm the number on your old part or run your VIN at a Mopar parts counter before you order.
Common failure symptoms
- Coolant weeping or white/pink crust at the housing on the front of the engine
- Low coolant with no obvious puddle
- Temperature gauge stays low and the heater is lukewarm (thermostat stuck open)
- Code P0128 (coolant temperature below thermostat regulating temperature)
Cross-reference
| Brand | Part number | Notes | Source |
|---|---|---|---|
| Mopar | 5184651AJ | Current number. Supersedes 5184651AF, AG, AH, AI and 5184655AD. Includes thermostat. | source |
| Dorman | 902-852 | Housing, thermostat (rated 203°F) and gasket. Listed for 2012–2017 Wrangler and 2018 JK. Does not fit JL. | source |
Rebuild, repair or replace?
Don't try to swap just the thermostat; buy the whole assembly. The housing itself is what cracks and warps. If you want the revision Chrysler actually updated, get 5184651AJ from a dealer. If you need it tomorrow, the Dorman 902-852 is the listing that is actually for sale on Amazon, though reviews on its durability are mixed. The housing bolts torque to 106 in-lbs, which is too light for a ft-lb wrench. The 3.6 traps air, so bleed the system properly afterward or you can get overheating and a P0128 even with new parts.
Coolant matters too: 2013–2018 JKs use Mopar 10-year/150,000-mile OAT (68163849AB premix). 2012 used the 5-year/100,000-mile formula. Don't mix them.
Where to buy
- Dorman 902-852 thermostat housing assembly (JK 3.6 only)
- Mopar 68163849AB 10-yr OAT coolant, 50/50 premix
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FAQ
Does the thermostat come with 5184651AJ?
Yes. It's sold as an assembly with the thermostat installed.
Will this fit my JL?
No. The JL 3.6 uses Mopar 4893926AH and a different bolt pattern.
Why does it still overheat after replacement?
Usually trapped air. Raise the front of the Jeep and bleed with a spill-free funnel, as described in our guide.
Related guides
Sources
Part numbers and fitment were checked against the sources above on October 22, 2026. Mopar supersedes numbers over time. If a newer letter suffix shows up, it generally replaces the one listed here. Back to the parts lookup.