On the DS Ram 1500 this is a straightforward job on the gas engines and an annoying one on the diesel. The 5.7 Hemi and 4.7 have a conventional thermostat you can swap in an hour with a 10 mm socket, hose clamp pliers, and a drain pan. The 3.6 Pentastar sells the thermostat only as part of a sealed plastic housing with an integrated temperature sensor, so plan on buying the whole unit.
The 3.0 EcoDiesel uses an ECM-controlled electric thermostat buried under intake plumbing; budget triple the time and expect to pay a lot more for the part. The single thing people get wrong on all four engines is the refill: if you just dump coolant in the radiator and drive off, an air pocket stays trapped under the thermostat and the truck overheats or blows cold heat. Use a spill-free funnel, run it to temperature with the heater on full, and top off twice.
| Item | Type | |
|---|---|---|
| Floor jack 2-ton minimum Lift the front of the truck to reach the radiator drain and lower hose. | Required | shop |
| Jack stands 3-ton pair Support the truck while you work under the front end. | Safety | shop |
| Drain pan 3 gallon or larger Catch the roughly 2-3 gallons of coolant that comes out. | Required | shop |
| Socket set 8, 10, 13, 15 mm 6-point, 3/8 in drive Housing bolts (10 mm on 3.6 and 5.7), hose worm clamps (8 mm), skid plate and bracket bolts. | Required | shop |
| Ratchet and extensions 3/8 in drive, 3 in and 6 in extensions, swivel The lower housing bolts on the Hemi sit behind the A/C lines and need a wobble extension. | Required | shop |
| Hose clamp pliers Spring/constant-tension clamp pliers, cable type preferred Factory radiator hoses use spring clamps that are hard to open by hand in tight quarters. | Required | shop |
| Hose removal tool or pick set Right-angle picks Break the hose loose from the neck without tearing it. | Recommended | shop |
| Torx bit socket set T20-T45, 3/8 in drive EcoDiesel intake plumbing, engine cover fasteners, and some 3.6 brackets use Torx. | Required | shop |
| Flat scraper or plastic gasket scraper Clean the sealing face on the 5.7 and 4.7 without gouging aluminum. | Recommended | shop |
| Torque wrench 3/8 in drive, 10-100 ft-lb, plus in-lb wrench 20-200 in-lb Housing bolts thread into aluminum and strip easily if overtightened. | Required | shop |
| Spill-free funnel kit Universal radiator funnel with Mopar/Chrysler adapter Fills and burps the system through the pressure cap without airlocks. | Required | shop |
| Coolant tester or refractometer Verify the mix if you reuse or top up coolant. | Recommended | shop |
| OBD2 scan tool Live data capable Watch coolant temp on gas engines and read/clear P0128 or EcoDiesel thermostat codes. | Recommended | shop |
| Thermostat and gasket 5.7: thermostat with housing; 3.6: complete housing assembly; 4.7: thermostat and gasket; 3.0: electronic thermostat module On 3.6 and 3.0 the thermostat is not sold separately from its housing. | Parts | shop |
| Coolant 2009-2012: HOAT 5yr/100k (G-05 type); 2013-2018: OAT purple MS-12106 Never mix the orange HOAT and purple OAT types. | Consumables | shop |
| Distilled water 1-2 gallons For mixing 50/50 if you buy concentrate. | Consumables | shop |
| Replacement hose clamps Worm-gear, sized to lower radiator hose Optional upgrade if the factory spring clamps are weak or awkward. | Consumables | shop |
| Shop towels and parts cleaner Coolant on belts and pulleys causes squeal and mess. | Consumables | shop |
| Nitrile gloves and safety glasses Coolant is toxic and gets in your eyes when a hose lets go. | Safety | shop |
5.7 Hemi and 4.7 V8: two 10 mm (some 4.7 housings use 13 mm) bolts and a conventional thermostat with a gasket. 3.6 Pentastar: three 10 mm bolts and the thermostat comes only as a complete plastic housing with the coolant temp sensor. 3.0 EcoDiesel: Torx and 10 mm fasteners, intake ducting removal, and an electronically heated thermostat module with a wiring connector.
| 5.7 Hemi thermostat housing bolts (M6) | 105 in-lb (12 Nm) - verify in the service manual |
| 3.6 Pentastar thermostat housing bolts (M6) | 105 in-lb (12 Nm) - verify in the service manual |
| 4.7 V8 thermostat housing bolts | verify in the service manual |
| 3.0 EcoDiesel thermostat housing bolts | verify in the service manual |
| Radiator drain cock | Hand tight only |
Housing bolt sizes (mostly 10 mm on 5.7 and 3.6) and the general layout are reliable across this generation, but bolt counts and the exact torque figures vary by engine and year, so confirm torque and thermostat orientation in the FSM for your specific build.
It is in a housing at the front center of the engine block where the lower radiator hose attaches, below and behind the water pump pulley. Two 10 mm bolts hold it on, and access is easiest from underneath with the splash shield off.
No. Chrysler sells the 3.6 thermostat only as a complete housing assembly with the thermostat and coolant temperature sensor built in. Aftermarket versions of the full housing are available and cost about $40-80.
2009-2012 trucks use HOAT 5-year/100,000-mile coolant (G-05 type, orange). 2013-2018 trucks use purple OAT MS-12106 (10-year/150,000-mile). Do not mix the two.
Yes. A thermostat stuck open usually sets P0128 (coolant temperature below thermostat regulating temperature) and the truck runs cold with poor heat and worse fuel economy. On the EcoDiesel a failed electric thermostat can set circuit codes and trigger reduced power.