On the DT-generation Ram 1500, the thermostat is not a puck under a metal neck anymore — it is a sealed plastic housing with the thermostat built in, bolted to the lower front of the engine where the lower radiator hose connects. That means the parts cost more but the labor is simple: drain the coolant, pull the hose, undo two or three M6 bolts, swap the unit. Most of the time goes into getting the belly pan off and refilling the system without trapping air.
The thing people get wrong is torque and coolant. These are plastic housings on aluminum, so a ham-fisted 3/8 ratchet will crack the flange or strip the threads — use an inch-pound torque wrench and about 106 in-lb. And the DT takes Mopar OAT (orange) only; dumping in green or 'universal' coolant is how you end up with a plugged heater core two winters later. Burp the system with the heater on full hot until the level stops dropping, then recheck cold.
| Item | Type | |
|---|---|---|
| Floor jack and jack stands 3 ton minimum Raises the front of the truck to reach the lower hose and belly pan. | Safety | shop |
| Wheel chocks Keeps the truck from rolling while the front is lifted. | Safety | shop |
| Safety glasses and nitrile gloves Coolant will run down your arm as soon as the hose comes off. | Safety | shop |
| Socket set, 3/8 in drive 8, 10, 13 mm 6-point Belly pan/splash shield, housing bolts and hose clamp screws. | Required | shop |
| Ratchet, 1/4 in drive with 3 in and 6 in extensions The thermostat housing bolts sit in a tight pocket behind the crank pulley area. | Required | shop |
| Drain pan 4 gal / 16 qt Cooling system holds roughly 14-16 quarts total. | Required | shop |
| Hose clamp pliers Spring (constant tension) clamp pliers, cable type preferred Factory lower radiator and heater hoses use constant-tension spring clamps that are nearly impossible to move with regular pliers. | Required | shop |
| Trim/panel removal tool set Plastic pry set Pops the plastic pushpin retainers in the lower air dam and splash shields. | Recommended | shop |
| Torx bit socket set T25, T30, 3/8 in drive Some DT splash shields and some 3.6L/3.0L housing and bracket fasteners are Torx. | Required | shop |
| Hose removal tool / pick set 90 degree hook pick Breaks the hose loose from the plastic housing nipple without prying on the plastic. | Recommended | shop |
| Torque wrench 1/4 in drive, 20-200 in-lb The M6 housing bolts thread into aluminum and plastic and are easy to strip. | Required | shop |
| Gasket scraper / plastic scraper Cleans the old seal residue off the block or timing cover face without gouging aluminum. | Recommended | shop |
| Shop vacuum or fluid extractor Pulls old coolant out of the degas (overflow) bottle before it siphons back in. | Recommended | shop |
| Coolant funnel / spill-free fill kit Universal with Chrysler/Ram adapter Makes filling the degas bottle and burping air out far easier on the DT. | Recommended | shop |
| OBD2 scan tool Bidirectional preferred (live coolant temp / DTC clear) Confirms thermostat operation, clears P0128/P0597-type codes, needed on EcoDiesel heated thermostat circuit. | Recommended | shop |
| Thermostat and housing assembly Mopar assembly for your engine: 5.7L Hemi, 3.6L Pentastar, or 3.0L EcoDiesel (heated, with connector) Factory design is a sealed plastic housing with the thermostat built in; it is sold as one unit. | Parts | shop |
| Mopar OAT coolant 10 year/150,000 mile OAT (orange), MS-12106 — 2 gallons prediluted Only OAT is approved; HOAT/green will gel or shorten life in this system. | Consumables | shop |
| Distilled water 1 gallon For mixing concentrate or topping off; never use tap water. | Consumables | shop |
| Replacement spring clamp or worm clamp Sized to lower radiator hose Old spring clamps often lose tension after being spread; a good worm clamp is acceptable insurance. | Consumables | shop |
| Shop rags and coolant-safe cleaner Coolant on a hot exhaust smokes and coolant on the driveway attracts pets. | Consumables | shop |
5.7L Hemi eTorque: housing at the lower front passenger side of the timing cover, two or three M6 bolts with 10 mm heads, no electrical connector. 3.6L Pentastar eTorque: similar plastic housing low on the front of the block, fasteners can be 10 mm hex or T30 Torx depending on build date. 3.0L EcoDiesel: electronically heated (map-controlled) thermostat with a wiring connector, deeper in the front of the engine, usually requiring an intake tube or bracket to come off first and taking roughly twice the time.
| 5.7L Hemi thermostat housing bolts (M6) | 106 in-lb (12 Nm) — verify in the service manual |
| 3.6L Pentastar thermostat housing bolts (M6) | 106 in-lb (12 Nm) — verify in the service manual |
| 3.0L EcoDiesel thermostat housing bolts | verify in the service manual |
| Lower splash shield / belly pan bolts (M6) | about 70-90 in-lb (8-10 Nm) — snug only |
| Front wheel lug nuts (if wheel removed for access) | 130 ft-lb (176 Nm) |
The 10 mm / M6 housing fasteners and the roughly 106 in-lb figure are correct for the 5.7L and 3.6L plastic thermostat housings, but bolt head types vary slightly by build date and the EcoDiesel spec and access steps should be confirmed against the FCA/Stellantis service procedure for your exact year.
Low on the front of the engine, on the passenger side of the timing cover, where the lower radiator hose attaches. You reach it from underneath after removing the lower air dam and splash shield — it is not accessible from the top of the engine bay.
No. You drain the system by disconnecting the lower radiator hose, which is why spring clamp pliers and a 16-quart pan are on the must-have list. Pull the coolant out of the degas bottle first so it does not siphon back in.
Mopar 10 year/150,000 mile OAT coolant (MS-12106), orange, for all three engines. Do not mix in HOAT or generic green coolant; buy prediluted 50/50 or mix concentrate with distilled water only.
Yes — a thermostat stuck open typically sets P0128 (coolant temp below thermostat regulating temperature) and gives poor heat and lower fuel economy. On the 3.0L EcoDiesel, a failed heater element or unplugged connector on the map-controlled thermostat will set its own circuit code, so plug it back in and clear codes with a scan tool after the repair.