The thermostat block the coolant indigenous flowing right into the radiator together the engine is warming. A fault through the thermostat can reason reduced engine performance and also overheating, generally seen on the tool gauge panel.

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This article uses to the evade Ram third Generation (2002-2008).

Thermostats manage engine temperature through opening and closing the i to the radiator. Once the engine is first started, it needs to warmth as rapid as possible. Maintaining coolant from getting to the radiator speeds up this process, to reduce wear and also emissions. Thermostats usage both seals and springs come move and block coolant flow. No electronic devices are supplied to make the thermostat operate. Instead, a wax pellet the melts as soon as the coolant get a specific temperature paint, etc the thermostat closed.

Thermostats can come to be stuck open or closed. A stuck closed thermostat will cause the engine to operation cooler than normal, if a stuck open thermostat can reason the engine come overheat very quickly.


Materials NeededSocket set (10mm-18mm)Ratchet (1/2" or 3/8")3" ratchet extensionFlat head screwdriverThermostat3-4 gallons the coolant (buy HOAT (Mopar) coolant for trucks with it already installed)Drain pan3/4" wrench

The location of the thermostat because that the 5.7 hem engine and the 4.7/3.7 engines space different. On the Hemi, the thermostat is located on the engine in ~ the top radiator hose listed below the A/C compressor. The 4/7 and 3.7 engine"s thermostat is located on the reduced radiator hose close to the harmonic balancer.

Step 1 – drainpipe the coolant from the radiator

Remove the radiator lid by pushing it down, and also then twisting that counterclockwise.

At the driver"s next bottom corner of the radiator is a drainpipe blocked by a plug. Rotate this plug counterclockwise through a 3/4" wrench ~ you location a drainpipe pan in ~ it.

Figure 1. The radiator drainpipe plug.

Step 2 – remove the thermostat

To with the thermostat, you should remove the hose neck native the engine. 2 bolts hold it in place. When it"s removed, the thermostat will slide out.

Figure 2. The red circle shows the place of the hose filler neck top top the 5.7 engine.
Figure 3. A chart of the 5.7 thermostat. Number 1 shows the hose filler neck bolts. Number 2 suggests the filler neck.
Figure 4. The thermostat ar on the 4.7 and also 3.7 engines. You deserve to see the harmonic balancer at the lower right side of the image.
Figure 5. A diagram of the thermostat ~ above the 4.7 and also 3.7 engines.

Step 3 – download the new thermostat

Some thermostats come with an waiting bleed valve and notch at the edge of the diaphragm. The notch need to be filed into the new thermostat come look prefer the factory thermostat for suitable fitment with the O-ring. The bleed valve is not required; although, that does make bleeding the cooling mechanism of air easier. Transfer any gaskets native the original thermostat not discovered on the new thermostat if they room in an excellent condition; otherwise, friend will should buy brand-new ones. Make sure they are orientated properly for proper fitment right into the block and hose filler neck. The spring side that the thermostat will be facing the engine.

Bolt the hose filler neck back onto the engine v the thermostat correctly inserted inside.

Figure 6. You deserve to see the bleed valve ~ above the face of the initial thermostat ~ above the left. Both thermostats have the notch top top the edge.
Figure 7. The red arrowhead points come the slot in the hose filler neck that fits to the thermostat O-ring.

Step 4 – Fill and bleed the cooling system

You will need around three gallons that 50/50 blended coolant to to fill the cooling system. For trucks utilizing HOAT coolant, be sure to use the same type. For the 4.7 and also 3.7 engines, eliminate the top radiator hose and also fill the engine with as lot coolant together possible.

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The rest of the instructions apply to every engines. To fill the radiator, and then to fill the coolant recovery tank come the cold full mark. Leave just the restore tank"s lid off. Now start the engine and also turn the warm to the max setting. It will take number of minutes for the cooling system to warm and move air with the system. When the temperature gauge reaches about 1/4 the the way to the fifty percent mark, shut the engine off. Top off the coolant in the recovery tank as needed during this procedure. Put the recovery tank cap ago on and start the engine again. If the temp gauge rises over halfway, you may still have actually air in the system and will should repeat the bleeding procedure once the engine is cool sufficient to perform so.