How to Replace a Thermostat in a Truck

The engine cooling system on your vehicle is designed to counteract the natural heating of the engine caused by the internal combustion process. One safeguard in the system is your thermostat. This component takes a lot of abuse and occasionally needs to be changed. Swapping out a new thermostat for the old takes only a little time, a couple of tools, and some know how.

Instructions

1

Allow your engine to cool completely. Open the hood of your vehicle and let the engine cool for one to two hours. Remove the radiator cap from the radiator and slide your drain pan under the drain cock on the bottom of the radiator. Open the drain cock on the radiator and allow it to drain completely into your drain pan. Close the drain cock and remove the pan from under the vehicle. Place the lid on your drain pan and put it in a safe place for disposal later.

2

Locate and remove the thermostat housing. Find the top radiator hose on your truck, follow the hose to the engine block, this is where your thermostat housing is located. Remove the two bolts holding the housing to the engine block with your socket and ratchet and set them aside for re-installation. Place a rag on the top of the housing and tap on it with the handle of your ratchet to knock it loose from the engine block. Note the proper position of the thermostat, remove it and set it aside for disposal.

3

Clean and prep the housing for installation. Stick a clean, dry rag into the thermostat hole on the engine block and another into the thermostat housing to prevent contamination of the coolant system. Scrape both the block and the housing with your putty knife to remove the old gasket and any debris. Wipe the surfaces with a clean rag to remove any residue. Remove the rags from the block and the housing.

4

Open your tube of room temperature vulcanizing (RTV) sealant, turn the cap of the RTV tube around, and use the built-in tool to puncture the diaphragm in the tip of the tube. Remove the cap from the tube and place the tip of the tube against the thermostat housing. Squeeze the tube and place a bead of sealer around the facing of the housing to create a new gasket. Allow the RTV sealant on the housing to sit and cure for 10 minutes.

5

Place your new thermostat into the block in the same position the old one was sitting. Slide the housing carefully into place on the block. Be sure not to smear the RTV sealant on the housing compromising the integrity of the new gasket. Press the housing firmly into place and install the retaining bolts. Twist the bolts through the housing and into the block by hand and snug them tight with your socket and ratchet. Allow the vehicle to sit for two hours before running the engine.

6

Fill the radiator with coolant and start the vehicle with the radiator cap off. When the system heats up it will flush the coolant into the engine and leave room in the radiator for more coolant. Replace the radiator cap when the radiator is full. Check the coolant level the next morning and top off as necessary.