In May of 1984, Toyota introduced the 4Runner, a compact four-wheel-drive SUV with the same running gear as its compact truck. The thermostat is a device designed to regulate coolant flow through the radiator in order to maintain a constant engine temperature. On the 4Runner, it is located in a housing on the intake manifold, on the top-front of the engine. Follow the top radiator hose from the radiator to the engine; this will lead you directly to the thermostat housing. Very little, if any, antifreeze will be lost in this procedure.
Instructions
- 1
Open the hood and make sure that the engine is cold before starting the procedure. Loosen the clamp on the radiator hose at the thermostat housing. Pull the hose off the housing.
2Remove the two bolts that secure the thermostat housing to the intake manifold, using the appropriate size socket. Lift the thermostat housing off the intake manifold and remove any gasket residue by scraping it off with the screwdriver -- by leaving the thermostat in, you prevent any gasket material from entering the manifold.
3Lift the thermostat out of its seat in the manifold. Install the new thermostat after making sure the seal is in place around the outside diameter of the thermostat -- this is similar to a polyurethane O-ring, but has a channel that fits over the outside edge of the thermostat.
4Spread RTV silicone on both sides of the gasket that accompanies the thermostat. Place it on the intake manifold, over the thermostat, and align the holes in the gasket with the two holes in the manifold.
5Install the housing and tighten the two bolts, using a socket. Push the top radiator hose on the thermostat housing nipple and tighten the clamp with the screwdriver. Open the radiator cap on the reservoir and add water to bring the level to the "Full" mark -- a small amount is required, and it is not necessary to add antifreeze as long as the correct mixture of antifreeze to water was present before the thermostat was replaced. Install the cap.
