Dodge introduced the 318-cubic-inch engine in the 1967 model year; the 318 quickly gained fame as a reliable and useful engine throughout Dodge's entire lineup. In the 1989 model year, the 318 engine produced 145 horsepower at 4,000 rpm and 255 foot-pounds of torque at 2,000 rpm. A 50-50 mixture of coolant and water combined with a fan and a thermostat kept the 318 at an acceptable operating temperature. Replacing the thermostat in the 318 is a straightforward task, which a moderately-experienced do-it-yourself mechanic can complete in a short time.
Instructions
- 1
Raise the front of the Dodge with a floor jack, then slide jack stands beneath the frame rails. Lower the vehicle until only the jack stands support its weight.
2Crawl beneath the radiator and slide a draincock under the radiator drain plug (located under the lower radiator hose). Loosen the draincock, by hand, and allow all of the coolant to drain from the radiator. Close the radiator draincock.
3Raise the vehicle from the jack stands, using a floor jack, then remove the jack stands from under the vehicle. Lower the Dodge to the ground.
4Trace the upper radiator hose until you locate the point where the hose meets the intake manifold -- this connection point is the thermostat housing. Remove the two bolts securing the thermostat housing to the intake manifold, using a ratchet and socket.
5Remove the thermostat housing from the intake manifold, exposing the thermostat below it.
6Grab the thermostat and pull it from the intake manifold. Take note of the position of the thermostat, as you must install the replacement thermostat in the same position.
7Scrape the mating surface on the thermostat housing and intake manifold, using a plastic gasket scraper to remove any remnants of the old thermostat gasket. Wipe the mating surfaces clean with a clean, lint-free cloth.
8Set the new thermostat in the intake manifold in the same position occupied by the old one. Place the gasket around the thermostat and line up the holes in the gasket with the bolt holes in the intake manifold.
9Set the thermostat housing over the thermostat and tighten the bolts to 25 to 30 foot-pounds, using a torque wrench and socket.
10Open the radiator cap and fill the radiator to about 1-1/4 inches below the radiator neck with 50-50 premixed coolant. Start the 318-cubic-inch engine and allow it to reach operating temperature.
11Observe as the coolant level drops several times, as air escapes from the system. Add 50-50 premixed coolant each time the level drops.
12Close the radiator cap when the engine maintains its correct operating temperature and the coolant level settles. The entire cooling system holds roughly 4-1/4 gallons of coolant.
13Transfer the coolant from the drain pan to the empty coolant bottles. Seal the bottles and take them to a local used automotive fluid recycling center. Many auto parts stores perform this task free of charge.
