How Do I Replace the Thermostat in a Buick 3800?

The Buick 3800 engine, used in several Buick models over the years including the Le Sabre, sported a V6 engine configuration. The thermostat on the General Motors-designed engine is located on the intake manifold. This is the easiest thermostat location for a do-it-yourself repair since you do not have to drain the radiator and work from under the car as you would with a vehicle with an engine block-mounted thermostat.

STEP 1 - Locate the metal thermostat cover on top of the Buick's intake manifold by following the upper radiator hose from the radiator to the location where the hose clamps to the engine. The hose clamps to the thermostat cover.

STEP 2 - Remove the radiator hose from the thermostat cover. If the clamp is original, use pliers to squeeze the compression tabs together then pull the hose off the cover. If the clamp is an aftermarket band clamp, loosen the clamp using a socket and ratchet. With the clamp loosened, pull the hose off the thermostat cover. Lift the hose vertically so any fluid in the hose flows into the radiator.

STEP 3 - Remove the two bolts that hold the thermostat cover onto the intake. Inspect the bolts. If they have heavy corrosion or rounded heads, discard them.

STEP 4 - Lift the thermostat cover off the intake. Sometimes the cover sticks to the intake. Push on the side of the thermostat cover to break it loose.

STEP 5 - Scrape the old thermostat gasket off the intake manifold with a small scraper. Some of the thermostat gasket may stick to the bottom of the thermostat. Inspect it and remove any gasket stuck to the bottom with the scraper.

STEP 6 - Pull the thermostat out of the intake manifold and place a new one into the manifold. The thermostat sits on a lip inside of the hole. The end of the thermostat with the large spring on it sits inside the hole.

STEP 7 - Place a new thermostat gasket onto the intake manifold and secure the thermostat cover on top of it.

STEP 8 - Slide the radiator hose onto the thermostat cover and secure it with the clamp.

THINGS YOU'LL NEED: Pliers, Socket set, Scraper, Thermostat, Thermostat gasket