How Do I Replace a Thermostat in a 1995 GMC Pickup?

The thermostat on a GMC pickup, like the Sonoma, is located under the thermostat housing, which is bolted onto the intake manifold. If your GMC pickup truck is not producing heat inside of the vehicle and is not draining radiator fluid onto the passenger-side floorboard, the probable cause for the lack of heat is a bad thermostat. Because of the thermostat's location on top of the engine, it's an easy component to replace. All you'll need is a kit and a few common tools.

Instructions

1

Open the GMC's engine hood and place it on the hood prop. Open the radiator cap located on the top of the radiator. Opening the cap releases pressure on the coolant system. Because the system is pressurized, do not open the cap while the engine is hot.

2

Locate the thermostat housing. The upper radiator hose connects to it. Remove the clamp that secures the hose to the thermostat housing with a flathead screwdriver. Pull the hose off the housing. Have a shop towel handy in case radiator fluid spills onto the intake manifold.

3

Remove the two bolts that secure the thermostat housing to the intake manifold using a 7/16-inch socket. Lift the thermostat off the intake manifold.

4

Remove the gasket from the bottom of the thermostat housing and the intake manifold. Use a small scraper and a shop towel to clean everything off.

5

Pull the old thermostat out of the intake manifold and place the new one into the intake. GMC engines use a jiggle valve-style mechanical thermostat. The large spring on the thermostat goes into the intake with the long pin facing into the thermostat housing.

6

Set a new thermostat gasket around the thermostat, on the intake manifold, and place the thermostat housing on top of the gasket. Secure the housing and gasket with the 7/16-inch bolts.

7

Reattach the radiator hose to the thermostat housing and tighten the clamp with the screwdriver.

8

Close the radiator cap, start the engine and check for leaks.