Part of Lesson Plan: **How to make a gasket using a ball-peen hammer (updated) by Ramon C. Iniguez

Activity Overview / Details

Using a shop vehicle:

1. With all students wearing PPE properly, explain to the students that before removing the radiator cap or bolts from the thermostat housing, the cooling system needs to be cool to prevent injury.
2. Demonstrate how to drain enough coolant from the radiator to remove the thermostat with minimal coolant spill.
3. HAZMAT: Explain where to properly store the coolant drained from the vehicle.
4. Disconnect the radiator hose and remove the thermostat housing and the thermostat.

Note: Explain to the students that other components or brackets may need to be removed to gain access to the thermostat on some vehicles.

1. Scrape off the old gasket material from the thermostat housing and the engine block. Point out that cleanliness is important to a successful job. Also, point out that the gasket scraper can easily scrape skin off of your hand.
2. With the thermostat housing clean, place a piece of gasket paper over the housing.
3. Press the gasket around the thermostat housing bolt holds to make an impression of the hole on the gasket.
4. Use the ball side of a small ball peen hammer to lightly tap the inside perimeter of the hole, the ball of the hammer will cut the gasket as it strikes on the sharp edge of the thermostat housing. Place the bolts through the holes that you just cut to help hold the gasket in place (see P.P).
5. Using your thumb and fingers, press the gasket against the inside and outside perimeter of the thermostat housing, this will make an impression on the gasket and also aid in holding the gasket material in place.
6. Now cut the inside part of the gasket using the ball side of the ball peen hammer (see P.P.).
7. Next, cut the outside part of the gasket using the ball side of the ball peen hammer around tight curves. You may use the face (flat) side of the ball peen hammer on the wider parts of the housing (see P.P.).
8. Once the gasket is made with no tears on the sealing surface, install gasket, thermostat, and housing back on the vehicle.
9. Connect the radiator hose and close the radiator drain valve.
10.  Add proper coolant amount.
11. If available, attach coolant pressure tester to check for leaks.