Sodium silicate can be used to fill gaps within the head gasket
. Commonly used on aluminum alloy cylinder heads
, which are sensitive to thermally induced surface deflection, and can be caused by many things including head-bolt stretching, deficient coolant
delivery, high cylinder head pressure, overheating, etc.
"Liquid glass" (sodium silicate) is added to the system through the radiator, and allowed to circulate. Sodium silicate is suspended in the coolant until it reaches the cylinder head. At 100–105°C, sodium silicate loses water molecules to form a glass seal with a remelt temperature above 810°C.
A sodium silicate repair can last two years or longer. The repair occurs rapidly, and symptoms disappear instantly. This repair only works when the sodium silicate reaches its "conversion" temperature at 100–105°C. Contamination of engine oil is a serious possibility in situations in which a coolant-to-oil leak is present. Sodium silicate (glass particulate) contamination of lubricants is detrimental to their function.
Sodium silicate solution is used to inexpensively, quickly, and permanently disable automobile engines. Running an engine with about 2 liters of a sodium silicate solution instead of motor oil
causes the solution to precipitate, catastrophically damaging the engine's bearings and pistons within a few minutes.
In the United States, this procedure was used to comply with requirements of the Car Allowance Rebate System (CARS)