Topic:
Smoke Test:
A smoke test is conducted when there is coolant loss without external leakage. The smoke tester measures the presence of exhaust gases in the coolant. If this is the case, it might indicate a leaking head gasket. The coolant may enter the combustion chamber (causing the level in the reservoir to drop), and conversely, exhaust gases can enter the cooling system.
The image shows the smoke tester. With the engine running and warm, the smoke tester is held above the coolant. The cap of the expansion reservoir or radiator cap must, of course, be removed.
The tester contains blue test fluid. By repeatedly squeezing and releasing the bulb at the top of the tester, air is drawn in. The fluid inside the tester changes from blue to green upon detecting CO (carbon monoxide). When the fluid turns green, it is certain that carbon monoxide is present in the coolant and that there is most likely a head gasket defect.
The operation of the smoke tester can also be checked by exhaling against the bottom and squeezing the bulb. The CO present in exhaled air will also cause the fluid to change color.
To restore the fluid to blue, the bulb must be squeezed several times to let outside air flow over the fluid. The fluid will gradually return to its original color.
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