Topic:
Exhaust gas test:
We carry out an exhaust gas test when there is coolant loss without any external leakage. With the exhaust gas tester, the presence of exhaust gases in the coolant is measured. When this is the case, the head gasket may be leaking. The coolant can end up in the combustion chamber (causing the level in the reservoir to drop), but as a result, the exhaust gases can also enter the cooling system.
The exhaust gas tester is shown in the image. With the engine running and warm, the exhaust gas tester is held above the coolant. The cap of the expansion tank or the radiator cap must of course be removed.
The tester contains blue test fluid. By repeatedly squeezing and releasing the air bulb at the top of the tester, air is drawn in. The fluid in the tester changes from blue to green when CO (carbon monoxide) is detected. When the fluid turns green, it is certain that carbon monoxide is present in the coolant and that there is very likely a defect in the head gasket.
The operation of the exhaust gas tester can also be checked by exhaling against the bottom and squeezing the air bulb. The CO present in the exhaled air will also cause the fluid to change color.
To turn the fluid blue again, the air bulb must be squeezed several times to allow outside air to flow past the fluid. The fluid will slowly return to its original color.
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