How to Test for Exhaust Gases in Coolant

by Allen Moore

Exhaust gases in your engine's coolant are usually a sign of a blown head gasket or cracked cylinder head. Continuing to operate your vehicle in either of these cases will quickly lead to full engine failure. If you suspect you have either of these issues, you should perform this test immediately. The test kit is available at most auto parts stores for less than $50 as of 2010. Testing for exhaust gases in your coolant will take anyone with basic auto repair knowledge less than 25 minutes.

Step 1

Open the hood of your vehicle and make sure the engine is cold to the touch before continuing. Wait until the engine has been off for at least 10 hours.

Step 2

Remove the radiator cap from the radiator filler neck by hand. Pour the leak fluid into the suction tube, both contained in the combustion leak test kit.

Step 3

Insert the suction tube into the radiator filler neck manually. Squeeze and release the squeeze bulb on the suction tube repeatedly to draw air from the coolant system through the fluid in the suction tube. The fluid in the tube is normally blue, but if exhaust gases are present in the coolant, the fluid will change color from blue to yellow.

Step 4

Remove the suction tube from the radiator filler neck. Reinstall the radiator cap and close the hood.

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