HOW TO CHECK IF YOU HAVE A BLOWN HEAD GASKET

There's two tests to consider. One is to draw air from the radiator through a glass cylinder with two chambers partially-filled with a special dark blue liquid. If combustion gases are present, the liquid will turn bright yellow.

The second test is to add a small bottle of dark purple dye to the coolant, then check a day or two later with a black light. The dye will show up as a bright yellow stain that you can follow back to the source. If the cylinder head gasket is leaking, you'll find the dye inside the tail pipe.

You can also do a cylinder leakage test, but that won't always show up a head gasket leak. That's because the air pressure that is forced into the cylinders is considerably less than what occurs from combustion, and it may be not enough to push the air through a small leak.