The first test is to simply add a small bottle of dark purple dye to the coolant, then you check a day later with a black light. The dye will show up as a bright yellow stain that you can follow back to the source. If you find the dye inside the tail pipe, it can only get there through a leaking cylinder head gasket. Auto parts stores have the dye for the fluid you're using it on, and those that rent or borrow tools should have the black light.
The second test involves drawing air from the radiator through a glass cylinder with two chambers partially-filled with a special dark blue liquid. You do that while the engine is running. If combustion gases are sneaking into the cooling system, the liquid will turn bright yellow. The stores that borrow tools will have this one but they make you buy your own bottle of liquid. That's because it will be rendered ineffective if it is allowed to freeze or if antifreeze gets into it. You don't want to be handed the tool with contaminated fluid and not know it. That's why they made the last person buy their own bottle of fluid too. This test only takes a few minutes so it might be less expensive to just let a mechanic do it. If combustion gases can get into the cooling system, coolant can go the other way too and get burned in the engine. That's why the coolant level goes down when there's no obvious leak.
Saturday, May 23rd, 2015 AT 10:00 PM