Many of the AutoZone stores have a tester called the "Block Tester" in their Loan-A-Tool program. You basically put down enough $ to buy the unit (about $25) and then when you return it, you get your money back. With the "Block Tester" you have to buy the testing fluid which is $7.95 a shot. If the test is performed according to the instructions, you will know if you have a headgasket failure between a cylinder and a coolant passageway, however, there are some reports that state that fresh anti-freeze may show negative for exhaust gas contamination even when there is a small leak. The vehicle may have to be run daily for a week or so to create the anti-freeze contamination so the test kit will work to detect it.B10alia said:I would say the headgasket hinges on the compression test. You could have a coolant leak somewhere else, like the heated manifold, that's spraying coolant onto something hot and boiling it, giving you the smell. I would expect serious idling and driving problems with a badly blown headgasket. Obviously, I haven't seen the car and how it performs, so there might be something that fingers the headgasket that I haven't seen. I know that if I were you, I would want to make sure it was the headgasket before I committed to replacing it. Like I said, a compression test will be the determining factor, but I would definitely do that before anything else.
Sometimes you can sniff the overflow container and detect the smell of exhaust gas. A compression test is not helpful on a small leak that just blows a stream of small bubbles. With a small leak, the loss of compression may be very small and almost impossible to detect over several cranking revolutions. A leakdown test also may not be conclusive. The usual 2.2, 2.5 headgasket failure starts with a very small leak. A blown gasket is more of a sudden rupture of the gasket material and that type of failure is easily detected by a compression test.