I've been told auto parts stores that rent or borrow tools often have this one but you have to buy the liquid. One bottle will fill the tool many times over so you're wasting your money. The fluid will not work once it gets contaminated with coolant. That's why mechanics always have extra, in case they accidentally get some coolant in it.
The fluid is expensive, and I've been told it won't work if it has been frozen. For that reason you can't buy it from the tool truck guys in the winter. It would freeze during shipping. Because of the cost, you might be better off just having a mechanic do the test. Or, at least watch him do one first. It only takes a minute. You squeeze a rubber ball and release it to draw air through the two chambers of fluid. If combustion gases are present, the liquid will turn from dark blue to bright yellow. If that happens, you simply move it to fresh air and draw that through it to turn the fluid blue again. You can use the same fluid over and over until it gets contaminated.
Here's what the tool looks like:
Tuesday, March 13th, 2012 AT 12:02 AM