The surfaces of liquid fueled rocket engine thrust chambers, throats, and nozzles are exposed to high pressure combustion products at temperatures up to 6000°F requiring the copper alloy surfaces in these areas to be actively cooled. Regenerative cooling is widely used for liquid fueled rocket engines causing the fuel to reach temperatures where carbon deposits (coke) form on the heat exchanger surfaces. Coke has a much lower thermal conductivity than copper and thicknesses of only several millionths of an inch can cause the wall temperatures to reach levels where they will fail. Moreover, the intention to reuse launch vehicles increases the likelihood that over the course of multiple missions, dangerous levels of coke will be reached. Therefore, there is a need to develop a method to characterize the layer thickness so that engine lifetimes and service intervals can be predicted. Unfortunately, the small and complex channel geometry and the very low levels of coke present make this a difficult and challenging problem. Reaction Systems has identified an approach than can rapidly and accurately map the coke deposited in all flow channels in a single analysis. The method is safe and easy to use and has no potential to cause damage to the engine or leave parts behind in the channels. In addition while carrying out the mapping process our method will remove all of the coke deposits in the heat exchanger, eliminating the need to develop a separate coke mitigation technology.