Survey. Your opinion on the possible application of this old valve cleaning method.

Many years (decades) ago, I owned a Ford with an in-line 6 cyl that would develop valve clatter within 40K miles. A Ford mechanic in a small town dealership did something that I repeated for the life of the car because it worked. He explained that the intake valves were getting carbon deposits that were affecting their closure and causing the noise (ticking and clicking). He then proceeded to mix equal parts of ordinary DOT-3 brake fluid and distilled water to equal about 1/2 a pint. He then poured the mixture into a spray bottle and brought the engine to a fast idle (say, 1500 RPM). As he began spraying it into the intake, he explained that you want to spray as much as possible without stalling the engine and to do it when the engine is all warmed up through and through. Well, the black %@#* that came out of the exhaust was shocking. It turned white toward the end of the treatment. Afterward, the engine purred like a kitten and ran better too. His explanation was that nothing cleans better than brake fluid and that the water component helps crack the carbon so the solution can penetrate without the brake fluid being too concentrated.
My only concern about trying this on our cars is possible catalytic converter damage. What do you think?:23: