[f.monroe]

I have seen ATF , water , a combination , etc dumped down carbs or throttle bodies to loosen carbon buildup in the cylinders . An older mechanic poured water down a 4.0 L Jeep that was making a noise that sounded like a rod knock . I worked at the dealership at the time and he said there had been several problems with carbon in those engines . He revved it and started dumping the water slowly until it choked the engine down . It took a half soda can of water but it stopped the noise . That ws a fuel injected 4.0 . GM sells ( or used to ) a product called Top Engine Cleaner that is designed for removing carbon . I used it on a 1984 454 3/4 ton I had that developed a knock . After checking it out I determined it was carbon buildup in the cylinder . It took two applications but it worked . It only smoked for about a day then it was back to normal . The problem is that if liquid is poured down a running engine too fast , It can be bad . I think Holley used to sell a water injection kit in the 80's to cut down on detonation . It kept the cylinders cleaner so there werent hot spots and it cooled the cylinders a little . Frank