Engine Carbon Build-Up

[Jim Parker Toronto]

We used to do that water trick on some of our old V8 flateads, but we never took a head off to see if it really worked, but it must have because we never had any problems even with the stale gas that we got out of the junkers at the wreckers...

[Jake]

Whats the water trick? Please explain!

[Tom Wesenberg]

Originally Posted by Jake

Whats the water trick? Please explain!

Bring the engine up to normal temp, then set the speed to fast idle and slowly pour water down the carb. The water turns to steam and removes the carbon. We also had cans of a GM labeled product that you'd pour in the carb, then the last of the can would be poured in fast enough to kill the engine. Let the engine set while the product worked, then restart the engine and take the car for a drive.

Both methods worked well, and it was best to do this BEFORE the tune up. In the 70's when I worked at the Chevy dealership as a mechanic, I tuned up a customer's car then took it out to test it and to burn out the carbon by running it down the freeway for about 5 miles at 60 MPH. A piece of carbon fouled one of the new spark plugs. That's when I learned if you have a carbon problem, you decarbon before the tune up.