Reasons for the Exhaust Pipe Turning Red

[VonJourney]

Automobile exhaust pipes turning red occur because some of the combustible gases from the cylinders continue burning inside the exhaust pipe. An overly lean air-fuel mixture causes slow combustion speed after ignition, extending the burning process into the exhaust stroke. Common causes for exhaust pipes turning red include: 1. Excessive valve clearance or overly soft valve springs delaying valve opening. 2. Improper valve timing with early opening and late closing angles. 3. Overly retarded ignition timing and excessive carbon buildup in the exhaust pipe and muffler. Solutions: 1. Adjust the air-fuel mixture concentration properly. 2. Inspect and adjust valve clearance. 3. Adjust ignition or fuel injection timing.