What Causes a Muffled Engine Sound?

[DiQuinn]

Engine sound becomes muffled due to the following reasons: 1. Exhaust pipe blockage. After removing the exhaust pipe and starting the engine, the muffled sound disappears, power returns to normal, and the temperature does not become excessively high. 2. Carbon buildup in the exhaust pipe. Severe blockage of the exhaust passage by carbon deposits and sludge prevents the full expulsion of combustion exhaust gases from the cylinders, meaning the heat generated during engine operation cannot dissipate effectively with the exhaust gases, leading to an easily overheated engine. 3. Poor exhaust flow. This condition results in insufficient air intake, which in turn causes insufficient engine power. Cleaning the carbon deposits and sludge inside the exhaust muffler and performing a test run after thorough cleaning can resolve the issue.