BOLT 9B7237 - Caterpillar

Marine Engine:
C12 (S/N: C1Z1-UP; 9HP1-UP)
Recent testing with the wet type of exhaust systems on the above C12 propulsion engines have shown that the design of the marine muffler can have a significant effect on overall reduction of noise. Some designs of wet exhaust mufflers allow exhaust gases to pass through the muffler without passing through the water discharge resulting in higher noise levels in the passenger compartment of the boat. The most effective design of the muffler for reduction of noise is routing the exhaust gas through the water before exiting the muffler.Note: It is important to monitor exhaust back pressure in order to make sure that the back pressure limits for each engine and the application are appropriate. These back pressure limits can be found in the Technical Marketing Information (TMI), which is available in SIS.For more information, see Application and Installation Guide, LEKM7146, " Marine Engines Application and Installation Guide".