Siphon Breaks and Engine Failures
Gordon Croudace

May, 2007 Hull #: , C380 #18

The head on my C380’s Westerbeke engine recently underwent a costly overhaul as a consequence of seawater entering the engine exhaust manifold. It was determined that the siphon break [aka “anti-siphon valve”] had seized shut, allowing seawater to flood the engine exhaust manifold after engine shut-down. Having discussed this with various marine engineers involved in engine overhauls, it is likely that the lack of attention to siphon-break maintenance, and sometimes the installation approach, is the cause of many failures of inboard marine engines, irrespective of manufacturer. It can affect any engine mounted below the water line, in both sail and power boats. This unfortunate experience [perhaps fortunate for our readers- Warren], has prompted me to write this article in the firm belief that all owners should understand the role of the siphon break and inspect