18149-ZY3-A01 Exhaust Guide Seal B - Overview. The 18149-ZY3-A01 Exhaust Guide Seal B is a specialized, high-quality rubber seal engineered for Honda marine engine exhaust systems. Its primary function is to prevent water intrusion into the exhaust system, thereby ensuring the effective operation and longevity of the exhaust components. This part is integral to maintaining seamless exhaust water flow and preventing mechanical disruptions that could compromise engine performance. Designed to meet