Exhaust Flappers Products EXHAUST PROTECTOR VALVE (#47-4456) #47-4456 $40.34 EXHAUST PROTECTOR VALVE (#47-4457) #47-4457 $39.76 EXHAUST PROTECTOR VALVE (#47-4458) #47-4458 $75.64 Flapper - 3" Exhaust Valve (All Models) #106240 $5.50 EXHAUST GUARD COVER (#50-28351) #50-28351 $35.31 EXHAUST GUARD COVER (#50-28361) #50-28361 $36.24 Do flappers on a thru hull exhaust really keep the water out? When running, the engine exhaust pressure will keep water out. When the engine is idling, low RPM or off, the flappers are going to keep out water that comes rushing at the transom.
