1999 Volvo Penta "WT" Models Workshop Manual, Page 213Get this manual
Installation
[[] 1If installing new rubber bushings, apply 3M Scotch Grip Rubber Adhesive 1300 or OIVIC Scotch Gnp Rubber Adhesive 1300 to outside of tips, and insert into inside of exhaust pipe
2Position valve with longest lip pointing down, and insert :nto pipePush pivot pin through bushings and valve until pin end is flush with outside of pipeCheck exhaust valve for freedom of movement
INotel If valve is not positioned properly (long lip down), it will restrict exhaust flow and fail to prevent water backing up into engineBoat performance would be adversely affected, and engine may suffer water damage3Install intermediate pipe following procedure under Exhaust Hose and Pipe Replacement