1999 Volvo Penta "WT" Models Workshop Manual, Page 349Get this manual
Water Flow Problem Checkpoints:
Numbers refer to Cooling System Flow Diagramsdebris
CD Intake ScreenBlocked with
Water Tube Water TubePlugged Upper Pivot
Guide and SealImproperly sealedwith debris
GrommetDeteriorated, improperly seatedGear HousingDebris blocking passage, freeze
damagedHousing SealDamaged, out of position, improperly
(j) Nipple O-ringOut of position, improperly sealed, damaged
NippleBlocked by debris, freeze crackedHose and ClampsClamps loose, hose collapsed or leaking