Hey, I know it's almost impossible to diagnose a sound without hearing it first-hand but I figure it's worth a shot. My Merc has started making a gear whine type of sound at idle only while in neutral. Sound instantly goes away the second I put it in gear either fwd or rev. Previous owner said he had not done the water pump and he had the boat for 5+ years. There's good water flow but thought I'd mention it. Any ideas? Thank you in advance
2002 Mercury 90HP ELPT 4S
Serial #0T562954