Troubleshooting a loud whine (2GM20F)

[SlowButSteady]

It sounds like the water pump bearing went south on you. Changing a water pump is usually a pretty easy job. On most boats the front of the block (and hence the water pump) is the only part with good access. The only tricky part is just making sure you don't snap of any of the bolts that attach the pump to the block (don't ask how I know this ).

[wescarroll]

Water pump(as stated) or alternator belt. Nothing to do with the belt directly, but once it has squealed it is junk, change it. A locked or binding water pump or alternator is the cause, change/rebuild the component causing the squeal.

[MitchM]

if you have rust in the pulley grooves it can lead to premature belt wear and 'black dust' from the belts' prematurely wearing. Rx: you can clean the grooves of rust with emery paper, it's better for the belts to run in clean grooves.

"...While coming back to my slip last sunday, a loud whine came from my engine (2GM20F). The noise goes up in intensity with rpm --yep, the freshwater pump will be running faster rpms as engine rpms increase--- and is faint and intermittent at idl. (It really sounds like rubber slipping on metal.) While manoeuvring to my slip, everything went well, so I'm assuming there was no power loss.

".. There was no smoke to be seen, but a burned rubber smell was noticed by everyone onboard..." Once stopped, I opened the engine compartment and it felt hotter than usual, but this is rather subjective.
--if your freshwater cooling pump is malfunctioning, you may have overheated some coolant hoses which is the 'burnt rubber smell.. i'd carefully check all the coolant hoses for cracks or leaks, especially the ones in closest proximity to the hot engine block. when i blew my freshwater pump the engine overheat alarm went off , but by the time i shut it down i had fried the coolant hose up near the thermostat, nearest the hot block...

on my engine i could not rebuild the a/f freshwater pump, had to buy a whole new unit $220 but it was an easy replacement and since i did it myself , saved some $$$ there.