1999 Nissan Altima - Whining Sounds When Accelerating

Sounds more like a bearing in the pump going bad. But change the belt first since it needs it anyway. Then you'll know for sure.

Serious tranny issue. Sorry.

A whining noise during acceleration usually, is from the gear set, indicating the pinion is too close to the ring gear.
I believe the eclipse is a FWD car though. Could it be the transmission you are hearing?

remove the belt and start the engine ..IF THE NOISE disappear it might be idler bearings that driven by belt but if the noise still there check the pcv valve..

a whining sound typically has one of three sources; alternator, power steering pump, or transmission.

I had got help from its
manual from online store www.reliable-store.com. Here's the site link I am sure they will help you

check power steering pump fluid, with engine off try to wiggle every pulley if any move at all that's your culprit, power steering, alternator, idler puller, water pump, but sounds like bearing failure

you call it the serpentine belt, we call it the fanbelt.it,needs tightening,slightly loosen the alternator, then pull away from engine and tighten belt, tight enough when you can move longest part of the belt, between pulleys, 1/2 inch in/out.
if squeel re occurs fit new belt.

The serpentine belt is the most common cause for whining sound when accelerating, try to understand if noise is coming from serpentine belt.

Also check power steering belt under steering column, and also the rotor and chain, thei do not make whining noise , but can make noise when accelerating.

The belt is first suspect.

hi more than likley to be the alternator remove your fan belt start engine see if noise disapears yates210456