On deaccelaration i hear a load whining sound

hi, in most cases it nothing to worry about , the shaft that runs from the motor to the axle bearing , the bearing where the noise is loudest.

Brand new Scooters can develop this whining sound after only a couple of weeks. Normally louder when under load otherworld's going up hill etc.

Regards
Rob

When in Park or Neutral does the noise change if you rev the engine? Whining noise generally come from a worn bearing so there will be a few things to check.
First check the serpentine belt. A loose or worn belt will cause noise. Carefully watch the belt with the engine at idle. Does it run smoothly or 'bounce' as it spins? Bouncing could suggest the spring in the belt tensioner is worn and has started to go slack.
Stand in front of the vehicle with the hood open and carefully listen to the engine. Sometimes you can hear if it is on one side of the engine or the other.
The most likely causes of the whine will be...
Power steering pump, A/C pump, Water pump, alternator pulley, belt tensioner and it's pulley or an idler pulley.
Parts like the alternator have more than one bearing in them so that could be another area to check. If the serpentine belt is off you can spin each pulley by hand. Listen and feel for a gritty growl as it spins. Bearings in good condition are usually smooth and quite.
Try this YouTube video. **NOTE** Be VERY CAREFUL if you try the tests in the video.

https://www.youtube.com/watch?v=JRHj9_pwx7o

Sounds like worn rear gearbox bearing. It its manual , and bone mote than 120,000. Remove fuse to radio and see if it still makes the noise

Possibly a worn drive belt, or it needs tensioning.

The most common cause would be a defective power steering pump.

check he drive belts, spray with WD to see if it stops if so replace the belt.

The lost acceleration is of major concern. Maybe you have lost your water pump. It would work great for a few miles when you start out and then gradually heat up and loose performance. The fluid would eventually boil over? Maybe a bearing on the camshaft is expressing it's discontent and causing extra load for the engine to overcome. Try to determine where the noise is coming from.
The serpentine belt connects the alternator, water pump, power steering, front timing pulley, fan, and front timing pulley. All these components generate a parasitic load on your engine. If the engine has to work harder because of increased load it could be any of these components. I'd definitely check the water pump listening for noise while running. Look for obvious things related to the belt and its' components.
Check the serpentine belt for wear. May indicate pulley misalignment or wear. There exists two idler pulleys that have small bearings that wear out and squealing noises. Check those for wobble with the tension off the belt. They are pretty cheap so replace them if any concern at all.
Power steering pumps cavitate and make a high pitch gear whining sound if fluids are low or gears warn of. Check the fluid and top off to the correct level.
Best wishes,
TF

One or maybe both of the hubs have bearing problems. Lift the car and try to wiggle the tire holding the top and the bottom of the tire, If it moves its bad, It should be tight. The hub can still be bad if they are tight.

Lifting the car and running the engine in drive will not always help in hearing a noise because you take the load off of the tires. And its dangerous on jacks.

A power steering pump will whine if it is low on fluid, when you turn the wheels you will hear the whine or if the power steering belt is to tight you will also hear the whine. You will not hear this whine when the truck is stopped.

my 82 seca had an issue similar to this one. It turned out to be the tachometer cable. i would try lubeing it with some good lube. then go from there.