Kenmore washer 600 series is making a loud noise when washing and really lound when draining. Still works just lound noise maybe a little bit of grinding when washing.

SOURCE: Kenmore 80 series top loading washer won't agitate and is noisy

Sounds like u may have broken the coupler gear between the motor and transmission... the replaced the belt with these gears on this model... But should go fill & pumb water out and NOT spin Or agitate... IF these gears or broke or stripped... heavy loads like u  said would do this... recheck and see if wash will pumb water out But will NOT agitate or spin.. IF so the above is your problem  and is Not to hard to repair  or much money

Below is a pic with the motor remove the white piece in the middle is 1/2 of the gear system with a rubber piece in the middle (not there)  and another like gear on the motor
sounds like these gears may be broken or stripped on your washer

SOURCE: loud noise while agitating in wash cycle

I have the same problem, loud plastic squeak/grind when agitating only. I'd like to fix it, but have never taken apart a washing machine.

The advice below sounds good but where do you start with "begin dissassembly from the tub down"....etc. Anyone have a good internet resource with images for disassembling this machine?

Thanks.

SOURCE: Kenmore 80 Series Top Load Washer not agitating

Check out this you tube. Had the same problem today. Tipped washer on its side and replaced coupler between motor and gearbox. Parts are about $15
This is a good diagnosis video.
http://www.youtube.com/watch?v=VYOP0_KCYT0

SOURCE: Kenmore 80 series 110 washer making loud noise during final spin

Make sure all springs are still in their place tilt the machine back and look under it and you can see them. 2nd all legs must be level as well as the floor.

SOURCE: Kenmore 80 Series washer will not spin; MOD#110-22882101

you need to replace the motor coupler between the motor and the trans.,let me know if you need more help,mike