My old Kenmore sewing machine makes a loud squealing noise.

It sounds as if your machine needs a little oiling. If you have a clear machine oil (not 3 in 1). place a drop in the bobbin case area and if you will notice, you will see small holes on the bed and on the top of the machine. place a drop of oil into each of these holes. If you can take the top and bottom covers off, you can put a drop of oil every where you see a hole..some of the machines actually have the oil holes painted a red color. Also place a drop at the handwheel as well. Just remember when oiling, less is better. After oiling, run for a few minutes, if you feel it still needs a litte more, do the same, one drop at a time. After this, if you machine sets for a while, oil just before starting to sew, that way when you put the machine away the oil has been worked through and it should help prevent the squeaking when starting up again.