I have a 2004 Toyota Altis. There is a loud screaching sound coming from the fanbelt. I changed the fanbelt and the sound stopped for a month and started up again. Belt dressing spray does NOT stop the noise. What do you suggest?

This can only be a loose belt. You need to adjust the tension (Usually done by loosening the altenator and pulling ot outwards before tightening it up again.

You may think it's tight enough, but tha fact is it probably isnt. Carefully undo the tensioning nut, slip a crow bar between the engine and altenator and lever the altenator outwards to a position further than ist is now.

Needless to say, careful where you put the crow bar on the engine and altenator and careful just how tight you make it. This is one of those "how tight do I make it....." "about until you give a little grunt and that's probably about right" moments.

Just tighten it a little more. Lock off the adjustment bolt, start the car and see if the squeal has gone. If yes, good job, if no, then go a little tighter.