tensioner or just pulley change, pleaase help

hi guys

i know theres heaps of threads on tensioner pullies but my issue is

i have just done
expansion tank
water pump
both pullies
new belt.

with the ideler tensioner pulley, i have a machanical one, i only un bolted the actual pulley and replaced with a new one, most of the noise went away but i still get noise from the front, like a light grinding squeeling.
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my question is when people change the tensioner, do they just change the pulley or the whole unit? if so would that sound be coming from the machanical tensioner unit itself? (considering i put a new pulley on the unit)

hope someone can help

thanks

zlat.

i think most change to the newer hydraulic one. perhaps the mechanical is no longer applying enough tension and the belt is slipping.