Spannrollen 1Z: Tension Springs, 1Z Type

Hello,

Even though the question might sound silly, how many tension rollers does a 1Z have?
In my opinion, there are 2 belts: a timing belt and a serpentine belt (for the alternator), or am I wrong?
I'm dealing with a warranty issue. The invoice lists two tensioner pulleys, but the workshop claims that the tensioner pulley for the alternator belt wasn't replaced. After the timing belt replacement, which also included the serpentine belt, I've been experiencing a humming noise whenever the alternator is under load, which seems to be coming from the tensioner pulley. (I believe they only replaced the tensioner pulley for the serpentine belt, but not the spring element.)

Thank you.

Okay, so after I managed to convince the mechanics that the tensioner pulley listed on the invoice was for the serpentine belt, it was replaced without any problems.

Today, the mechanic tried to pinpoint a different noise, a kind of rattling sound. He thought it might be the intermediate shaft, which drives the vacuum pump. He said the gears were probably worn, and that would be causing the rattling. However, he claimed it wasn't a major issue and could be lived with. He noticed it because the noise gets louder when the brake pedal is pressed.
What do you think about that?