Alternator question

[Parksy]

Just a quick question, why does the alternator have 2 pulleys and why is the outer pulley a smaller diameter than the inside one? I'm talking about a tb42e engine here in case it's unique to this engine. I've just replaced all the fanbelts and while I've got the inside alternator belt at correct tension, the outer belt is loose. Is this fine? Is it merely a spare if the inside one packs it in?

Cheers

Andy

[pearcey]

The pulley should be a double pulley with both V`s the same size and diameter

[NP99]

My 4.5 has a double pulley. Both belts need to be tensioned properly.

[threedogs]

X 2 with above , check with straight edge if aligned correctly

[Parksy]

So I take it the alternator pulleys are both supposed to be the same size then? Is it possible that I have the wrong one?

[pearcey]

Yes mate the pulley is one piece with two same size belt grooves.

[Lieney]

The previous owner may have modified it to accommodate something else, and only used one belt to drive the alternator.
If the alt has 2 groove pulley, the fan belts should be a matched pair

[Parksy]

Cheers guys. Will be getting a new alternator. Looking at them on eBay, they all appeared to have the same sized pulleys, hence why I asked the question.
I'm pretty sure my alternator is on the way out anyway, only putting out about 13.5volts and at start up I have to blip the throttle otherwise the battery light stays on.