Aux Belt

[leestudd30]

I don't mean to sound thick but what does the aux belt do on an HDi 90? Just had my Picasso in for an oil change this morning and they've advised me the aux belt has perished, clearly still working though. I'm assuming its something to do with the alternator/air con? Never had one changed or fail on any of my cars before!

[gumby6371]

It's the drive belt that runs to the alternator, PS pump and AC if fitted, sits on the drivers side of the engine for UK. Cheap to replace and a straight forward DIY job. If you do the idlers and tensioner it's a little more involved but still very doable on your driveway with minimal tools.
A reasonable selection of sockets and spanners, jack and an axle stand, torx bit for the wheel arch liner and a 3rd hand to hold the tensioner while you fit the new belt. Most important bits are a pen and paper to draw the belts original route to save scratching your head when fitting the new one
the tensioners can normally be 'locked' to release the tension but I don't normally bother and get someone to hold it open with a spanner.

If you just change the belt it can be done with just a long spanner on the tensioner to give you enough slack but if the idler and tensioner feel rough to turn by hand or loose and funds allow do the lot. They have been known to let go and take the cam belt out so well worth changing if it's old or tired looking.

[Doggy]

A minor word of caution, it's fairly easy on a 406, but was FAR more awkward on my old HDi 90 Xsara as the engine's much nearer the inner wing. Not being a body builder, I can't get enough leverage to release the spring on the tensioner without using a 2nd spanner for additional oomph.

Trouble is there really wasn't enough space to do this on the Xsara and I wound up rounding off the hex on the tensioner.

[teamster1975]

Here Lee