So I have had a squeak coming from around the area of the AUX belt for the past few weeks. It's gradually got worse. Sounded like the aux belt as that is the first thing that's springs to mind. The AUX belt has been changed and still it's squeaking, nowhere near as bad but still there. The squeak disappears when the engine gets hot. 

 

Anyone got any ideas or suggestions on what to look at next. 

 

Thank you in advance. 

The alternator pulley usually has a one-way clutch built in to it, which is why it's so deep.  When they fail (they lock up) the aux belt ends up flapping a bit as a 'standing-wave' occurs and the belt gets stressed - your new belt might take this abuse with less noise as it grips the pulley wheel better (?).  The clutch is there to smooth out drive pulses from the engine.  If the belt is removed (which is quite a quick and simple task) you could check the alternator pulley to see if it 'overruns' properly when you spin it with your hand and stop it suddenly.

 

I reckon the failure is through the installed grease drying out and hardening, maybe heat softens this, so it becomes quieter when the engine is hot.

I've never seen one fail, but 120,000 miles is typical I read somewhere.  A special tool is needed to remove it from the alternator, but it's not too expensive.

The part is an SKF or INA brand item, usually. 

 

Just a thought...

Edited 14 November, 20178 yr by CombatWombat