Fan belt help

[Sparkles]

Looking for a bit of help

My fan belt snapped on my 2006 C320 CDI midway along the motorway the other day, after fighting with merc over parts for a few hours I finally got it all sorted and had my mechanic fit it, today (after only covering 50miles since fitting new part) it has snapped again.

All pulleys are working fine and to the sight there are no obvious reasons for it being shredded so quickly . . . Anyone have any ideas? Really reluctant to keep buying parts that don't last 24 hours :-(

Thanks in advance x

Sparkles x

 

[Frontstep]

Its unlikely to be a belt fault more likely a bearing,pulley or alignment fault.
You need it checked properly before fitting another.

 

[television]

This will probably be the one way clutch that has failed on the alternator, it can be changed in situ

 

[Pathfinder]

Definately a pulley wheel alignment problem.