Did road repairs cause my Citroen C4's alternator drive belt to break up?

My car, a Citroen C4 1.6 HDI, broke down with a very loud cracking noise from under the bonnet. The franchised dealer found the alternator drive belt was breaking up due to road grit ingress and the noise was due to a strand from the disintegrating belt slapping other components. They showed me a picture they took of a sizeable quantity of road grit found on the engine undertray and embedded in the belt. An A-road near here had been resurfaced recently with grit on tar. I had to pay the repair bill myself, not a massive sum, but the car is under guarantee and I maintain that inadequate screening, that allows road grit to get to an auxiliary belt, is a design fault. This is typical of Citroen's reputation for customer goodwill. Have you any thoughts on this episode and heard of this type of fault before?

Asked on 21 September 2013 by KS, via email

Answered by Honest John
You were very lucky, because if that aux belt had come off and wrapped itself into the timing belt, your engine would have been wrecked. But this is a sensible warning to drivers to check their engines for grit after driving over this cheap and nasty method of road repair that seems to be all the country can afford these days.
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