Aux belt shredded

[Uzayr Jadwat]

I was driving around 100 to 110km/h on the motorway when I suddenly heard a strange noise coming from the engine followed by the sound of something loose rattling around the engine bay. The cars revs jumped a little then all the engine lights came on and then switched off. I pulled off to the side and tried turning it over with no success....had to get towed to the mechanic. The mechanic had a look and saw that the aux belt had stripped causing the timing belt to seize up which caused the cams to jump timing which in turn probably bent some valves. The aux belt was in good condition according to the mechanic so the mechanic claims a stone or some debry had to get caught in it to cause it to shred. There is no sign of any of this. Because it wasn't a part failure apparently insurance doesn't cover it. Is there anything else that could've been the source of this problem? I refuse to believe a random stone can cause this as this car is apparently 'track focused'. If I could somehow point the blame at a failed component instead of a stone causing a the belt to strips this could easily save me around 1200 euros

 

[Sean197]

Stones/debris can absolutely cause the aux belt to come off, which in turn can take the timing belt with it. Both Pure Motorsport and AP Motorsport sell covers to protect against this.
Unfortunately unless you can prove a parts failure (tensioner etc) then I'm afraid you're left with the bill.

 

[Uzayr Jadwat]

Stones/debris can absolutely cause the aux belt to come off, which in turn can take the timing belt with it. Both Pure Motorsport and AP Motorsport sell covers to protect against this.
Unfortunately unless you can prove a parts failure (tensioner etc) then I'm afraid you're left with the bill.

For a little more context I had the timing belt changed in March by the same mechanic and have only done maybe 300 to 500kms since then. Could the mechanic not have installed the aux belt back properly or didn't tighten the timing belt back properly? I've seen forums where this happened and the shop fixed the damage free of charge but how do I say it could've been their fault because so far they're still blaming a rock with no evidence

 

[RSRowe]

Anything is possible, but the likelihood of the aux belt not being fitted correctly are very slim.
If something is loose on the timing side, that would be pretty evident as soon as you took it apart. It would be useful to check to see if the tensioner has been adjusted correctly too.

What are you hoping to achieve out of all this? If you are worried about the honesty of the current garage, cut your loses and go elsewhere.

 

[Frank Perry]

Do you have the engine under-covers fitted (or at least, were they in place) when the belt got shredded?

If not then it'll be tough to point the finger!