Short lived front engine clunk - and rubber debris found

[ontheway]

Hi all

Started my 2013 SDV6 L320 yesterday and there was a rotational "clank" coming from the front of the engine. It was quite distinct, somewhat metallic, not overly loud and consistently timed and felt like it was at the frequency of the front belt but I didn't have time to check at different RPM. Then it suddenly went away.

I had a quick look at the front belt - but really couldn't discern anything mainly as I probably couldn't see.

Then the next day, possibly by coincidence, I found a 35 cm long length of rubber that looks like it has been mechanically stripped off something. It was located directly below the engine when the clunk stopped. Checked the tyres as the ground was not flat but no match. Neither of the surfaces feel like the main front belt. There are three distinctive round bumps equally spaced shown in the last photo.

Interested in any obvious suggestions??? Photos below.

Thanks

P.S. Car has done 145k - front timing, rear pump belts have been changed (assume they are enclosed?). Have to admit I haven't paid attention to the accessory belt(s) and assume they were changed but maybe not. Car gets 10k services.



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[DieselDan]

Rubber from the harmonic balancer maybe??

[loanrangie]

Rubber from the harmonic balancer maybe??

Nah way to big for that, not from the serp belt either unless its delaminated from the top section but it would be very noticeable if it was.

[ontheway]

I might have to go back the obvious answers - aircraft tyre or de-orbited space junk.

[veebs]

Looks like a bit of truck retread you picked up at some point?

[Eric SDV6SE]

Def not aux serpentine belt, they are heavily corded, flat and ribbed. All pulleys are steel and ribbed, tensioners are flat, and it's too much rubber for the hb. Timing belt is encased, and engine won't run if that goes (new engine or heads at least in that case) Only thing I can think off is you've picked something up from the road that has somehow gotten caught up in the engine. I am assuming the car ran fine after the 'clank' and before finding the rubber strip? I has a strip of soft foam sitting between the top of the radiator and chassis top cross over, that came out once and the fan chopped some of it up, but there's nothing like that rubber strip on the frontvof the car or in the engine bay.