Foreign Object Damage

Foreign Object Damage
Is it really essential to thoroughly clean manifolds and piping? 

We recently reconditioned a customer’s own 2 Litre Saab 9-3  Turbo engine, the engine was then returned to the customer’s garage for fitting.

The engine was fitted to the vehicle and started and run in the workshop without a problem, on the subsequent road test the mechanic reported a loud rattling noise from the top end of the engine. 

We recovered the car from just outside London to our workshop in Doncaster.
The spark plugs were removed and a quick look inside confirmed that there was damage on 2 of the pistons. 
The cylinder head was removed and it was apparent that the piston damage had been caused by foreign objects of some kind
The cylinder head face had also suffered similar damage. 
We recovered 2 small pieces of metal that were easily recognised as parts of a valve – all the valves in the cylinder head were intact meaning the debris had been ingested by the engine.
All in all it was a very expensive bill to repair damage that was easily avoidable.
To make it worse we actually put a large warning notice on the top of the engine before delivery stating; the original engine had suffered a catastrophic mechanical failure and the manifolds must be thoroughly cleaned before the reconditioned engine was fitted.