As far as timing belts are concerned there are two sorts of engine, the interference engine which is likely to suffer damage and the non-interference engine which is quite safe. The latter type is rare and almost exclusively the earlier designs of timing belt engines.
The type and degree of damage varies somewhat depending on the design of the engine. In nearly all cases the cylinder head must be removed and at least a few valves replaced. I believe almost the worst was writing off a cylinder head and the camshaft was broken into five pieces. The worst was where a valve head broke off and rattled around enough to write off the cylinder head and badly score the bore before dropping through a hole in the piston only to rattle around in the bottom and then arrive back in the top of the engine through a different piston.
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As far as timing belts are concerned there are two sorts of engine, the interference engine which is likely to suffer damage and the non-interference engine which is quite safe. The latter type is rare and almost exclusively the earlier designs of timing belt engines.
The type and degree of damage varies somewhat depending on the design of the engine. In nearly all cases the cylinder head must be removed and at least a few valves replaced.
I believe almost the worst was writing off a cylinder head and the camshaft was broken into five pieces. The worst was where a valve head broke off and rattled around enough to write off the cylinder head and badly score the bore before dropping through a hole in the piston only to rattle around in the bottom and then arrive back in the top of the engine through a different piston.