Source(s) of supply for new (used) motor

after changing the ZKD, the ignition plugs, coils, etc., the engine suddenly began to make like a tractor at 260 noises – as if it had no exhaust manifold or exhaust system. volvo just meant motor-total damage – something with camshafts, “you have to change the small engine (ha?), minimum”. however – can be repaired there nothing and a new motor will probably cost a fortune at volvo. On the other hand, it would be a pity to just leave the box standing after I “invested” a lot of gravel almost all summer long sooo. well, since I thought to myself, ask here – question is actually already above – where are there relatively cheap new, used, possibly repaired engines? is required a t5 or 2.5t…