You should figure $2000-4000 for repairs. New timing chain, valves, and camshaft at the least. Worst case is $4000-5000 for a complete engine rebuild. Timing chains don't fail often unless the engine is neglected.

I can see you don't know much about the diesel's. Your best bet is to skip the car altogether and find a good, running one.

There is no 85 SDL or 117, BTW.