I also have not heard of timing chain issues with the diesels,I know timing belts on the petrols have to be changed at 120,000 k's,when I raised the issue a few times with Hyundai,I have been told that if the car has been serviced at the required intervals(including the optional services)the timing chains in the diesels very very rarely need attention,but on the ones that have had only the reqired warranty servioces,some have been required to be changed.(not many but)
After hearing this I did some hunting around to get some quotes,Hyundai being the most expensive at a tad under $1400,but found other mechanical shops which would do the same job for around $800