kernow580

I have recently brought a discovery td5 on a 52 plate with 112,000 on the clock, upon purchasing i was told that the injector seals had been replaced. after owning car for 1 week only the sump again filled with diesel so I had the seals re done. the car was then parked up for 3 weeks and then used for approx. 180 miles and guess what the sump filled with diesel again. I have been told that this could possibly be a cracked head or does anyone know of anything else that cause this? Also with the sump filling with diesel would this have damaged the bottom end? I am unsure whether to find and mend the fault or try and sell the vehicle...