hello. I have just recently brought a Nissan patrol gu 1999 st 4.2l diesel. I have seen 2 different mechanics and been told different things. the engine runs on after keys turned off. petrol it would be timing but diesel I don't know. I have some knowledge of petrol engines but as this is my first diesel and first 4x4 I don't know a lot. (still learning). so I think they were trying to take advantage of that and make me spend big bucks when only a small problem. if someone could help with this would be much appreciated. Thanks Aaron.