Hi guys, we have an 04 3L diesel patrol and it has been running low on power getting up hills for about the past 8 months. We were told it was probably the filters at first which we had changed. The car has always been serviced religiously at every 7-9000kms as it is out work truck we keep up to date with everything. So long story short, it started making a dripping noise every time you turned the car off (this was straight after a coolant flush they did). After this, it overheated once about 4000 kms into the time after the service and coolant flush. There was never any drip marks or any evidence of a leak anywhere. Took it back to mechanic after overheating to which they did another coolant flush and straight after that we went to out first job about 5 kms from mechanics and it spat coolant everywhere and from them on has been gurgling like crazy!! The gurgling is definately coming from coolant tank too. We took it straight back to mechanic and they basically had no idea and told us to trade it in.. So we have taken it to another mechanic who said it could be an air lock which is what we were hoping for but unfortunately it is not. So it's either (from what I am told) the head, the block or the gasket. I am thinking of putting a 4.2 engine into it rather than buying a new car as we have put a lot into this. I have heard the big symptom of a cracked head is blowing white smoke which our car doesn't ever blow any smoke at all. Just wondering if anyone has any ideas at all before we go ahead and spend money on this. Thanks all!