TomForrest

Sorry I should have been clear the crack (that is now a 10 cent hole, brittle stuff) is on top of the actual reservoir part of this plastic tank, not on the 'spout' to refill it, so it's around the same level as the max marker. My understanding is when the engine gets to operating temperature it pushes coolant into the reservoir due to a pressure increase. If I fill it to the max mark it will loose a fair amount on a short drive but then settles down to a much smaller loss, whether this is bubbling in the tank I don't know. The next time it starts to over heat I will pop the bonnet quickly before killing it to see if there is any 'bubbling' in the tank. Also very strange that the original leak at the back vanished to be followed by a much bigger problem? I really hope it's not a head gasket, I've checked for all the other signs and nothing. Oil is clean, engine has been running fine before the last couple of days (first real test it's had), a small amount of white vapour on start from cold but that's gone in a minute or so, and none when warmed up. The water shows no signs of oil mixing, I will definetly follow your advice and get a test to see if there is any mixing, it could just be a micro crack if there's now major signs but some symptoms? Unfortunately I'm a good 200km from the next town that might be able to help me, and in hilly conditions too! I'll make sure to post an update on whatever happens just so it's here as a reference. Cheers for advice I'll get the test done as soon as a reach a large enough town, along with having a really good look at the radiator cap (which I imagine I would hear hissing when the engine is over heating). Regards Tom Forrest

Thank you for your reply. Sorry my reply is a bit long winded but I just want to cover everything to try and narrow this down. I took it to a mechanic today, they couldn't see any sign of a leak at the back of the engine, suggested using a bandaid tablet to block any small leaks. Did as they suggested, heading out of town and 15km down the road it starts over heating, it had never done this before. I immediately stopped driving and pulled over, it had started leaking s lot of coolant from the reservoir, I found a small crack on top of the plastic tank, magic a new leak! I nursed it back to the mechanic when it was cool enough, they did a pressure test and found nothing, they also initially thought the fan may not be on its last legs but after a test they were happy it was still biting. We gave the radiator a clean out as it was a bit blocked up with leaves etc and he thought this was the problem. He said I would be fine to drive with a crack in the coolant reservoir (yeah skeptical about this) and sent me on my way. I headed off again and all seemed fine till I hit some hills, nothing major and no serious inclines, the car started over heating again, it would drop back down after the first 2-3 extended hills but after about 30 minutes it just stuck at 9:45 on the dial so I pulled over, it's worth mentioning it normally runs at 8:30-8:45. And here I am wondering what I can do next! It's not spewing out coolant anymore but I really don't want to cook my engine. Any thoughts? I know an older car will struggle up a hill but after the 2 days I've had I'm not taking any chances. Edit: just a quick addition from my email reply (figured I'd put it all here in case others can help) I've checked the oil and all good no 'mayonnaise' or foamyness. Regards Tom Forrest

Howdy fellow Pathfinder owners, As the title states I'm loosing coolant after long drives (2+ hours), I haven't seen any leaks whilst in the city, though apparently this could just be down to evaporation and 'pooling'. I only bought the old girl 3 weeks ago, and have kept my eye on the water and oil levels, it was only since heading out of town today that I noticed a drop, and a large one at that, she's always smelt a bit burny but I wasn't too concerned as temperatures were constant and there were no leaks. No worse than other cars I've owned that were fine. She blows a small bit of white smoke on colder mornings, but all fine once up to temperature. Though today after a long freeway drive the engine was still very hot 2 hours after parking up which was worrying. The problem is I'm meant to be heading across the country on a long trip, and can't afford to wait around for a week in some back water town while it gets fixed. From reading on here it looks like it might be worst case scenario and it's something that's a huge PITA/costly to fix, what's the best way of diagnosing the cause? I'm really stuck here as I need a working vehicle, but don't want to cause irreparable damage by driving it with an unknown leak. Any advice on what it might be would be amazing, cheers.