Looks like the friend was correct. Returned from a day trip. It started a few minutes later. Released the fuel cap and didn't happen again. Booked a service in two weeks so will see what they say. Hope others will benifit from this thread. And thanks Manning for contributing.
OK a friend of a friend who is into Navara's said the same. When the fuel tank empties or gets low the air pressure does not equalise in the tank and a pump is trying to stabalize the air pressure. He said to just unscrew the filler cap. Going to try that tonight.
No rust prevention unit that I'm aware of. The noise is coming from sort of under the engine bay not from inside. Its very consistant on the hour. I'm wondering if its heat related. It sounds like a motor running. I'm off to see a local dealership. Thanks again for your thoughts.
Hello,
This is probalby posted before but I can't find a similar post. As background I'm a non tech person. I have a 2018 Nissan Navara STX, done 75,000k's. Currently doing a camping trip around Australia and have just noticed that the engine quietly hums for about 10 seconds every 30 minutes...