Just because you can’t see where coolant is escaping, doesn’t mean it isn’t. Equally, a lack of milky oil in the sump does not guarantee that the problem is not a head gasket-related one. Even an external leak from a hose or fitting can be hard to track down as the hot coolant evaporates before you have time to find the witness mark or the coolant drips on the garage floor.

Your best bet is to have the car’s cooling system pressure tested. A mechanic will pressurise the system and leave it for a period of time. If the system holds pressure, that’s a good sign that there’s no leaking. If it loses pressure, you have a problem somewhere in the closed-loop cooling system. That could indicate a problem with a radiator, hose, water pump, head gasket or even a split bore or cracked cylinder head.

But there’s one other check to make that might save you a lot of time and hassle. Takle a close look at the car’s overflow tank. This is also called the expansion tank and is designed to catch coolant as it expands (through engine heat) before allowing that extra coolant to return to the engine as the car cools down at the end of the trip. If this tank is leaking (even from a tiny crack) coolant that expands into it will be lost and the cooling system will appear to be continually losing coolant.

Plenty of owners of this make and model have experienced similar frustrations with the rotary dial not selecting two- and four-wheel-drive promptly and accurately. It’s possibly down to a switch (the rotary dial itself) that has developed wear or play in its mechanism and simply isn’t as accurate as it once was. But it’s also worth checking the electronics that control the shift function, as a glitch might have the system trying to select something other than what’s showing on the dial.

This is a classic case of electronics taking over a mechanical function (early 4WDs had a simple, mechanical lever to switch between two and four-wheel-drive) and not being as good at it. This function, when you think about it, is an incredibly important one for this type of vehicle and might mean the difference between getting out of a bog-hole and not. Many owners would welcome the return of the purely mechanical lever, but that’s not the direction car design is travelling.

If neither the key nor the central locking will lock the hard-tonneau, it’s likely the latch is not engaging properly. Which in turn means you most likely have an alignment problem between the tonneau and the rest of the tray.

I’m not sure if you have the factory tonneau (probably) or an aftermarket one, but these are big, fibreglass panels that can sometimes shift a little on their hinges and fixing points, leading to the misalignment that won’t allow the latches to line up and engage.

The factory HSV tonneau for this car has a quick-release hinging system allowing it to be removed easily for carrying higher loads. Perhaps removing and refitting the tonneau via this feature will return everything to its correct alignment.