Noises are impossible to diagnose without actually hearing them. So you need to take the vehicle to a mechanic and get the car to produce the noise you’re reporting. That may involve leaving it overnight or otherwise reproducing the circumstances under which it misbehaves. Experienced mechanics can often tell whether a noise is important or just wear and tear, and act accordingly.

For the record, your mystery noise could be anything from a worn turbocharger, a sticking hydraulic lifter, piston slap, bearing knock or even something as weird as a loose baffle in the exhaust system. All these things can manifest as random and metallic noises, and they range from simple to catastrophic in magnitude.

As second-hand buys go, the Holden Captiva is a no-go zone. These were not reliable cars when they were new and the years and kilometres since have only made that situation worse. The V6 petrol engine is prone to stretched timing chains which is a huge and expensive job to fix and the automatic transmission is also a turkey. The Captiva was also home to many an oil leak and electrical problems are common.

These are now cheap cars, but for a very good reason. But even a car that is cheap to buy can wind up costing you lots if you need to constantly repair it. There are plenty of far better alternatives.

It sounds like the entire car is shutting down. And if that happens at speed, or just as you’re preparing to pull out into moving traffic, that’s an incredibly dangerous thing to be happening. The best advice is to have the car scanned electronically, at which point the real problem might raise its head.

Beyond that, you’re clutching at straws, because whatever is going on is a fairly serious problem. Scanning the on-board computer doesn’t take long, and diagnosing the problem this way will save you time and money in the long run. It might even save you from a crash.