Ask The Guide

Replacing random parts to fix a problem is a great way to tear up dollars and time. It’s also pretty frustrating when the problem doesn’t go away. The first thing to do is to have the car electronically scanned to see if the car’s own computer can point you towards the cause of the problem.

It may be as simple as the car needs a tune up and a new set of spark plugs, but you won’t know until it’s been properly diagnosed. This is not a complex car, so any good workshop should be able to sort it for you. The other problem, of course, is that the issue is intermittent, so it may take the workshop some time to be able to make the problem appear. Patience is the key here, not throwing a load of new parts at it.

These two readouts are closely linked in that one determines the other. Your average fuel consumption dictates the distance the car estimates it can travel based on what’s in the tank. But variation in these readings is perfectly normal. That’s because the range estimate is based on your most recent driving. So, if your fuel consumption has jumped from 7 to 8 litres per 100km, the computer will adjust the range down to compensate and prevent you from running out of petrol. That’s all very normal.

The bigger question is why your consumption has recently increased. Have you changed your driving style? Are you suddenly towing a trailer? Have you allowed another driver (with a heavier foot) to borrow the car? Are your tyre pressures correct? Have you added a roof rack? Do you now do more city and suburban driving than before? Is the car in need of a service and tune?

All these things can have a noticeable effect on fuel consumption, and any one of them could be the key to your fuel consumption increase and associated range reduction.

The trick to a diagnosis here might be to find out what rotational bits and pieces are involved. To do that, you need to work out whether the noise is wheel-speed related, driveshaft-related or engine and transmission-related. The driveshaft spins fastest, followed by the driveshafts and finally the wheels, axles and brakes. So that’s probably the key to it.

Even something as simple as a bent or loose brake shield can cause a rattle, squeak or grinding noise, and some owners have gone so far as to strap GoPro cameras under the car and take it for a drive to see what’s going on. A mechanical workshop will probably be a bit more scientific, but the basics of troubleshooting remain the same.

As far as the driveline locking for a moment, you could be looking at a related problem or a completely separate issue. It’s probably wise to make sure the transfer case isn’t suddenly shifting into neutral or low-range on its own for that split-second, as that could cause driveline chaos. But a sticking brake caliper or faulty ABS module could potentially also cause the same sensation.

Some cars cycle their ABS systems when you first start up and take off, and this can lead to a metallic noise for a second or two and a slight buzz through the car. It can be intermittent, too. Are you sure that’s not what you’re hearing?

The best place to start for some professional advice is a transmission specialist. They’ll probably inspect the transmission in your car and will be able to work out whether it can be fixed or if it needs to be replaced.

If you do need a replacement CVT, there are three main ways to go. You could buy a brand new replacement CVT which is likely to be the most expensive course of action. The second alternative is to have the transmission shop recondition the one you already have. This will also be quite expensive.

The third option is to find a good, tested second-hand CVT from a wrecked Koleos and have that fitted. This will be by far the cheapest way to go. But the gamble with option three is that the same problems might happen again, and you’d be back to square one.

I agree that a 2016 model-year car is too new to be thrown away, but failures of CVT transmissions are more common than they should be. It’s something car makers need to look at when they consider future designs and engineering.

If the problem occurred immediately after you replaced the carpet and seats, I’d say there’s a very good chance you’ve unclipped a wiring plug or connector to remove the interior, and failed to reconnect it afterwards. A lot of modern cars have airbags in the actual seat (the side airbag usually) and the wiring often runs under the seat.

The best move would be to remove the seats again and check for loose wiring or wiring or connectors that have been damaged of misplaced in the process of the interior’s removal. But before you touch anything under there, disconnect the car’s battery. That ensures you won’t have an accidental airbag deployment that could injure you while you’re working in that space.

This sounds awfully like badly worn transmission. The Dualis in automatic form used what’s called a CVT. Instead of gears inside the transmission, the CVT has pulleys and metal belts that vary their relationship and, therefore, create the various 'gear ratios' the car needs.

When these pulleys and belts wear, they can start to make the noise you’re reporting. And, just like your car, it will get noisier as time passes. Unfortunately, you’re probably looking at a transmission overhaul or rebuild. If you continue to drive it as it is, you’ll almost certainly do more damage, although it sounds like the real damage is already done.

Take the car to a transmission specialist who will be able to accurately diagnose the noise and take it from there.

The problem of the sump filling with diesel was not unknown on early CX-5 diesels. A leaking injector is possible, but the main cause of this was believed to be the car’s DPF regeneration process dumping large amounts of fuel into the engine, some of which finds its way past the piston rings and into the sump. Either way, a new engine is a large expense.

There’s every chance that Mazda won’t offer any help given the age of the vehicle, nor is this type of engine damage usually a cause for an insurance claim. It would definitely be worth contacting Mazda Australia’s customer service division, but don’t hold your breath.

It’s true, there’s not a lot of weight saving with a smaller spare wheel and tyre, but these are called space savers, not weight savers. And that’s because they’re about saving space in the luggage compartment first and foremost. Many modern cars with huge wheels and tyres could not swallow a full sized spare; there just isn’t space inside the vehicle. So, the space saver was the industry solution.

They have obvious limitations, too, including the limits on distance and speed you can travel on them. And you would not be the first or last owner to replace the space saver with a full sized spare. In rural and remote areas, a full sized spare is great peace of mind.

It sounds like the transmission has broken something internally. It could be that the clutch assembly is smashed, or the input or output shafts have snapped. It could even be the actual gearsets that have failed, leaving you with no mechanical connection between the engine and the gearbox.

Either way, it sounds like it needs a new clutch and/or gearbox which may be more than the market value of the car. That said, wrecking yards are full of Hyundai Getzes, so a second-hand, tested transmission might save the day.

While the ZD30 engine should have been a major step forward in terms of technology with common-rail technology and double overhead camshafts, in reality, the engine was not one of Nissan’s finest moments. Bottom end failures were not uncommon with cracked pistons necessitating full rebuilds.

Several causes have been suggested including poor fuel-air ratio management and boost spikes form the turbocharger putting sudden, huge loads on the engine’s internals. Either way, though, the engine is far from remembered fondly.

CarsGuide has looked at this engine in depth, and even published a guide to the Nissan Patrol ZD30 engine.