Nissan Problems

Actually, this is simply how a CVT operates. When you load the engine (and towing a caravan is a great way to do that) the transmission will switch to a lower ratio in order to keep the engine in its comfort zone and making enough power to keep everything moving at the speed at which you’ve set the cruise control. Because there are no set ratios in a CVT, this can sound a feel very alien when it happens. It's one of the things many people dislike about CVTs.

When you turn off the cruise control and allow the throttle to return to idle, the car detects that the crisis is over and changes the ratio to allow the engine to slow down as less power is needed. And that’s why it all feels like it’s returning to normal. But, really, what you’re hearing and feeling is just the CVT doing its thing.

You could be looking at something internally wrong with the transmission, but the clue that this might be something simpler is in the way the engine will start in Reverse which, of course, it shouldn’t (for safety reasons). The suspicion would be that the relationship between the selector (inside the cabin) and the actual gearbox is somehow out of synch. So when the selector is telling you the car is in Reverse, it’s actually in Park or Neutral, which is why the engine will start.

That might also explain why the car won’t select fourth gear; the position that actually coincides with Drive (or fourth gear) looks – from inside the cabin – to be the Neutral position. So, to check this, put the car in what looks like Neutral and, in a safe place, see if it moves when you give it some throttle.

Failing that, you’ve got two separate problems. The first is the inability to select fourth gear (which could be a hundred things) and a failure of the safety switch which is allowing the engine to start in Reverse.

This goes against everything we were told a generation ago about the transmission fluid in automatic gearboxes. In the old days, bits of clutch and metallic band would wear off the internal parts of the transmission, requiring the fluid to be changed to avoid this dross doing damage to the actual transmission.

The theory is that with today’s better transmission designs, materials and precision engineering, this is not going to happen and the vehicle can use the same transmission fluid for its entire operational life. Maybe it can, maybe it can’t, but I’m with you in being a bit confused about it all. My preferences (and that of many transmission specialists) is that even in a sealed-for-life transmissions, you won’t be doing any harm by replacing the fluid at sensible intervals. And if you do happen to flush out some rubbish in the process, the expense might be well worth it.

Bear in mind there are two types of fluid change. The cheapest is simply a case of emptying the transmission’s pan and adding enough new fluid to take the level back to where it should be. The second, more expensive, option is what’s called a flush. In this case, the fluid in the gearbox is changed, as well as all the fluid in the lines, coolers and other plumbing around the car.

The only catch with this would be if Nissan regards a fluid change as some kind of tampering and takes the view that this would void any factory warranty. So check with Nissan first. The correct type of fluid for your car’s CVT is also crucial.

Because the Elgrand was not officially imported into Australia by Nissan, parts can be a bit difficult to obtain. Mechanical bits are not such a problem as the Elgrand used mostly Nissan Maxima or Altima mechanical parts. But body panels and trim pieces can be more difficult to obtain.

That said, there are specialist parts recyclers that deal in these vehicles. A quick internet search might turn up what you’re after or at least give you a few clues on where to look next. The companies that import these vehicles for sale here also sometimes import spares parts as well, so they’d be worth a call, too. While not terribly thick on the ground here, the Elgrand is popular enough that there will be a part supply industry that has built up around it.

This sounds more like a control problem that one with the actual compressor. The body computer is often at fault in cases like this. Part of the body computer’s job is to control things like central locking, power windows and the climate control gear. The fact that the system is cycling between fresh air and recycled air makes us suspect the computer as the culprit. Has this been checked?

Hopefully, you first raised this issue with Nissan all those years ago when the vehicle was still under warranty. If so, then you have what is called a pre-existing condition and even though the car is now out of warranty, Nissan is still obliged to fix it as if the warranty still applied.

There's often a disparity between what a car is insured for and what it might be worth on the second-hand market. In any case, with a worn out engine, its market value would be next to nothing anyway. And with 290,000km on its odometer, you might have trouble finding a buyer willing to take a punt.

That said, even if you put a low-kilometre second-hand engine in it, the fact remains that everything else from the transmission to the wheel bearings, brakes and suspension have also done 290,000km and can be pretty much guaranteed to be fairly worn themselves. You could then find yourself shelling out more money every year to keep the car running on the basis that you'd already spent $10,0000 on a replacement engine. Sometimes it's better to cut your losses and buy something newer.

This model X-Trail is fitted with active lane-keeping assistance which is sort of a helping hand when the driver isn’t keeping the car in the centre of its lane. It could be that this system is what’s causing the car to feel like it wants to pull you into the next lane.

You need to have this checked under warranty as soon as possible, since it’s an obvious safety issue. This isn’t just a Nissan thing, either. Many brands have had complaints about these systems, and in some cases, cars fitted with collision-avoidance systems have been known to slam on the brakes when the car’s camera 'sees' something like a wheelie-bin on the footpath and mistakes it for a truck entering the road. Speaking of which, your lane-keeping assistance is controlled by a camera at the front of the car. Have a quick check to make sure there’s not a huge dead bug confusing the camera.

You could be dealing with either a worn transmission itself (where wear inside the gearsets, shafts or torque converter has made something sloppy) or there’s something else in the driveline (such as a differential or universal joint) that has likewise allowed some looseness or play to enter the equation. In either of those cases, a thump or clunk during shifts can be a symptom. It feels worse under acceleration, as that’s when the maximum stress is on all those moving, meshing parts.

Sometimes, a transmission can be serviced and adjusted to get rid of thumping or banging during shifts. Take the car to a transmission specialist who will be familiar with this transmission and may be able to return it to civility.

This model X-Trail used a conventional automatic transmission with a torque converter. There are lots of things that can cause this condition, including a failure of the torque converter or any number of moving parts within the transmission itself.

But the first check is to see if there's sufficient transmission fluid inside the gearbox. Use the transmission dipstick to check the fluid level according to the owner's manual's instructions. A transmission with low fluid can certainly exhibit the symptoms you've noted. A quick fluid top up might put the wheels back in motion.

Bear in mind, however, that the transmission is a sealed unit and should only require top ups if there's a leak somewhere. That leak needs to be identified and fixed or the problem will recur.