Nissan Problems

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.

This is actually a pretty common problem and there seems to be two common causes. The first is leaking seals inside the turbocharger. The turbo needs oil to lubricate it, but if its seals are leaking they can allow oil into the inlet tract and, therefore, the intercooler.

The second cause is possibly even more common and involves the crankcase ventilation system allowing oil into the intake (and intercooler). A modern engine needs to consume its own crankcase fumes and burn them (rather than vent them into the atmosphere) as part of its anti-pollution systems. But in many cars (and modern turbo-diesels are the prime suspects) those fumes can contain some oil mist which, once enough of it has accumulated, will form the oil droplets you’re seeing in the intercooler.

While a faulty turbocharger will need to be replaced, if the problem is the work of the crankcase ventilation system, it still should be addressed before the oil mixes with soot from the exhaust gas recirculation system (another emissions-control device) and forms a horrible, back gunk that clogs the engine’s intake system. If hat happens, costly disassembly and cleaning is required.

Even if you’ve caught this in the early stages (before the gunk can build up) the oil can still cause problems with sensors inside the inlet system and could cause poor running and high fuel consumption. A good quality oil catch can is the preferred method of stopping this occurring as it 'catches' the oil mist before it gets to the inlet tract.

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.

Bad news. That generation of X-Trail had a six-speed manual option on the base-model two-litre petrol, front-wheel-drive model and on the all-wheel-drive turbo-diesel. But if you wanted an X-Trail with an automatic gearbox, then it was a CVT or nothing.

This is probably because who ever serviced the car failed to manually switch off the service-engine reminder light. This is often done via a scan-tool through the diagnostic port.

But in the case of your car, you should be able to do it yourself. Turn on the ignition and you’ll see that the service light is illuminated. With the ignition still on (but the motor not running) press the small button that you’d normally twist to control the brightness of the dashboard lights. After a few seconds, the service light should start to flash. Release the button and then give it a single push (but don’t hold it). Now turn the ignition off. If you’ve got the sequence correct, the next time you turn on the ignition, the service reminder light should have disappeared.

You may have a damaged or worn transmission that is simply not operating properly in a mechanical sense. But it’s also worth checking the level of the transmission fluid because low fluid is a common cause of this sort of problem. Without sufficient fluid and, therefore pressure and volume, the gearbox can’t operate properly, with symptoms including slurred shifts, transmission slippage, clunky or noisy operation and slow gear selection.

The absolute best thing you can do now is get the car to an automatic transmission specialist. The shuddering could be caused by wear in the bands and clutches that control the gears or from damage or wear in some other part of the transmission or even somewhere in the rest of the driveline. It might even be a problem with the torque converter.

The fact that the level of fluid had dropped suggests a leak somewhere in the system that also needs to be fixed. But continuing to drive the vehicle in this state is likely to cause further damage.

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.

The correct way to proceed here is to have the car scanned to see if it will offer up what ails it. The on-board computer is designed to recognise a problem or fault, record it and then hand over that information to a mechanic during the scanning process.

You can try to diagnose the problem yourself, but doing so by replacing random parts is not the way to go. You can easily replace perfectly good – and expensive – parts and still have a car that won’t start.

But if you do want to tinker yourself, the first thing to check is the electric fuel pump. These require periodic replacement and when they fail, they just stop, and that’s it. To check the pump, turn the ignition to the start position and listen carefully for a buzz or humming noise coming from under the car. It can be difficult to hear, but if it’s present, then the fuel pump is probably not the problem. No buzzing or humming suggests the pump is the culprit.

Honestly, though, there are literally hundreds of reasons a car will turn over but not start.

It sounds very much like your car has a problem with what’s called its clockspring. This is an electrical contact that allows the functions controlled by, or mounted on, the steering wheel to operate while still allowing the wheel to be turned. Over time, the clockspring wears and finally breaks which is almost certainly why you lost the cruise control and horn functions at the same time. It’s also why the airbag light has illuminated, as the broken connector won’t allow the computer to talk to the airbag in the steering wheel.

Most workshops will be able to replace the clockspring, but unless you’re a competent mechanic, leave it to the experts as anything to do with an airbag requires utmost care and respect. Even the experts will disconnect the car’s battery before tackling any airbag issue.