Ask The Guide

I’m afraid to say, David, that it sounds like you’ve prematurely ended the engine’s life. I’d say a blown head gasket is just the beginning of your woes here, and it’s likely you’ve `cooked’ the engine; a mechanic’s description for getting the engine so hot inside that the piston rings have lost tension (hence no compression) or parts of the engine have even melted internally, with obvious results. It’s also common for this type of thing to have the engine more or less weld itself together, at which point it won’t even turn over on the starter motor.

You might be lucky and simply have to replace the head gasket, but even then, you’d be wise to have the cylinder head checked for straightness. If the cylinder head is warped (as a result of the heat) then you might need a new one, at which point you might find the cost of repairs suddenly goes beyond the actual value of a 2006 X-Trail. The moral of the story is to keep an eye on the temperature gauge and not to ignore the first signs of the engine beginning to run hot. Pulling up to add water after the thing has overheated is a classic case of shutting the gate after the horse has bolted.

If you do wish to keep the car, my advice would be - once you’ve established the extent of the carnage - to find a good second-hand engine from a wrecked X-Trail and have that fitted. It would almost certainly be the cheaper option in the long run.

I assume you mean it’s higher than normal, because these were thirsty trucks to begin with. The 4.8-litre petrol six-cylinder engine could easily consume 20 litres per 100km at freeway speeds and a lot more around town or in the bush. Even the turbo-diesels were no sippers.

But a sudden jump in fuel consumption can often be traced back to either tuning or a glitch in part of the fuelling system. Make sure the car is serviced and has a clean air filter and new spark plugs (if it’s a petrol engine). You can also have the fuel-injection system checked to make sure you don’t have a stuck injector that is pouring fuel into the engine when it doesn’t need it.

If the engine is fit and healthy, you can then make sure the car doesn’t have a dragging brake or another mechanical problem that is – literally – dragging it down. Don’t ignore the other basics, either; under-inflated tyres can also cause high fuel consumption. And, have you fitted a roof rack lately? These can easily add a full litre per 100km to your overall consumption figures, just through wind-drag.

The most common cause of this type of problem is a worn oil pump in the transmission. An automatic works on hydraulic pressure and if the pump is worn, it often can’t muster the necessary pressure to effect a gearshift when it’s cold. Once it’s warmed up, everything moves a bit more freely and the car will select Reverse. The fact that there’s still a gear-selection delay even when warmed up is the giveaway that this is the case.

If you continue to drive it like this, it will possibly go for some months. But you need to be aware that the faulty oil pump is not only making shifting difficult, it’s also potentially starving the bearings of the lubrication they need. The end is nigh, I’m afraid. You could take a punt and have the gearbox serviced with new fluid and a clean filter, but, on balance, the pump is likely to be the culprit and is also indicative of general transmission wear and tear

Good news, Amy; your Corolla has an engine with a timing chain rather than a timing belt. While a timing belt needs periodic replacement, the timing chain should be good for the life of the engine.

Sometimes, the codes spat out by the on-board computer can be quite vague. But this isn’t one of them; in fact, it’s quite specific. Checking the code against the translation reveals that code 0705 refers to a faulty signal from the transmission-range sensor. This sensor sends information to the engine and/or transmission control module and is responsible for those computer modules knowing what the driver is asking for via the gear selector. Without a correct Park or Neutral signal from the transmission-range sensor, the engine won’t crank and start. Beyond that, the gearbox may select the incorrect gear thanks to the incorrect signal being sent. Replacing the range sensor is probably the fix you need to look at.

It seems like the fix here would be an obvious one, but there’s a number of potential causes for a fault like this. Let’s start with the actual starter button. It could have failed internally. Or the starter motor itself might have either failed or simply had a critical wire fall off its terminal. Perhaps the immobiliser system is not arming the ignition as it should.

And here’s one from left field: Is the transmission in Park? If it is and the engine still won’t turn over, try putting the selector into Neutral. Both Park and Neutral should allow the engine to start, but most people only ever try it in Park. You could also have a poor earth or iffy battery terminal which is allowing enough current to pass to illuminate the dashboard lights, but not enough to actually crank the engine over.

If the engine runs when you apply some throttle but won’t idle, I’d be drawn to the idle stepper-motor which is a small electronic actuator that is designed to keep the engine at a stable, steady idle when no throttle is applied. It’s a pretty simple fix, but I’d also check things such as fuel delivery pressure and ensure that the ignition system is in good condition, also. Don’t forget air and fuel filters, either, they’re simple things but critical to how an engine behaves. Low battery voltage can also make an engine like the Challenger’s play up at idle, too. Also, have the throttle-position sensor checked. If this fails, it can leave the computer guessing about what the accelerator pedal is trying to tell it.

When your specialist says the water pump is sweating, he or she is referring to a tiny amount of coolant appearing on the pump either where it joins the rest of the car’s cooling system or through the pump seal. You won’t see a drop in the coolant level because the leak is so tiny, but neglected it could eventually develop into a leak that will need immediate attention. Better to sort it now rather than wait for it to become a problem.

Given the mileage you’ve quoted, I’d imagine the car is relatively new and is still covered by the VW factory warranty. That’s why your mechanic has flagged it rather than fixed it; because it’s a warranty issue and should be treated as such by the VW dealer and fixed for free. I can understand why the dealer would rather ignore the problem; they don’t want the hassle of fixing it when it might not become an issue for many thousands more kilometres. You need to get your specialist to confirm the issue in writing and then contact VW Australia’s customer service department and discuss the issue if the dealer still won’t play ball

I have heard of Volkswagen engines that needed replacement coolant pumps early in life, so definitely don’t ignore it. A pressure test of the cooling system may provide further proof that there’s a problem.

The most likely answer is that the body computer on your car has a problem. This computer is the one that links all the various functions (and the driveline) to each other, including cruise-control, the instrumentation, lighting, power-windows and, of course, the central-locking.

If the problem is deep within the computer’s circuit-board, you may need to swap it for a new one. But before you spend any money, try this: Close all the doors and then hold the lock button down on the remote. Hold it for at least 30 seconds and then see if the central-locking is behaving. If that fails, try disconnecting the battery and leaving the car for at least an hour. What you’re trying to do is manually force the body computer to re-set itself. This process doesn’t work with all cars, but it does on some and who knows, you might just be lucky.

If it’s the front indicator globe that’s blown, you need to open the bonnet and work from inside the engine bay. The front indicator globe is held in a plastic component that forms part of the whole headlight assembly. The bit you need to find is right at the outer edge of the headlight assembly, right in the corner of the engine bay. Once you’ve located that (it will have wires coming out of it), a half clockwise twist will allow you to remove the plastic globe holder and change the globe.

If it’s a rear globe, you need to open the hatchback, remove the screws that secure the tail-light assembly and then slide the tail-light free of the car. Turning it over, you’ll see the wiring and some plastic clips that fasten the globe-holder to the whole assembly. By unclipping this holder, you can remove it from the rest of the tail-light and reveal the globes which can then be removed and replaced.