Ask The Guide

Some markets have indeed experienced problems with the Nissan CVT transmission as fitted to many of the brand’s vehicles. It doesn’t seem as widespread in Australia, but some faults have been identified.

That main problems seem to be overheated CVTs which can cause juddering when driving and premature wear inside the transmission. According to some in the trade, the fault is caused by a problem with the way the transmission fluid is cooled, and when it gets too hot it can cause warping of the metal parts inside the unit.

Ultimately, the solution would be to fit an external oil cooler for the transmission fluid, but otherwise, a close eye on the level of transmission fluid and correct servicing is the key to making the CVT last.

I’d say that you’re absolutely spot on that the rising level on your engine’s dipstick is caused by diesel getting into the sump. At this point, you have a problem because the diesel will be diluting the engine oil, meaning it won’t be lubricating the engine parts as well as it should. Leave it unchecked and eventually you’ll damage the engine internally.

There are a couple of major ways for this dilution to occur. Firstly, a worn, damaged or stuck fuel injector can dump excess fuel into the engine. At this point, the engine can’t burn it all, and some finds its way past the piston rings and into the engine’s sump.

The other common way for this to happen is when the vehicle’s Diesel Particulate Filter (DPF) becomes full of soot and needs to regenerate (clean itself). If you haven’t been driving at highway speeds for a while, the exhaust system may not have got hot enough to force this regeneration. At that point, the computer will inject extra fuel into the engine to make the exhaust run hotter. And, again, some of this excess fuel can find its way into the sump.

An oil change is your best plan of attack, and then keep a close eye on the level of the dipstick. Any increase in level should not be ignored.

I can only hope so. Trying to start an engine with an obvious and large fuel leak like the one you’ve described is really tempting fate. This leak needs to be fixed before attempting to start or drive the vehicle as it’s a major fire hazard.

Even turning on the ignition will have the pump spraying fuel everywhere from the leak, so I’d disconnect the battery until the hose is repaired and the leak stopped. There’s a chance the computer has detected the lack of fuel pressure, but whether that’s what is preventing the engine turning over is another thing. You may have multiple problems.

That’s not a huge mileage for an engine like this, and I wouldn’t expect to see timing chain stretch over that distance. However, it begs the question of how the vehicle has been serviced. Timing chains really should last the life of the car (or, at least, the engine) but if the engine hasn’t been treated to the correct oil changes and general maintenance, the timing chain can be one component that will suffer.

If the car was bought second-hand, it would be worth going through the service history to see if any scheduled servicing was skipped. This could be the root cause of the problem. It’s also important not to confuse a stretch timing chain with a worn chain tensioning system. The tensioner holds the chain tight, taking the slack out of it and allowing for some stretch to be taken up over the years of operation. If it fails or becomes weak, you might start to hear the chain rattling.

Based on probability, you either have a faulty oil filter which is not sealing properly, or there’s a crack or some other flaw in the boss (fitting) on the side of the engine that accepts the filter. Chances are the oil appears when the engine is cold and oil pressure is highest. The oil pressure (which all engines need to survive) is pushing the oil out through the weakest part of this assembly.

It’s not unknown for oil filters (especially cheaper brands) to have basic manufacturing flaws that allow them to leak, so that’s where I’d start my investigation.

When this car was new, the recommended change interval for the timing belt was nine years or 230,000km which is an awfully long interval by industry standards. In some markets, this figure was reduced to seven years and 180,000km, which is still a long interval, but much more sensible.

If it was my Land Rover, I’d be changing it even sooner, probably at 150,000km at the outside, just to be certain, as a snapped belt will turn the engine to junk in a split-second. While you’re at it, take the opportunity to change the water pump and idler pulleys while the front of the engine is apart. It’s better than having to go back and disassemble the same part of the engine a few months later when the water pump starts leaking.

A squeak when taking off from rest could be anything from a brake problem to a wheel bearing fault, a noisy engine drive-belt, bent axle, a dry suspension bush, worn universal joint or just about a hundred other things, including the driveshaft you already suspect.

Of potentially greater concern is the cut-off exhaust system or, more correctly, the previous owner. Anybody who cuts up an exhaust to make more noise is also a likely candidate to have driven the vehicle hard. It might be better to find a vehicle that hasn’t been messed with and potentially abused.

A sawn-off exhaust system shouldn’t harm the turbocharger or engine, but it can make a difference to performance due to reduced back-pressure. It also makes me wonder what else has been changed of fiddled with in the name of more power. Sometimes the performance will actually be improved, but you also open a can of legal and insurance worms by changing things like factory exhaust systems in what is a fairly agricultural way.

The sluggish performance and the erratic tachometer needle may not be related at all. That said, they could very well both be symptoms of the same problem. A lot of mechanics, when shown an erratic dashboard gauge, will start by checking for a bad earth point. A poor earth can lead to all sorts of problems, as a healthy flow of electricity is vital to the basic functions of any modern car.

But before you rush out to find an auto electrician, bear in mind that this sounds very much like a problem that would be covered by Mazda’s factory warranty. Provided you have had the car serviced correctly and it hasn’t been submerged in a flood or something equally drastic, the first step is to take it back to Mazda and allow the dealer to tackle the problem.

The Mitsubishi 4N15 engine in your Pajero Sport has a timing chain rather than a toothed rubber belt. As such, the chain should be good for the life of the vehicle rather than requiring periodic replacement as a timing belt does. However, this does not make the valve-train maintenance-free, as this engine requires valve clearance adjustments every 60,000km.

It depends on which engine your Navara has. If it’s a D22 with the 2.5-litre engine, the oil-change capacity is 5.6 litres. If your car has the three-litre engine, it will need 6.7 litres to complete an oil change. If your car is the later model D40 version, the 2.5-litre engine will require 6.9 litres. Those amounts should allow for an oil-filter change as well.

In each case, the recommended oil is a 5W40 semi-synthetic.