Nissan Problems

Let’s start with the black exhaust pipe. All cars that run on unleaded petrol have a sooty black exhaust. The soot will be thicker if the car isn’t tuned properly, but really, the blackness is just a by-product of burning ULP.

Your oil use of about a litre every 1500km is getting towards the top of what is acceptable. Even then, it’s more than this engine should consume. The fact is that all engines use some oil, but it’s usually not enough to require topping up between oil changes. But with your usage rate, you’d need to keep a close eye on the dipstick.

The oil is clearly going somewhere, so check on the ground under where the car is parked each night and look for a pool of oil that suggests the problem is an external leak rather than internal engine wear. From there, have a workshop conduct a compression and leak-down test. The results of this will tell you if the engine’s internal parts are worn and leading to the oil being consumed.

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.

The ZD30 will probably not be remembered as one of Nissan’s greatest engines. In good condition and running properly, they’re not a bad unit, but they have managed to develop a reputation for – as you’ve identified – giving problems long before they should.

Any off-roader’s engine is liable to overheat, especially when you’re working it hard in the bush with minimal air-flow through the radiator. Many Patrol owners have identified this and fitted larger, aftermarket radiators to fix the issue. A bigger worry is the engine’s propensity to explode – usually – number three of four piston with catastrophic results.

The trade has a few theories including a build-up of oil and soot (which forms black gunk) that partially blocks the inlet tract that causes uneven mixtures across all four cylinders. At that point, you could have hot-spots occurring that can potentially melt pistons. Another theory holds that the same black gunk was messing with the engine’s sensors and allowing them to send false information back to the computer, again leading to incorrect air-fuel mixtures.

Boost spikes were another problem, apparently caused by the engine’s slow response to commands from the computer. In extreme cases, turbo-boost could increase violently and damage pistons. Even then, it wasn’t that simple, because Nissan itself seems to have misunderstood the engine, originally specifying an oil capacity of too little, leading to oil starvation and engine damage. The company quickly added a couple of litres to the specification (for a total of 8.3 litres) and instructed its dealers to shorten and recalibrate dipsticks when the cars came in for servicing.

For all that, the ZD30 has gathered its admirers who value its performance and reduced fuel consumption over some other turbo-diesel Patrol engines. For our money though, if you can afford it, the bigger, less stressed TD42 turbo-diesel is the pick of the Patrol engines from this era. The catch there is that the TD42 was only available with a five-speed manual while the ZD30 could be had with an optional four-speed automatic.

The very fact that you’re looking at two vehicles that fit into your budget but have travelled such vastly different distances should tell you all you need to know about the Nissan. Frankly, the Navara D22 and D40 don’t age well. In fact, many owners have found out the hard way that a Navara just can’t match the Toyota HiLux of this vintage for longevity and the ability to cop punishment over time.

I’m certainly not saying that the HiLux was perfect, but compared with the Navara’s litany of faults and problems that covered everything from rattling timing chains to coolant leaks and odd design elements such as the bottom of the radiator being lower than the lowest part of the chassis cross-member (not good for off-road work) the Toyota was much better. Granted the Navara you’re considering has very low mileage, so it should be okay for a while…just about till you hand it over to your son to break.

It sounds as though the vibration you’re experiencing is coming from the driveline. Perhaps it’s the engine but more likely it’s something in the transmission since the problem is worse when the car changes gear. That the problem occurs when climbing a grade suggests that it’s related to the engine being under load at which point the whole driveline – gearbox and driveshafts – are also loaded up.

It could be something within the transmission itself, a bent driveshaft or even something relatively simple like a worn CV joint. Carefully, and when it’s safe to do so, find a big, open area like a deserted car-park, turn the steering wheel all the way to the left and drive slowly in a tight circle. Now do the same on full right-hand lock. Can you hear any clinking or clunking noises? If you can, you have worn CV joints. If not, you need to dig deeper into the cause and that will require getting the car on a hoist and inspecting the driveline.

This model Navara was known for a couple of faults that could cause it to enter limp-home mode (which sounds like what’s happened given the engine is no longer making full power). The first was a batch of dud exhaust-gas temperature sensors which had a habit of dying young. If that happened, the engine would go into limp-home mode to avoid overheating (and damaging) the turbocharger, even though there was no actual problem beyond the sensor itself.

The other problem with the 2.5-litre turbo-diesel was that the primary timing chain was a single-row item that was, frankly, underdone and could stretch before the vehicle had covered even 80,000km. If that happened, the camshaft-position sensor would become confused and could trigger a limp-home condition. There’s a replacement timing chain that is actually double-row (stronger) that many owners fit as a solution.

There’s absolutely no correlation between body styles (hatchback versus sedan) and the propensity for leaking brake cylinders. The difference between your mum’s and your previous car and the Tiida is probably all down to the quality of the parts, not whether it’s a hatch or sedan.

Brake cylinders leak when the rubber seals inside them fail. But because the cylinder is hidden within the brake drum, a leak is often only found when the car is being serviced or inspected for a roadworthy certificate. And as you’ve found, that’s often too late to prevent the brake shoes becoming contaminated by the leaking brake fluid.

The best way to avoid leaking brake cylinders is to have the braking system flushed regularly. It’s also important to replace any leaking wheel cylinder with a good quality unit. I’m tipping the reason your cylinders failed the second time was because the original ones were replaced with cheapies (possibly sourced online) which simply weren’t as good as the Nissan originals. Always beware when buying replacement parts of any sort that they’re good quality, particularly when it comes to critical safety systems like brakes.

The simple answer, Andrew, is that the 2.5-litre turbo-diesel engine in your Navara has a timing chain rather than a timing belt. However, it’s not that simple, as the engine uses two chains, rather than a longer, single timing chain.

The primary timing chain on your engine is a single-row chain while the secondary chain is a duplex (or double-row) chain. The secondary chain doesn’t seem to give too many problems, but many owners have found that the lower, single-row chain seems a bit underdone and has been known to stretch in service. When that happens (if the stretching is enough) the pistons and valves inside the engine can collide with fairly devastating results. The chain guides can also show signs of premature wear in these engines.

The trade recommends that the primary timing chain in these engines is changed every 80,000km or so and inspected for wear and stretching every 40,000km. Which pretty neatly sidesteps all the advantages of a timing chain over a timing belt.