Isuzu Problems

Air-conditioning relies on fans as well as the actual refrigeration system to move the chilled air around the cabin. If the fan isn’t working, that won’t happen. So a check of the fan in question would be a good place to start. Perhaps there’s a wiring fault, maybe the fan is intermittently failing to kick in.

There’s another possibility, too, and it’s more common than you might think. Some air-con systems tend to build up ice inside the system’s plumbing. If that happens, you’ll suddenly get no air-con and possibly even zero airflow through he vents as the ice blocks the trunking completely. The solution is to turn the system off at that point, allow everything to thaw and then turn it back on. Try that process next time the vents fail to see if that fixes it (temporarily).

Any time you have a grinding noise from the driveline of a car, it’s time to have it checked out. That’s because continuing to drive it in that condition might cause more damage than was already there. Grinding sounds from the area of the transmission can indicate worn bearings in the gearbox which, if caught early enough can sometimes be replaced without resorting to a complete transmission replacement. Even so, it will be a big job as the gearbox will need to be removed and pulled apart.

You may also find while you’re inside the transmission that there’s other wear that needs to be addressed, at which point the decision becomes whether to repair or replace. You can buy a reconditioned transmission from a specialist shop, or a second-hand one from what was once called a wrecking yard. If you do the latter, make sure the used gearbox has been tested and comes with some sort of warranty. The cost of a replacement could be anywhere from $1000 to $10,000 depending on what you buy and where you buy it from.

Rule of thumb says the correct on-road pressure is somewhere between 30 and 40psi for tyres like these. But since you’re losing traction regardless of inflation pressure, who knows. Clearly something else is going on here. Just for starters, the MU-X is fitted with both traction control and stability control which should rule out losing traction in the first place. Are these systems working? If not, you’re technically driving an unroadworthy vehicle.

How old are the tyres? Were they fitted to your previous vehicle and swapped over to the new one? Tyres have a finite lifespan beyond which the rubber compound starts to degrade and the tyres lose grip. That’s something to check. Perhaps the rubber has been contaminated by something like oil or grease. Has the vehicle ever been parked in a pool of oil or diesel? It sounds pretty daft, but is the fuel tank or filler neck allowing diesel to leak on to the tyres or flick up on to them as you drive?

You also need to be aware that as an off-road tyre, on-road grip will never be as good as a tyre designed to work mainly on bitumen. The tread pattern and compound are both compromises in the interests of going off-road, so you can’t expect passenger-car tyre grip from a tyre like this one on a vehicle like your Isuzu.

This make and model of tyre seems to be pretty well received among users, although some have mentioned a lack of wet bitumen grip as something to keep in mind. Don’t forget, either, that in really wet or greasy conditions, you can safely switch to high-range four-wheel-drive to prevent wheelspin and improve your safety margin.

There’s a bit to unpack here. The first is that the D-Max is rated to safely tow 3.5 tonnes, so it’s not as if you constantly have the vehicle overloaded in terms of what it’s towing.

But if you also have the tray full of gear as well as 2.3 tonnes of caravan on the hitch, you might find that you’ve been inadvertently running overloaded for most of the time. It happens more than you think. At which point, the Pedders specialist is right; you need a suspension upgrade.

Even then, however, you still need to stay within the manufacturer’s maximum GCM (Gross Combination Mass) and the GVM (Gross Vehicle Mass) to stay legal. You can sometimes officially upgrade the GVM with a suspension upgrade that’s been properly engineered, tested and approved (which Pedders is a specialist in) but the GCM is generally not able to be upgraded according to the law in each state and territory.

But none of this explains why a vehicle designed to two 3.5 tonnes is wearing out its rear springs with 2.3 tonnes hitched up. Is the tow-ball down-weight within the legal limit (usually 10 per cent of the weight of the towed load)? Incorrect loading in this manner could affect the springs. Perhaps a fully-loaded visit to an accredited weighbridge might net more answers.

However, if it’s a simple case of the springs wearing out prematurely, then it’s possibly Isuzu’s problem to fix under warranty. Perhaps there was a bad batch of springs fitted at the factory that is affecting your vehicle and others built at the same time. Stranger things have happened.

Australian dust is pretty amazing stuff. In some locations, it’s so fine, it can get past even the best rubber seals and into a car’s cabin. Problem is, once it's found its way into the heating and cooling plumbing on your car, every time you turn on the climate control or open the vents, you’re going to smell dust.

Cabin filters can help reduce this, but once the dust has entered the car, there’s very little chance of ever removing it completely.

However, if the smell is only present when you’re travelling on a gravel road, it might be that there’s a more obvious leak that is allowing the dust inside at that point in time. Check all the door and window rubbers, not forgetting the tailgate as the rear of the car is where the dust often enters.

If there are no rubber seals showing damage (or a tell-tale trail of dust) make sure each panel is properly aligned and that the weight of a spare-wheel rack (if you have one fitted) hasn’t distorted the tailgate hinges.

The other thing to do is to put the climate-control on recirculate and switch on the air-conditioning as this will pressurise the cabin and help keep the dust from being sucked into the car. It’s amazing how effective this can be.

Any time a diesel engine produces black smoke, it’s doing so because too much fuel is entering the engine. The danger then is that the engine will start to run hot and that can cause all sorts of meltdowns. But combined with a knocking noise, black smoke can also signal serious internal engine damage.

The best advice is to not drive it any farther and get a diesel specialist to look at it. Diesel engines often make a knocking noise as a normal part of their operation, but if this noise has changed, then something’s wrong.

What you’re experiencing is the front and rear axles fighting each other. Us old-timers call it axle wind-up and, as the name suggests, it’s what happens when the various wheels need to turn at different speeds, but can’t.

When you’re in 4H, you’re effectively driving the front and rear axles at precisely the same speed. Logic says this shouldn’t matter, but, depending on what lumps and bumps they’re covering at the time, there are times when the front and rear wheels need to travel at slightly different speeds. Throw in full steering lock, and you’ve just made things very difficult for the driveline with all sorts of competing forces being fed around the various tyres, axles and driveshafts.

This is far from limited to the Isuzu, and many four-wheel-drives without a centre differential (such as your D-Max) when driven at full lock in 4H will exhibit the same shunting and apparent loss of power. The power loss, meanwhile, is simply those front and rear tyres fighting each other; nothing to do with the engine at all.

When you shift back to two-wheel-drive (2H) the front and rear axles are suddenly free to turn at different speeds, and the sensation goes away. This whole situation is why you can’t use 4H on dry bitumen in a four-wheel-drive vehicle without a centre differential. Meantime, there’s no fix for it other than learning when and when not to engage 4H.

It sounds very much like the vehicle has gone into limp-home mode. This is a self-preservation system whereby the engine and drastically reduces the power it’s producing, limits top speed and often locks the transmission into a low gear. Something has happened that has caused this, and a common reason is that something in the engine, fuel system, or (more likely) the transmission has started to get too hot with the strain of towing.

With luck, full operation will be restored once the vehicle has been allowed to cool down. But you may need to visit a dealership to have things reset. It’s always a good idea to do a full engine and transmission fluid and filter change after any overheating event anyway.

Okay, here’s the bottom line: All engines use a little bit of oil. If they don’t there’s either something wrong with the oil pump, or the owner is kidding themselves and not checking the oil level correctly. Modern turbo-diesels also 'breathe' a little oil back through the engine as part of the emissions control system, and owners with an aftermarket catch-can system often find a bit of oil winds up in there instead of being burnt in the engine.

The question is how much is too much. I don’t think 700ml per 2000km is excessive and your dealer’s views will be based on the official figure from Isuzu. But in the real world, owners are reporting oil consumption of around a litre to 1.5 litres per 5000km. At which point, your engine is right on the money.

How you drive the vehicle and whether you tow a heavy load will also affect oil consumption, as will ambient temperature and the type of oil you use. It’s a fact that modern, lower-friction engines are designed to use a little oil in the name of saving fuel, and it’s something car owners need to get their head around. Keep an eye on that dipstick and you should be fine. Checking the oil on a regular basis will also tell you whether the engine’s drinking habits have changed; a much more valuable piece of knowledge to have.

This is probably a simple case of an automatic transmission doing what it’s designed to do. In order to keep the engine in its comfort zone (and making sufficient power and torque to haul the caravan at the speed you’ve chosen) the transmission will shift through its gears to achieve that happy balance.

Any time you encounter a hill or even a headwind (and it’s more so with a heavier caravan) the transmission will assess what speed you want to hold, and then (via changing gears) keep the engine at a speed that supplies the necessary performance. Even a hot day can cause a change in the shift patterns as the transmission aims to take the strain off the cooling system by giving the engine and easier time. Again, a big, heavy caravan will amplify this effect.

However, if the transmission is changing gears for no apparent reason, then you may need to have the calibration checked and perhaps even reprogrammed. Don’t forget, though, that a modern transmission is a pretty clever piece of gear that can even choose to shift down gears going downhill to take the strain of the vehicle’s brakes. Don’t confuse an active transmission with a dud one. And if you still think the behaviour is odd, then an electronic scan of the vehicle might provide more information.