Ask The Guide

The usual procedure for flushing a cooling system is to drop the existing coolant (usually by disconnecting the bottom radiator hose) fill the system with distilled water and whatever flushing chemical the workshop uses, restart the engine, drive it around for a short time until everything is at operating temperature, dump the water and flush mixture and refill the cooling system with the proper coolant.

You can also simply flush the radiator (and not the rest of the cooling system) by disconnecting the radiator hoses and running a hose through the radiator, usually in the opposite direction the coolant flows. But this is a much more simplistic flush and doesn’t change the condition of the engine crankcase’s cooling passages.

It’s possible that the flushing process has loosened some rust or scale that then blocked the cooling system somewhere else (the thermostat is a prime suspect) and if that’s the case, the process needs to be repeated until the water coming out of the cooling system is nice and clean and not tainted with rust or scale or anything else.

Revving the engine to get the flushing mixture to do its job is not really a problem, but could also be achieved by actually driving the vehicle (which would also get it up to temperature faster). But, really, provided the temperature gauge hasn’t been allowed to move into the red zone, you shouldn’t have damaged anything. But you do need to know why the operating temperature of the engine is now higher after a cooling system flush.

It sounds like there’s either a problem with the throttle pedal, the throttle mechanism itself or, most likely, a glitch in the communication between the two. Instead of a throttle cable directly linking the pedal to the throttle, modern cars use what’s called fly-by-wire. In this case, that means a throttle pedal where input is converted to an electrical signal, which is then transferred by the computer to the throttle telling it to open. If there’s any wiring or software problem within this system, you could easily experience this sort of problem.

You’re quite right, too, that this represents a very dangerous situation. Many crashes have been caused by a following driver assuming the car in front was about to take off. And when, for whatever reason, it doesn’t…

If the computer won’t tell you what’s happening, an auto electrician should be able to take readings from the throttle pedal and the motor that actuates the throttle itself. From there, they should be able to discern which component is not playing the game properly.

It sounds like the head unit and its Bluetooth functions have suffered a pretty major electronic failure. The good news is that you can replace the head unit for reasonable money these days, and get a better unit with more features into the bargain.

But before you rush out and replace the unit, try to find the reset button (often a small hole into which you poke a probe) to effect what is basically an Ctrl-Alt-Del reset. This will sometimes restore the unit to full functionality, so it’s definitely worth a try. You could also try disconnecting the car’s battery overnight to see if that resets things.

This engine uses what’s called a wet timing belt. So, instead of the toothed, rubber belt running under a cover as most timing-belt engines do, the Ford engine runs its timing belt inside an oil-bath. The idea is that the oil will lubricate the belt, but experience has shown that sometimes, the oil can degrade the belt, causing either belt failure or contamination of the rest of the engine’s oiling system. Many mechanics regard the wet timing belt as a liability rather than an asset.

Some owners have had no bad experiences, others haven’t been so lucky. However, it’s probably worth noting that the replacement for this engine (announced recently) has reverted to a conventional timing chain in the interests of durability and reliability.

This is not an uncommon thing with some Hyundai models of this vintage. Because of either poor design or materials, some Hyundai engines wear faster than they should. The first signs are rough running, noisy operation and oil consumption. On that basis, I reckon you may have one of those affected engines. That’s supported by the borescope examination that showed wear and the fact that the engine needed two litres of oil to bring it back to a normal level.

It's a fair bet the 1000km monitoring will show the engine has a thirst for oil, at which point it probably needs to be either replaced or rebuilt. My experience suggests that Hyundai is taking this seriously and is replacing engines under warranty with an improved unit that should last much better.

Give the dealership every chance to figure out what’s actually happening under the bonnet and then the time to make it right. You now have what’s called a pre-existing issue, so even if the warranty runs out, Hyundai knows the problem occurred while still within the warranty period. If your case is denied, then it’s time to contact Hyundai Australia’s customer service department and then, if you still don’t have any luck the ACCC which administers Australian Consumer Law and will be well versed with this issue.

The first thing to do is drive the car yourself and see if there’s a pattern to what’s happening. Until then, you have even less idea of what’s going on and a diagnosis is all but impossible at that point. You might find that the car is cutting out after a period of driving (maybe caused by a dirty fuel filter) or when the engine reaches a certain temperature (possibly a sick crank angle sensor).

I’d also recommend an electronic scan to see if any fault codes show up. These codes can be very specific and will often lead you straight to the root of the problem.

The fact that the scan doesn’t throw up a fault code could be an indication that it’s something pretty fundamental at fault here. Have you checked the car’s earth points and the tightness and cleanliness of the battery terminals? Apparently simple things like this can easily cause a random misfire. How is the condition of the battery and the charging rate? Modern engines hate low operating voltages.

But don’t rule out a problem with the fuel system, either. You might have a faulty fuel pump or a dirty fuel filter or even a dud injector that’s causing the glitch. Don’t forget to check the wiring to these components, either as a simple loose wire could be the problem.

If you do need to dig deeper, you could try checking the engine’s compression and the clearances of the engine valves. Even something like a cracked cylinder head or faulty head gasket can cause a misfire that shows up at, say, a particular engine temperature, but not at other times.

A clunk during gear changes often indicates wear in the transmission’s internals or even the torque converter. But you might also find it’s not the gearbox at all, but something elsewhere in the drivetrain such as a universal joint on the driveshaft or even the differential.

A transmission specialists is likely to have either seen this exact problem before, or will be able to quickly diagnose where the noise is coming from. That’s the first step, as you’re otherwise flying blind. Clunks and noises can move along the length of the driveline, making them very hard to track down precisely.

In the old days, the advice on this would have probably have been to have the fuel injectors cleaned. But these days, the modern diesel is a much more complex and sophisticated thing, and black smoke from the tailpipe could be any number of things to do with the fuel system.

You may find the injectors are, indeed, the problem, but you need to check the condition of the pump, filters, EGR valve and even the turbocharger and its plumbing. Something as simple as a split in the plastic turbocharger piping can lead to excess black smoke.

This is not as simple as perhaps it should be. Different carmakers use different methods to calculate cargo space, and Mazda uses the VDA method which uses 200mm X 100mm X 50mm blocks to determine the volume. In this case, the CX-5 has a volume of 438 litres with the rear seats up and 1340 litres with the seat folded down.

However, you need to know the dimensions in centimetres, so here’s how it pans out: The CX-5 has a luggage space length of 89.7cm with the rear seat in place, 171.5cm with the seat folded, a luggage space height of 82.7cm and a width of 105cm at its narrowest point.

Perhaps that helps, but the best way by far (if possible) is to visit a Mazda showroom with the wheelchair in question and physically see if it fits.