Mazda BT-50 Problems

It's quite probable that the check-engine light was triggered by the worn out condition of the battery you replaced, not the brand new one being fitted. Such cars hate low voltages, and that's precisely what a worn battery produces. That said, changing the battery can sometimes cause a modern, computerised car to throw a fault code, and when that happens, the check-engine light will illuminate.

You can try to re-set the vehicle's computer by disconnecting the battery and leaving it for an hour. Then reconnect the battery and see if the light has disappeared. If it hasn't, it may be that the computer simply needs to relearn a few parameters after having been disconnected from the power when the original battery change was made. A decent drive might return things to normal.

But don't forget the basics: Check the condition and cleanliness of the battery leads, terminals and make sure that all the connections are tight. If there's still no joy, have the vehicle electronically scanned and let the computer tell you precisely what's wrong.

The rule of thumb states that if the engine fires on starting fluid sprayed down the intake, but won’t run on the fuel in its tank, the first thing to check is the fuel pump. Just because there was some fuel present when you cracked the seal on the fuel injector, does not necessarily mean that there’s enough of it or the fuel pressure is sufficient to start the engine.

Modern common-rail diesel engines use very sophisticated fuel systems which use super-high pressure. Without a pump to build up to this pressure, the injector won’t deliver the right amount of fuel for successful running. But you should also check the operation of the glow-plugs as well as the condition of the fuel filters. An electronic scan is also a good idea at this point, before you start replacing expensive bits and pieces.

Be extra careful fiddling with engines like this one, especially if you’re messing about with the injectors and fuel system. The inherent pressures are so high, that a leak can act like a water-jet cutter; sufficiently powerful to remove a finger.

After 100,000 hard off-road kilometres, you'd be wise to check pretty much every system and component of your car, including the wheel bearings. Bush tracks and rough regional roads put all sorts of stresses and strains on mechanical bits like bearings, suspension, brakes, bushes and the whole driveline.

If you read most owner's manuals closely, you'll see that the recommended servicing schedule is based on normal or moderate use, not hard-core off-road work like you've been doing. With that in mind, the advice is to shrink the service intervals and the distances at which major parts like wheel bearing are checked and/or replaced. Give some thought to changing out the vehicle's fluids, too, including the front and rear differentials, as contamination from water crossings can destroy the lubricant and lead to extensive internal wear.

Anything is possible if you have enough money to throw at the project, but at some point, each project begins to cost more than it will ever be worth.

The real mystery, though, is how you came by a petrol-powered BT-50. In Australia, the BT-50 was sold only with a range of diesel powerplants. Petrol-powered BT-50s were made and sold in regions such as the Americas, South Africa and parts of Asia, but not here. Either that or you have a Mazda fitted with a Ford Ranger engine, as Ford did offer 2.5-litre petrol engine on Rangers from 2011 to 2015, but only on base-model, two-wheel-drive versions. That option was then discontinued.

So maybe you have a privately imported Mazda, at which point, it’s very hard to know what diesel engines will and won’t fit. The bottom line is that if you want a Mazda BT-50 with a diesel engine, the simplest thing to do is simply buy one. Chances are you’ll spend less overall than converting an existing car from petrol to diesel. Swapping a petrol engine for a diesel could involve everything from a different fuel system, wiring, transmission, differential ratios and even things like the radiator and front springs. It’s a big job.

If we’re talking about the current model D-Max and BT-50, then yes, the entire driveline should be interchangeable. Under the skin, both the Mazda and Isuzu utes are the same vehicle. Car makers enter into joint ventures like the development of this pair of vehicles to keep costs down by sharing the expense of developing, engineering and testing parts like engines, transmissions and, of course, drive-shafts and CV joints.

While most joint ventures like this one will arrive at two vehicles with some visual differences and usually some details differences inside, when it comes to the oily bits, making specific driveline or suspension parts for one vehicle over the other is defeating the purpose of the joint venture in the first place.

The first thing to do is take a look at where the car was parked. You’re checking for a pool of transmission fluid that has leaked out over time while the car has been stationary. A low of fluid can cause all sort of problems in an automatic transmission, including the one you’re experiencing.

However, the transmission in this vehicle is well known for noises when selecting gears from Park, particularly after it has been sitting for a while. The problems were usually traced to the valve body of the transmission and some valve-body assemblies were replaced as part of a technical program conducted by the manufacturer.

The catch, though, is that the service bulletin involved suggested that only transmissions in cars built up to 2014 were affected, and since your car is a 2018 model, it shouldn’t have the same problems. But it wouldn’t be the first time a problem thought solved by a car-maker has resurfaced in subsequent models.

Probably the most common cause of difficult hot-starting in a diesel engine is wear in the fuel pump. If the pump can’t generate the correct pressure due to wear, which is exacerbated by heat, then it may not generate the pressures required to operate the fuel injectors.

This particular engine has a fuel pump which has been known to wear and allow the fuel inside it to overheat, causing the vehicle to go into limp-home mode. But the engine (and many others like it from other brands which use common-rail injection technology) are also notorious for wearing out their fuel injectors over relatively low kilometres. Worn injectors could also be a cause of difficult hot starting.

It sounds awfully like the car has entered what’s called limp-home mode. As the name suggests, this allows the ute to run just enough to get you to a workshop without damaging anything else. Limp-home is usually associated with a problem in one of the car’s systems, whether that’s electronic, fuel-system, exhaust system (DPF) or a mechanical fault with the engine or transmission. It’s kind of a self-preservation function.

The good news is that you’re still well and truly overed by the factory warranty, so it’s back to the dealership for your BT-50. This is absolutely Mazda’s problem, not yours.

Unless you’ve changed the way you drive, a sudden jump in fuel economy suggests something wrong with either the mechanical or electronic side of things. Have the vehicle scanned and see if it throws any fault codes. From there, you can work out what component is giving you grief and target the problem accurately, rather than mess around for weeks flying blind.

One reason for the sharp increase in fuel consumption could be that the vehicle’s diesel particulate filter (DPF) is full and needs to be regenerated. If you’re not doing long, highway miles, the computer can take matters into its own hands and dump extra fuel into the exhaust system in an attempt to get the exhaust hot enough to regenerate the filter. But you could also be dealing with a faulty fuel-pressure regulator, worn injectors or even something as simple as a blocked air filter.

This is one of the problems with the way the prices of band-new vehicles are haggled over. Had there been just a simple checkout price (as there is with nearly everything else we buy) this confusion probably wouldn’t have crept in. I take that, having asked for the tray upgrade, you then paid attention only to the final price being offered by the dealer.

Regardless of whether the dealer is trying to stall you with talk of a two month wait is a side issue. And perhaps you can hold out and force the dealer to supply the vehicle as per your contract of sale. Then again, if the mistake was a genuine one by a member of the sales staff (who could conceivably lose their job over such a blunder) then what’s the moral solution? Perhaps there’s a compromise to be made by both parties. I can understand you not wanting to pay an extra $7000 for a different type of tray, but surely that’s not the best result for anybody. In an ideal world, perhaps one solution would be for the dealer to provide the tray at their cost price (so they don’t lose money on the deal) and you get a cheap(er) tray because you’re not paying retail. Yes, it’s complicated. But that’s what happens when commerce meets karma.