Mazda Problems

Mazda (and other car-makers) have been having lots of problems with the oil level rising in the engines of some of their diesel models. The problem is caused by the Diesel Particulate Filter attempting to regenerate itself. In an ideal world, these diesel vehicles would be driven for at least an bour or so at freeway speeds at least once a month. That would get the exhaust system hot enough for the DPF to regenerate on its own (burn the contaminants from the exhaust to ash and expel them, basically).

But in cars that don’t see this sort of use and are more commonly driven around the suburbs at moderate speeds, the exhaust never gets hot enough for this to occur. So, the solution has been to inject extra diesel into the engine to make the exhaust hotter and, therefore, get it all to a temperature where DPF regeneration can occur. The problem is that some of that diesel can get into the sump of the engine where it dilutes the engine oil. And that’s why you’re seeing the level rising on the dipstick over a period of weeks and months.

Diluted engine oil is bad news because it may not lubricate and protect the engine as well as non-polluted oil. The warning light you’re seeing is telling you that you might be at that point and that an engine oil change is probably a good idea, even if the service interval hasn’t been reached yet. Just draining some of the contents of the sump away is not the answer as the oil is already diluted by the diesel.

It’s a bit silly, isn’t it? There’s absolutely no reason for a speedo in an Australian delivered car to read to 260km/h, particularly in a car that would never manage to gain that much velocity without the help of a mine-shaft. There’s no ADR requirement for it, either, so it’s probably a hang-over from other markets where average freeway speeds are much higher than they are here. In Germany, for instance, where there are still unrestricted sections of autobahn, the 200-plus-km/h speedo makes more sense.

You’re probably right when you suggest this is all a one-size-fits-all approach by Mazda (and many other car-makers) who can save a few dollars by making only one speedo calibration and fitting it to cars for every market. More recently, a lot of cars have both a conventional and a digital speedometer fitted. Many owners have come to rely on the latter for clarity. My preference is for an analogue (needle) speedometer that has 100 or 110km/h at the 12-o’clock position on the dial.

This is a really common problem with this model (and the Ford Ranger with which it shared its mechanicals). Many buyers avoid this model for this very reason. Even though many fixes have been tried it seems that this car, shown a hill and a hot day, will often overheat.

Several theories exist including that the EGR valve is the problem, as it fails and allows coolant to escape (usually into the engine cylinders). But even when the EGR valve is working properly, this engine is prone to running too hot. Some other theories hold that the thermal management of the engine itself was just underdone and there’s no real fix for it. That’s borne out by the number of people who have tried different radiators, thermostats and cooling fans and still have a vehicle that overheats.

But you could try reverse flushing the radiator and making sure than every part of the cooling system is working efficiently and properly. That will maximise your chances of not having the engine overheat but, in this case, there are no promises.

Rubber window seals are a constant source of frustration for car restorers (and let's not forget the RX-7 Convertible is getting on for 40 years old now). The seals don't last forever (particularly in Australia with its UV radiation) and once the dealership supplies dry up, there's not always the demand for rubber manufacturers to continue to make them. Popular makes and models don't have quite the same problem, but even newer niche models like, say the latter-day Holden Monaro, is giving owners all sorts of problems sourcing replacement rubber parts.

Social media might be your friend here. Try to find an online RX-7 owners' group and ask the question, Even if there are none readily available, some car clubs have enough members that specialist manufacturers will run off a batch of replacement parts, provided the club buys a job lot. If not, you might just find another RX-7 owner who has stumbled on to a replacement rubber that was originally made for a different car (or application altogether) that will fit and do the job. Don't rule out finding a similar rubber seal and modifying it to fit your car by slicing off part of it.

That's quite high mileage, but in a modern car with vastly better metallurgy, engineering design and oil quality (particularly multi-grade oil) it's not impossible for a car with that sort of mileage to still be in perfectly serviceable condition.

Frankly, if you're not after something newer with newer tech and convenience, and you're still happy with the Mazda, the advice is probably to keep it and drive it till it will drive no further. As it is, if it's getting close to 300,000km, it's not worth very much to trade-in or sell second-hand, so keeping it and squeezing every last kilometre out of it is the budget-conscious way to go. The exception would be if a bunch of little things all go wrong at once. At which point, you're probably wise to quit it  - even though it's worth very little - as a means of not throwing good money after bad.

Rather than the steering completely locking up, it’s more likely you’re feeling steering that has lost is power-assistance. It can make the wheel extremely heavy and could feel as though the car won’t steer at all. This is linked to the engine stalling, because the power-steering on this vehicle is driven by a belt from the engine. No engine means no power-assistance.

The other questions, of course, are why is the engine stalling and why only on left-hand turns. There are plenty of things that can cause a modern engine to stall from a dirty fuel filter to a blocked injector or an electronic fault. And about a million things in between. An electronic scan of the vehicle might throw up a fault code that will help a mechanic unravel what’s going on.

It certainly looks like that could be the case. Mazda HQ has announced plans to stop production of the 6 at the plant that supplies Australian 6s, so barring a switch to a new supply-factory, that would seem to be so. There's a sense that some Mazda factories will continue to build the 6, but the suggestion is that this will only be for some limited Asian markets.

Unfortunately for those who like conventional vehicle packaging, the almighty SUV has just about killed off the traditional sedan and station-wagon.

We have heard some reports of Ranger and BT-50 (they're the same vehicle mechanically) suffering oil pump failures with fairly terminal results for the rest of the engine. The other quirk with this engine is that you can't drain the engine of oil and leave it for any more than a few minutes without the pump running dry and needing to be primed before the engine is started.

Not all mechanics know this and many a Ranger or BT-50 engine has been destroyed when the oil has been dropped from the sump and the mechanic has gone to make a cup of tea or do some paperwork. They return half an hour later, replace the sump plug, fill the engine with oil and start it up. But because the pump hasn't primed, there's effectively no oil pressure and the engine is reduced to scrap in a few short seconds.

The problem is partly to do with the different design of the pump and there are even companies that have engineered more conventional oil pumps to replace the standard units on these engines.

The starter motor on this vehicle is located down low on the front of the engine. Conventional wisdom is to remove the air-box and part of the intake trunking to access the starter motor's fasteners and wiring, and then remove the starter itself from below the engine bay after removing the plastic underbody protection panel. Don't forget to remove the negative battery terminal before starting any of this.

I can assure you the 2013 BT-50 was, indeed, engineered with a heater and this came standard with any BT-50. The dial that controls the coldness of the air-conditioning is the same one that controls the heating. Turn the dial all the way clockwise and you should have warm air entering the cabin through the various vents.

If not, then I'd suggest that a previous owner has blocked off the car's coolant supply to the heater core by rerouting the plumbing so the hot engine coolant no longer enters the heat exchanger in the cabin. This was probably done because the heat exchanger was leaking and this was a quick way to stop the leak and keep the vehicle operational, albeit without a heater. It's one of the oldest tricks in the used-car book.

The best bet is to take the car to a radiator specialist who will be able to figure out what has been removed or bypassed and reinstate the necessary hardware so that your car is heated once again.