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Emissions compliance spoiled diesel simplicity and reliability.


Years ago we’d have laughed if someone said 4WD diesel engines are higher-maintenance and more likely to break down than petrols, but that’s the situation today. The latest diesels are high-maintenance and fragile.


Traditionally, a diesel wagon or ute is the preferred bush-travel machine, offering performance with economy and reliability and, until relatively recently, mechanical simplicity.

However, modern diesels must meet tight emissions laws and that requirement has increased complexity and drastically reduced reliability.

To meet emissions regulations all current diesels must have variable-geometry or twin turbocharging and intercooling, very high pressure injection – 1600 bar plus – to atomise fuel droplets to almost molecular level, exhaust gas recirculation (EGR) and several types of exhaust after-treatment devices.

Today’s diesels typically are fitted with expensive and fuel-quality-sensitive common-rail fuel injection, closed-circuit crankcase ventilation, EGR, diesel particulate filters (DPFs) and, in some cases, catalytic converters that requite diesel exhaust fluid (AdBlue) injection.

Yesterday’s diesels were much simpler than their petrol-fuelled contemporaries, but the situation is now reversed. It’s much easier to diagnose and repair problems in a petrol 4WD than a diesel one. Also, our bush testing has shown that today’s petrol engines have fewer mechanical and electronic issues than modern diesels.

At OTA we owned a complex diesel wagon (Land Rover Discovery 3) but we sold it because it was unreliable and expensive to maintain. (Yes, we did make the new buyer aware of the issues.)

Initially, we put those reliability issues down to the traditional ‘British Disease’ that earned UK auto companies global scorn for many years, but our testing and the experience of many owners with other modern diesel vehicles show that there are massive reliability problems across the board.

Our current bush mount is an old 75 Series LandCruiser tray-back, with a simple 1HZ diesel under-bonnet. Would we contemplate replacing it with a modern diesel ute? No chance. If Harry HJ gets replaced by a modern machine it will be a petrol hybrid ute, when they become available here – some 20 years behind USA initiatives.

This sounds like heresy, we know, but the current diesel reliability situation is drastic.


Diesel failures


Let’s follow diesel fuel flow from the tank to the tailpipe and see where things go horribly wrong.

In theory, the standard fuel filter will block water and contaminants, allowing only clean fuel to pass through to the common-rail injection pump. That was fine back in the days of fuel filters that could pass particles up to 10 microns, but most common-rail systems require two-micron filtration. That’s the size of a bacterium!

Micron ratings can be confusing and it’s important to know if a filter has a ‘nominal’ rating or an ‘absolute’ rating, and what its Beta ratio efficiency is… but that’s a separate topic.

Diesel fuel that meets the Australian Standard – let alone fuel that has been carelessly stored in unhygienic tanks – can still contain chemicals that ‘coat’ a very fine filter, increasing pressure on the inlet side and forcing larger particles through. Emulsified water may also pass though.

Vibration from rough-road travel can also stimulate filter ‘breakthrough’.

This didn’t matter in the ‘good old days’ when injection pumps had wider tolerances, but high-pressure, common-rail pumps have extremely fine tolerances and contamination will cause buildup, wear or total failure.

It’s the same with modern injectors that have to deliver tiny computer-controlled fuel parcels, up to five times per injection cycle. Some of them have check valves with steel balls only one millimetre in
diameter. Can you imagine how little contamination it would take to unseat that little ball?

Literally thousands of Australian 4WD owners have suffered fuel system damage, caused by contaminated fuel. That damage typically costs upwards of $5000, using factory components. After-market common-rail pumps are around the $1000-$2000 mark and injectors range from around $350-$600 each.

That’s the bill if you’re lucky! If you’re unlucky the contaminated pump and injectors over-fuel the engine, cracking pistons and causing total failure. Then it’s a 20-grand bill.

Filtration is the key issue here and existing standard filters just aren’t up to the task. Take a look at a modern heavy truck diesel to see what filtration on 4WD diesels should look like.

However, if you fit additional filtration to your new 4WD engine you lose your engine warranty.

Even when fed on quality fuel, modern common-rail injectors aren’t as durable as the old-fashioned, low-pressure ‘squirters’ of yesteryear. Where yesterday’s cruder, single-squirt injectors were usually good for 200,000km or more the modern unit that injects multiple times in every combustion event does much more work and has to tolerate much higher pressures.

Common-rail injectors need to be considered regular service items and should probably be replaced no later than 100,000-120,000km.

High pressures also take a toll on injector sealing washers and lines and they shouldn’t be re-used after injector replacement.

On some common-rail engines you can’t change the fuel filter without the aid of a computer and connector to prime the filter without the risk of running the fuel injection pump dry.

And all that is just fuel system bad news! There’s more drama in the combustion zone.

Modern diesel makers couldn’t resist chasing the power and torque gains that turbocharging, intercooling and atomised injection conferred. Nearly all common-rail engines have more than twice the torque of their same-sized turbocharged predecessors and around three times that of non-turbo diesels that were twice the size.

However, the combustion zone components haven’t changed all that much, so it’s now ‘normal’ for engines to have more ‘blow-by’ of combustion gases into their sumps. These gases combine with sump oil to form sludge that blocks oil pickups and passages.

The higher combustion zone pressures can also force gases past injector sealing washers, further contaminating engine oil and creating oil leaks.

Contaminated oil and carbon compounds
are sucked into the inlet manifold through the positive crankcase valve (PCV) and to ensure there’s sufficient suction, the PCV connection is upstream of the turbo. That means the turbo, intercooler and inlet manifold are coated with oil and carbon compounds.

Sludge in a sump can aggregate over time around the oil pump pickup screen, even in engines that have regular oil changes. Without warning that pickup restriction can reach a tipping point and engine seizure occurs.

Contaminated, sludgy oil has caused many diesel engine seizures across all brands and the cost, typically, is around 20 grand, plus any recovery costs.

Engine makers also followed the fashion to extended engine oil drains, so we now have half-sized, highly stressed engines, with small, sometimes contaminated oil volumes and extended oil drain periods. What are they thinking?

Many people drain engine oil between major services, but on some modern vehicles, fitted with variable-pressure oil pumps, you need to do the job very quickly, or risk oil pump damage, caused by oil starvation in the pump. Who on earth designed that?

But, as the man once said: “There’s more!”

The emissions control kit fitted to modern diesels brings many problems of its own.

Many 4WD owners are tempted to blank off EGR valves and fit catch cans to trap crankcase oil mist before it can coke up turbos and inlet manifolds, but we’ve covered the illegality and perils of that route in our story: Leave your common rail diesel engine alone’.

Diesel particulate filters are fitted to most modern diesels and they’re intended to trap particulates and soot in a fine ceramic mesh. That collection is burnt off – theoretically – at regular intervals by highway driving, or by ‘regeneration’.

The regeneration process is usually done automatically, by a late injection of fuel, after primary combustion, or by a fifth or seventh injector in some engines. The heat of late injection hopefully burns the build-up out of the filter. However, not all the injected fuel is burnt and some finds its way past the piston rings and into the sump.

Some oil dipsticks now have an upper limit mark, in addition to the ‘low’ and ‘normal’ oil level marks. This upper mark indicates too much fuel dilution of engine oil and shows that an oil drain is needed urgently.

The light truck engines fitted to working 4WD and motorhome vehicles – Isuzu, Fuso, Hino, Iveco and Mercedes-Benz – are better engineered than the light commercial engines fitted to 4WD utes and wagons and they don’t seem to have the DPF issues that plague small diesels.



DPF fire hazards


In late 2017 Ford and Mazda announced recalls of more than 70,000 Rangers and BT-50 utes that were factory-fitted with DPFs. The reason for the recall is the high risk of fire in these vehicles – there have been more than 30 to date – caused by grass buildup around the DPFs. There was no immediate ‘fix’ for this, we discovered, because one of the OTA Team vehicles is a Ford Ranger and its owner took it to his local dealer in response to the recall notice. The temporary ‘fix’ was instruction by the dealer not to park in long grass!

Ford came up with a ‘protective’ plate, but on a trip from Balgo down to Kiwirrkurra, one of the convoy vehicles was a Ford-modified Ranger. It needed daily clearing, because the plate did nothing to prevent grass seed buildup.

(A ‘fix’ we’d suggest is checking under your bonnet every few kilometres if you’re travelling in grassy areas. A piece of steel wire – around eight-gauge – with a hook bent in the end of it is a useful means of raking grass out from around the DPF.)

We’ve also heard of several fires in 79 Series LandCruisers, caused by grass combustion from DPF heat.

Little wonder there’s a steady after-market trade in emissions-equipment cheating and removal. But there’s a catch.

In the USA and Europe there’s regular, random emissions testing at designated facilities and it’s only a matter of time before we have that scourge here. Already some State transport authorities are spot-checking vehicles for signs of emissions-kit tampering.

Vehicles that don’t comply earn their owners heavy fines and defect notices.

But, there’s still more…



To comply with the current round of emissions laws many 4WD makers have fitted diesel exhaust fluid (AdBlue) SCR systems to scrub NOx out of exhaust gases. These are common in Europe and the USA and are already on many Australian-market 4WDs.

We’ve explained the chemistry of this system and it works reasonably well, but it’s yet another item to worry about and it’s expensive at replacement time.

Also, if the tank leaks or you use up your AdBlue in the middle of the Simpson Desert your engine will go into limp mode and then shut down. Great, eh?



Emissions laws are the root cause


The World Health Organisation estimates that one in eight worldwide deaths (seven million premature deaths a year) is due to air pollution, with transport being a major contributory factor.

Global emissions laws came into force in the 1980s, but only started to affect reliability in the late 1990s. Since then, lawmakers around the world have demanded tighter and tighter emissions levels and engine designers had to comply.

We all want fewer carbon and other tailpipe emissions, but no-one except spare parts sellers wants that to come at the cost of reliability.

Also, the law of diminishing returns ensures that the benefits from the latest emissions targets are relatively minor, in comparison with their cost and complexity.

The fact that the current diesel emissions regulations cannot be met in any real-world scenario has been demonstrated by on-road testing in Europe and the USA. VW was caught red-handed, cheating US EPA laws, but every vehicle brand recently roadside tested in the EU violated nitrogen oxides (NOx) emissions laws – some of them by a huge margin.

In road tests on almost 100 vehicles,
ordered by a French commission on diesel emissions, Renault and Nissan vehicles produced more than eight times the regulatory NOx limit on average, with most of their Euro 6 models closer to 10 times the limit.

Renault told the commission that the NOx-cutting exhaust gas recirculation (EGR) in its diesel engines had been found to cause serious turbo clogging problems. To overcome this condition engineers had programmed the EGR to shut down outside a narrow range of air intake temperatures: 17-35 degrees Celsius.

Mercedes-Benz defended a class-action lawsuit in the United States following revelations that the emissions treatment system in some of its Bluetec (AdBlue) turbo-diesels shut down when temperatures dropped below 10 degrees Celsius, allowing NOx emissions far above EU and US EPA limits. The company had to recall and modify 774,000 diesel vehicles in Europe to avoid massive fines.

Fiat Chrysler was also under investigation by the EPA and CARB, and Ford, GM and Cummins also had to defend major lawsuits.

The frustration for motorists is that they’re paying through the nose for emissions control hardware that doesn’t work, yet drastically affects vehicle reliability and cost of ownership.

In the light of the emissions compliance scandals legislators are now pushing for Real Driving Emissions (RDE) testing to reduce real world vehicle tailpipe pollutants (especially for NOx and particles from diesels).

Pollutant limits need to be set at stringent levels and there is an ‘introduction timetable’, allowing manufacturers some time to match the limits used in the laboratory on the road. This ‘conformity factor’ allows excursions from mandated laboratory emissions levels; initially more than double, but reducing over time, to laboratory test levels by 2025.

The EEC set deadlines and for diesel cars the maximum conformity factor was 2.1 x lab limits in 2018 and 1.5 x lab limits by 2020, but caved in when engine makers said they couldn’t do it.



No more car diesels


Many vehicle makers have now given up and the sub-two-litre diesel is the first casualty. It’s certain that there will be no such engines in the future.  European diesel car and SUV sales have dropped drastically since 2009, achieving only 16-percent market share in 2022 and are predicted to have only a five percent share by 2030.

“VW is debating whether it still makes sense to invest a lot of money in further developing diesel,” chief executive Matthias Mueller told the business daily Handelsblatt, back in June 2016.

Volvo CEO Hokan Samuelsson said that the carmaker will progressively replace its diesel engines over the next few years:

“The petrol hybrid is a very attractive alternative to a diesel engine, offering much lower CO2 levels, but with similar performance.

“Within a couple of years, the diesel will get more expensive and the hybrid system will get cheaper.”

Renault expected diesel engines to disappear from most of its European cars, a Reuters mid-2016 report stated. The French automaker reviewed the costs of meeting tighter emissions standards following the Volkswagen scandal:

“Tougher standards and testing methods will increase technology costs to the point where diesel is forced out of the market,” said a company spokesman.

Mercedes-Benz says it remains committed to diesel engines, but production of its new-generation modular in-line four- and six-cylinder engines can be switched from diesel to petrol fuel if buying patterns change.

Audi realigned its motorsport strategy, away from its dominant diesel-powered sports cars. VW-owned Audi terminated its FIA WEC commitment, including the 24 Hours of Le Mans, at the end of the 2016 season.

Speaking to Reuters about the future of petrol-electric and plug-in hybrids, Koei Saga, Toyota’s head of powertrain development, reiterated his company’s reservations about diesel: “It’s hard to see diesel becoming a mainstream solution,” he said.

Toyota is staying with petrol power in the US pickup market, despite extreme pressure for a diesel model from Tacoma buyers.

Toyota USA’s Mike Sweers said that while everybody loves diesel grunt in pickup trucks the downside is that after-treatment systems can add $3000-$5000 or more to the cost price. He didn’t believe that could be justified.

The new round of emissions laws in Europe and the USA requires manufacturers to make engines that remain compliant with emissions laws for up to five years and 160,000km:

‘In terms of in-service requirements under Euro 6, Regulation 15/2007 requires a manufacturer to check in-service conformity for all vehicles it certifies to the Euro 6 emission standards for a period of up to five years or 100,000km, whichever comes first.

‘Durability testing of pollution control devices undertaken for type approval shall cover 160,000km, the mileage over which these devices are expected to perform.’

Some countries are actively discouraging diesel. In August 2016, India’s National Green Tribunal (NGT) ordered the Road Transport Office (RTO) of Delhi to de-register all diesel vehicles over 10 years old and India’s roads minister has said that he wanted all cars to be electric by 2030. Norway and the Netherlands are banning the sale of all diesel-engined cars by 2025.

Surprisingly, Saudi Arabia is planning to establish a $US2 trillion sovereign wealth fund by selling off its state petroleum assets in preparation for a world beyond oil.



Electric replacements are coming fast


It’s obvious that the diesel emissions
crisis caused controlled panic in car makers’ boardrooms around the globe. Plans for hybrid and EV model launches have been fast-tracked and priority given to establishing EV charging stations, to speed-up public acceptance of EVs.

A joint venture (JV) between major European car makers was announced in late-November 2016. The signatories included BMW, Daimler, Ford and Volkswagen.

The JV covered the installation of a European network of EV-vehicle charging stations, with up to 350kW charging capacity per connection. That’s more than double the charging capacity of Tesla’s system and should drastically reduce overall charging times. (Tesla  developed an adaptor to suit this charging system.)

Initially, the JV aimed to set up 400 sites across Europe, with the rollout starting in 2017. The longer-term view is for thousands of such installations.

The charging technology is called Combined Charging System (CCS), which is a quick-charging method that uses a combination AC/DC connector, capable of delivering a maximum 350kW charging rate. This CCS standard seems to be globally accepted as the way of the future.

Only a few years year ago, a suggestion that European makers would be producing EVs and range-extended electric vehicles (REVs) in great numbers by 2020 would have laughed to scorn, but at the beginning of 2017 it was already happening.

Even in Australia there’s EV progress and BEV charging initiatives are being announced almost weekly, these days.





Is there any way to improve the reliability and emissions performance of diesel engines?

There were many initiatives, including opposed-piston engines, CO2 recovery technology, non-EGR engines, advanced combustion technology and other proposed systems, but none yet has proved to be the magic bullet that can give the internal combustion engine – diesel or petrol fuelled – a clean bill of health, without the use of expensive and troublesome injection equipment and exhaust after-treatment add-ons.

It may well be time for a complete shift from mechanical powertrains into into electric and electric hybrid powertrains.

Those who think that there’s no future for the electric vehicle should note that China racked up 150,000 EV sales in 2015; almost six million in 2022 and nearly eight million in 2023!

The best known electric vehicle maker is Tesla, which now boasts the largest-selling single car model in the world – outscoring Toyota’s Corolla.

However BEV SUV variants won’t work in Australia’s remote areas.

Another initiative is the fuel cell, using hydrogen fuel and an electric powertrain, but storage and distribution are major issues with hydrogen.

Where recent developments leave the traditional Australian-market 4WD is unclear.  We no longer have the capacity to produce a market-specific vehicle or powertrain here, so we’ll have to take what global makers dish up.

In the short term we’ll continue to live with troublesome diesels and far less tricky petrol engines. In the medium term it’s likely there’ll be parallel hybrid (electro-mechanical) powertrains.

Ultimately, the Aussie 4WD will probably be a series hybrid with a range-extending internal combustion engine or fuel cell, a battery bank and electric motors front and rear.

The EV arc has been struck, we think.






























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