28 whichcar.com.au/wheels
Three rapid-fire developments from the cradle of the
German car industry pose big questions for the future of
diesel power.
We know about Volkswagen’s fudging of emissions
tests, an event that so far has cost it more than
$US26 billion and is still being fought in courtrooms
around the world.
The retrospective ‘fix’ is blunting fuel economy
and performance, according to recently
published, independent Australian tests.
Volkswagen contends this point.
In February a German court ruled the
unthinkable was possible – a ban on
driving all diesel cars in Stuttgart,
home of Mercedes-Benz.
Earlier, it was rumoured another
Stuttgart powerhouse brand, Porsche,
would soon cease production of all diesel-
powered models, a move the brand has since
officially denied.
The common element in all three events is the
thermodynamically efficient diesel engine’s Jekyll & Hyde
emissions profile.
Globally, carbon dioxide (CO 2 ), a.k.a. a greenhouse gas, is the big
climate change issue. Carbon dioxide, essential for life on earth, is
routinely misreported as a ‘pollutant’.
The good news is diesel engines produce much lower levels of CO 2than petrol engines. This earns
plenty of green kudos and labels
like ‘clean diesel’ – at least before
the VW scandal.
The bad news is diesels emit
high levels of nitrogen oxides (NOx)
including the toxic nitrogen dioxide
(NO2 ), greenhouse gas nitrous oxide
(N2O) and nitric oxide (NO), which reacts
with oxygen to form the fine particulate
matter that diesel engines produce.
These micron-fine particles of carbon soot
are so small they can lodge in the lungs and are
known carcinogens.
VW admits to cheating the NOx tests and there
is no doubt that the pollutant is a key contributor to
air quality.
That’s why NOx is such a big local air-quality issue,
along with particulates, in cities like London, Los
Angeles and now Stuttgart.
The spiritual birthplace of the car, Stuttgart, exceeded
safe pollution levels on 45 days in 2017, down from 63
the year before but still above the European Union’s
requirement of no more than 35.
With roughly one in three German vehicles powered by
a diesel engine, the ruling is a massive wake-up call for
the industry.Diesel particulate filters are
designed to burn off harmful
nitrogen oxides and other tiny
particle emissions at blast
furnace temperatures, leaving
only an ash residue. No doubt this
stuff is better incinerated than
lodging in the lungs, given these
microscopically fine soot particles
are known cancer triggers.
Manufacturers claim the filters
are lifetime components, similar to
the catalytic converter.
“Under Australian conditions,
there’s not a hope in hell,” says
technician Bryce Spiteri, who sees
clogged, inoperative DPFs on a
daily basis.
Replacement costs for these
alleged “lifetime” diesel particulate
filters can be eye-watering: $4000
to $6000 is not uncommon. And
the end cost to the customer
typically doubles to $8000-$12,000,
when diagnostics, plus removal
and replacement labour charges
are added.
Many DPFs are failing just out
of the warranty period at around
100,000 kms but too often, much
sooner. This is very early in the
lifecycle of an old technology,non-common-rail diesel engine.
Typically those engines would
routinely deliver three times
that distance without major
maintenance.
Failed DPFs share some common
traits. “It can be spasmodic,” says
Spiteri. “Some of it is age and the
failure rates go up with kilometres
travelled. We see DPFs with a lot
of accumulated soot and ash and
even the passive regenerations
aren’t enough to clean them out
while driving. They get to the stage
where they are blocked and have to
be physically removed.”
Alarmed at the growing
number of DPF failures through
his workshop, Frank and Bryce
Spiteri began development of an
ultrasonic cleaning process that
could clean out many blocked
filters declared dead by dealer
service departments. It took three
years and $300,000 in investment,
but his company, DPF Regen, is now
bringing filters back from the dead
in a couple of days for under $500 a
pop. Plus labour.
Business is booming alongside
their existing Bosch Service centre
drawing business from brandeddealerships as well as truck and
bus companies.
The European marques can
generally be resuscitated, Frank
Spiteri says, and make up 70
percent of his throughput.
But many makes are deemed
throwaways.
He is seeing a lot of Holden
Captivas and Nissan Navaras that
fit that description but also a lot
of DPFs with the back end blown
out, the result of dealership service
departments repeatedly trying
what’s called a forced regeneration.
“They don’t even know how tomeasure differential back pressure,
so they try forcing the regeneration
repeatedly. One told us they’d tried
six times. Well, the thing just
melted.”
Bryce Spiteri adds BMW’s
embedded onboard data suggests
a service life of 250,000km for the
DPF in an X5.
“That might be right in Germany
where you are on the autobahn
at 130 kays for an hour each way
but those aren’t typical Australian
conditions” he says.
He has seen them blocked as low
as 60,000km under our conditions.Filter fail
End of the road for diesel?
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