Wheels Australia - June 2018

@wheelsaustralia 27

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ation for why

licting the

rd: emissions. It

quick fix, where

ilated via the oil

soaked crankcase, then back through

the Exhaust Gas Recirculation (EGR)

valve, where they return to the intake.

Positive crankcase ventilation, they

call it. It’s a form of automotive second

hand smoking where the engine

rebreathes some of its old fumes in a

bid for a more complete burn-off of

harmful emissions.

“The engine breather is supposed to

vent crankcase gases but unfortunately

it also brings oil with it and the turbo

endorses that by punching it straight

through to the intake. Then you’ve got

the EGR valve open on cold starts, so

there’s some unburnt fuel going through,

plus the oil. The result is black liquid

glue,” says Frank Spiteri, the senior

partner in his father and son Bosch

service operation in Sydney’s Milperra.

A booming aftermarket fix is the

fitment of a so called ‘catch can’

to harvest oil from engine blow-by

before it hits the intake system. Why

manufacturers don’t fit these as

standard is an open question. Cost

is the most likely answer and as the

problem doesn’t always make itself

obvious during the warranty period

... well guess the rest.

The more radical fix is also the illegal

one – to blank off the EGR system.

“The EGR technology is up for debate

but no one wants to do it for fear of

government prosecution” says Berrima

Diesel’s Andrew Leimroth.

“It cannot be blocked off legally but

installing a catch can may keep the inlet

manifold slightly less oily and not allow

the carbons to stick as much” he says.

Downstream from the engine, the

problems become even more expensive.

INTAKE PORTS COATED IN

CARBON BUILD-UP CAN BE A

MAINTENANCE NIGHTMARE

Manycarsaresufferinganautom
formofcloggedarterieswithcar
soot and oil deposits clagging int
manifolds, coating sensitive exh
gasrecirculation valves and jam
turbo actuatorflaps. Less than
60,000km is required in some ca
to coke up modern high-pressur
common-rail diesels in a maint
nightmare reminiscent of thev
grind and decoke requirements
1950s engines.
Result:routinelya$3000billt
dismantle the intake system, re
thethick gunk and reassemble
aloneis10+hours.
Left untreated, the fall off in
emissions performance and fu
economyisanopenquestion.
Wheelscanfindlittleevidenc
manufacturer servicing sched
anyrequirement to decarboni
systems. Indeed any formalad
owners about the problem iss
Weknow because we askedth
provideit.
Atbest, local dealers offer$
“magic spray” treatments, wh
expertssaymay–ormaynot
some preventative benefit bu
unclog centimetres-thick slu
“Even if it removes someo
whewhere s it going? asks onere’s it going?” a k
mechanic. “If it doesn’t get
the backofthe valvesort
head itwilllodge intheD
otherproblems.”
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