NGK PKW Katalog 2012-2013

Ceramic glow plugs
As opposed to a metal rod glow
plug, the heating coil of a ceramic
glow plug has an especially high
melting point. It is also sheathed
in silicon nitrite, an extremely
rugged ceramic material. The
combination of the heating coil
and ceramic sheath enable higher
temperatures and extremely
short preheating times due to
excellent thermal conductivity.
Also, ceramic glow plugs have
a more compact design. This
is important, because there
is very little free space in
today’s engines. In an SRC
(Self Regulating Ceramic) glow
plug the heating element is
made of ceramic with a sintered
metal heating coil. An HTC
(High Temperature Ceramic) or
NHTC (New High Temperature
Ceramic) glow plug has a heating
element and a heater made
of ceramic.
The NHTC ceramic glow plug was
specially developed by NGK to
enable automobile manufacturers
to comply with the Euro 4 and
Euro 5 emissions standards. One
of the goals of these standards is
to reduce the compression ratio in
diesel engines. NHTC glow plugs
reach a temperature of 1,000 °C
in less than two seconds and
can after-glow for more than
ten minutes at temperatures
of up to 1,350 °C. Optimal
combustion is assured even
with low compression ratios. In
addition, the NHTC glow plug
can glow intermediately to
prevent cooling of the particle
filter in deceleration phases.
Ceramic glow plugs:
the technical optimum
For more than 20 years
automobile manufacturers have
been using NGK glow plugs as
standard equipment. But can
these glow plugs be replaced with
comparatively less expensive
metal glow plugs?
IS
19
The answer: many things “can” be
done, of course. The question is,
what risk is involved. In cars that
have NGK ceramic glow plugs
installed at the factory, only NGK
ceramic glow plugs should be
used when it comes time to
replace the glow plugs.
The reason: These glow plugs
were developed in-house for the
respective engines. Ceramic glow
plugs from NGK guarantee a long
service life and ensure a reliable
and fast ignition, even at the
lowest outside temperatures.
At the same time, they reduce
harmful emissions. Although they
at first appear to be somewhat
more expensive than metal glow
plugs, one should consider the
following: Metal glow plugs can
make it difficult to start a car at
extremely cold sub-zero
temperatures.
Tip!
When changing to metal glow
plugs, all of the glow plugs have
to be replaced, including those
that are intact.