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Spark
plug boot is changing color |
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Spark
plug boot is changing color |
This wire is from a Toyota Corolla
with a 16 valve DOHC engine. The spark plug wire shown above is
from an original equipment set, sent to us because a problem with
the wires was suspected.
Diagnosis by automotive technician:
Faulty wires
Diagnosis by Magnecor:
It is obvious, by the discoloration of the bottom seal on
the spark plug connector that water, and some oil, was collecting
in the spark plug hole in which this connector was situated. The
water level (which causes the spark plug base to rust) had
reached the connector seal. Spark plug wire connectors are not
designed to operate under water, and on this vehicle spark arcing
into water no doubt occurred, causing the engine to misfire.
Engines in cars suffering the problem of water filling spark plug
holes will develop an engine miss at times whenever spark energy
finds it easier to track down spark plug porcelain (inside the
connector seal) and into the water. Also, arcing into water will
occur after a pin hole is burnt through the connector's plastic
extension tube, particularly if spark plugs gaps are too wide due
to erosion or adjustment. Any trace of engine oil
(leaking from valve cover) in spark plug holes will make matters
worse! Not all spark plug holes will be affected.
Any spark plug wire connector, boot or seal which changes
color indicates that water, engine oil, or a combination of both
is present in the spark plug hole. If nothing is done to remove
the water/oil from the spark plug hole/s, the engine will develop
a misfire, and the wire connector/s will eventually be destroyed.
Suggested remedy:
In cases like this, often all that has to be done is to
clean out all the moisture and sometimes replace (if it appears
contaminated with rust) the seal that fits over the spark plug
(which are available from Magnecor as spare parts, even for many
original equipment wires). Sometimes a thin smearing of silicone
grease around the spark plug porcelain to help seal from moisture
can help and replacing the spark plugs (particularly if they are
old or the gaps are large) is also a good idea. Often replacing
the wires is the simplest and the easiest fix, but you still have
to make sure you deal with any moisture, oil or spark plug gap
problem or the new wire, in time, will also fail for the same
reason.
More information relating to this subject is available on our
FAQ, specifically:
