Slipstream - December 2010

Tech Corner
Ed Mullenix, Tech Chair
Last month’s topic was electrical
system maintenance. I will
expand on that subject briefly and
then touch on the subject of storing your
Porsche for an extended period.
I have seen several articles on the various
threads about battery tenders (low current
battery chargers) and cut-off switches. If
you drive your Porsche every day or at least several times
during the month, you probably don’t need to worry about
it starting as long as the battery and charging system are
in good condition (re: last month’s column). If you have a
special car that only gets exercised occasionally
and only during nice weather, you might
consider one of the aforementioned items.
A battery cut-off switch is a heavy-duty
switch that you connect to your Porsche’s
battery ground cable. It usually has a red
plastic lever/key that turns the switch on and
off and is removable should you choose to do so
(great idea if you’re worried about your teenager
sneaking the car out
while you’re away,
bad idea if stuff gets
misplaced in your
garage). With a
battery switch turned
off, the static current is no longer an issue. You also lose
all of your radio preset stations or seat positions because
the memory power is disconnected. If your battery is fully
charged and you turn the battery switch off, you can come
back in several weeks and turn it back on and the car should
start. If you plan on not driving the car for several months,
a battery tender would be a better choice. Even when fully
charged and with no current drain (as in sitting on the shelf in
a parts store) an automotive lead-acid battery will discharge
after several months. A battery tender is connected to the
battery as one would any battery charger. A tender only
generates one to two amps of current so there is no worry
about overcharging. If you choose the battery tender and
leave the trunk lid open, remember to disconnect the trunk
light and micro-switch on the trunk latch. You can employ
both options and not have to bother with the trunk light,
etc. The battery tender requires that you leave it connected
to an extension cord plugged into a wall receptacle in your
garage. I have seen several cars that had a tender installed,
the trunk lid was closed, and the cord was not visible. The
result was the tender was ripped out by the roots when the
driver failed to disconnect same and drove away.
In addition to the battery issue, if you are not going to
drive your Porsche for several months there are some other
considerations as well. I had the opportunity several years
ago to place my car in long term storage when I won an allexpense
paid vacation to Iraq via the Navy! Here in Texas
we usually do not have harsh winters with months of rain
and snow. If your car is parked in a garage that protects
it from rain and cold, you don’t absolutely have to top off
the fuel tank. Moisture condensation inside a steel fuel
tank will cause rust formation. The less steel exposed to
moisture-laden air (as in full of fuel), the less possibility
of rust formation. I would recommend that you have
your oil changed shortly before you store your car. Any
combustion engine produces all sorts of weird
compounds that become acids in the presence
of water. For you non-chemistry majors,
the combustion of a gallon of gasoline will
produce more than a gallon of water. Most
of it goes out the exhaust but some finds its
way past the rings into the engine oil where
it combines to form acid (bearing-destroying)
compounds. Fresh oil has sufficient corrosion
inhibitors to prevent any corrosion for several
months. Brake fluid
absorbs moisture from
the air. If you’ve had
the brake fluid changed
within the past year, I
would not be too concerned
about it but I would get it changed when I returned the car
to service. Next, tire pressure. The tires are not perfectly
sealed to the wheels which is why we periodically have to
correct our tire pressure. Increase the tire pressure to around
45 psi. before storage to account for the slight air loss.
Lastly, rodent damage. I live next to a creek and from time
to time, I see evidence of little visitors in my garage. I place
trays of rat poison in my garage to give them something
to eat besides the insulation on my car’s wiring. Not sure
why, but there is something about the insulation on German
wiring that is irresistible to rodents. I have dogs (four at last
count) so I have to be careful where I place the poison.
Because Maverick Region encompasses the entire metroplex,
we will be having a tech session on the west side of
DFW at Autobahn Porsche. The Tech Session at Autobahn
Porsche will be on January 15th. Primary topic will be
brake system maintenance. We will discuss how driving
habits affect brake wear and have some training aids (worn
brake components) to illuminate when and why servicing is
required.
Ed
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