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Is
there more than one type of gasket sealant, and if so, what are the differences
between them, and how are they applied? J.P., via e-mail
There are two
types of gasket sealant commonly used: room temperature vulcanizing (RTV)
and anaerobic. Both come in tubes, but each has different sealing properties,
so they’re not interchangeable.
RTV
is cured by moisture in the air, so the cap must always be put back on
the tube as soon as possible. It has a shelf life of about one year, so
always check the expiration date on the tube before you use it. If there
is no expiration date on the tube, don’t buy it.
When
using RTV sealants, first remove all residue, dirt, and oil from the mating
surfaces. Make sure to remove any gasket material from the blind attaching
holes, which are used to position those parts, as it can cause hydraulic
lock and prevent the bolts from properly tightening the parts.
Unless
otherwise specified by your engine manufacturer, apply RTV sealant in
a continuous bead of 1⁄8 to 3⁄16 inch thick, and apply sealant
to the bolts where they contact the top of the head, as well as to the
threads. Torque the bolts within 15 minutes after applying the sealant
or it will have already started to cure and not seal properly. If this
happens, you’ll have to remove the old sealant, reclean the surfaces,
and redo the process.
Anaerobic
sealant cures only in the absence of air, as when it’s squeezed
between two machined mating surfaces, so it will not spoil if the cap
is left off the tube. It should not be used if one of the mating surfaces
is flexible.
As with
applying RTV, first clean gasket material, grease, and dirt from the mating
surfaces, and remove any gasket material from blind attaching holes. Unless
otherwise specified, apply the material in a continuous bead no less than
1⁄3 inch to one sealing surface, as well as to the bolts where they
contact the head and bolt threads. As with RTV, you should torque the
bolts within 15 minutes of application or the sealant will start to cure.
I
am considering upgrading to a larger battery charging system. Will I have
to change my wiring? S.L., via e-mail
Unless you
are a qualified electrician, it is best to leave this to the experts.
However, even if you have the job done by a pro, you should be aware of
some basic principals.
First,
rewire when upgrading to a larger battery charger. If you use the same
gauge wire as on your existing system and subject it to a heavier load,
the result will be increased resistance, which reduces voltage and produces
more heat and, in the extreme, fire. The U.S. standard for wire size is
the American Wire Gauge, or AWG. The higher the number, the smaller the
diameter; a #18 gauge wire is smaller than a #10 gauge wire. Your electrician
can determine the proper gauge wire for you.
Also
consider the length of the wire run. Long runs typically result in lower
voltage due to increased resistance. A three-percent drop is fairly normal
with long runs, so although your charging device may be set to the normal
charging voltage of 13.8, your batteries will receive only 13.4 volts.
That’s why you should install the charger as close to the batteries
as possible. (Remember, if the battery is 15 feet from the charger, the
total run for both wires will be 30 feet.)
Need
help with a maintenance problem? Write to Maintenance Q & A, Power
& Motoryacht, 260 Madison Ave., 8th Fl., New York, NY 10016. Fax:
(917) 256-2282. e-mail: ken_kreisler@primediamags.com.
No phone calls, please.
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