I use silicone gasket former/sealer (Permatex high-heat brown in the tube
sized for a caulking gun) on pretty much every component that requires a
paper, cork, or composite gasket. This is because, IMHO, it provides
superior sealing over the use of a plain/dry gasket or the glue/hi-tack
type adhesives, particularly in the corners or joints where multiple
gaskets come together (such as the oil pan on a Midget 1500 or the intake
manifold on a small block Chevy). I use it on oil pans, valve covers,
water pumps, thermostat housings, timing covers, engine plates, and
ancillary components in addition to the gasket.
Further, it has been my experience that it eases removal, and allows the
gasket to be 'saved' if the component is one that is removed
occasionally. Clean up of the surface is simply a matter of spritzing it
with carb cleaner and rubbing a cloth with carb cleaner sprayed on it
over the material or gasket mating surface. The old silicone rubs right
off, as well as any grease or oil.
The key is to use it *sparingly*. As Les Myer noted, it can squeeze out
and be released inside the engine where it can and will block oil
passages, pickups, etc. I first apply a *thin* even coat of the sealer
to the surface of the piece to be joined to the engine (for example, the
oil pan), lay the gasket into place, and allow it to set up while being
pressed into place (turn the thing upside down on a clean flat surface
and apply some weight to the turned up side). Once it has partially
dried, I flip it back over and remove the excess sealer, apply a *thin*
even coat of sealer to the gasket surface and let it become tacky (to
partially eliminate slipping when put into position), and install the
piece. Once dry, and before the engine is painted (if applicable), I run
an razor blade around the exterior edge to remove any sealer that
squeezed out.
For pieces I know I am going to have to remove later, such as the valve
cover on a car with solid lifters, I glue the gasket into place on the
valve cover, set it on a clean flat surface, weighted it down, and let it
dry. The gasket-to-block surface is left dry when installed. However,
since the surface of Miss Molly's 1500 head is flat (no raised gasket
ridge), I did put a *thin* even coat of sealer on the gasket-to-block
surface as in the previous paragraph before installing it. I've had it
off three times since then, and reinstalled it the same way each time.
No problems removing it, or cleaning the surfaces.
I also use it when installing steel frost/block plugs by roughing up the
back side slightly on the wire wheel and smearing a *very* thin coat on
it and the mating edges (but not on the block) to provide an additional
measure of protection against leaks and rust through. No incidents of
either on approximately twenty-five engines over 15 years.
I have had great luck with the ultra-high temp 'copper' sealer made my
Permatex. My '75 Monza kept burning out the header gaskets on its small
block regardless of the type of gasket used, or how often I checked the
bolts. I finally ended up replacing the gaskets with a new set, and
coating both surfaces with this sealer -- no more problems (though I
still checked the bolts regularly). I also used this stuff to seal the
header Y pipe joint where the weld had a hole in it. Though it makes me
a DPO in regards to that particular car, I never did go back and fix the
thing properly as it held up well for two years and several cross-country
trips (in my defense, I did point it out to the subsequent owner, and
told him he really should pull the header and braze it closed).
This all is, of course, only in my humble experience and opinion. Your
mileage may vary. However, Miss Molly doesn't leak oil or fluids.
Rich
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