Cont O-300D oil leak problem

At my most recent annual a few weeks ago, we tightened up the through bolts.

BIG diff in the quantity of oil drips.

Still have 'em, but drastically reduced.


"Kobra" wrote in message
...
. my mechanics are now suggesting replacing all the push rod
tubes, but I get the feeling they are just guessing.
Any ideas?

crack in the crankcase, leaking at the through-bolts are options.

Kobra

Well, I guess tightening up the through-bolts is OK, as long as you
don't over-torque them.

I just rebuilt an O-300 and have worked on several of them. They are
great engines, though at 145HP and 7 to 1 compression not behemoths of
power. Crush washers on the rear case and on the oil sump are bad to
leak, if they have been over-used. Buy new ones; they're cheap anyhow.
Sometimes you'll have a leak on the rear case where a stud has been
pulled loose from the magnesium housing, like at the seal cover for the
tach drive.

I see a lot of leaks around the pushrod-tube-to-crankcase boots, which
are easy to get off their seats or not have their spring clamps seated
properly. Those boots are tough and will last to TBO, but sometimes
you'll have to adjust one to get it to do its work.

To find a leak I always clean the engine and fire it up with the cowl
off. Run it just long enough to get the oil warm and don't fry your
cylinders. Leave your aircraft on the ramp so you can see where it's
dripping. Invariably we have found our culprit leak and been able to
stop it.

I always paint gaskets like valve cover gaskets, and all the other
gaskets, with High-Tack, front and back. If you get any leak around
any of those gaskets the oil will be dyed red by the High-Tack, so you
know generally where it's coming from.

Of course, CA glue is great for stopping seepage around bolts and seams
in the case. Put a vacuum cleaner to the oil filler and apply the
glue.

Finally, if people would handle cylinders gingerly and not hold them by
their pushrod tubes, the damn things wouldn't leak. Having to use
that beading tool to seal the tubes inside the cylinder head just means
the cylinder was abused by someone.

Originally Posted by

Of course, CA glue is great for stopping seepage around bolts and seams
in the case. Put a vacuum cleaner to the oil filler and apply the
glue.

----------------------

maybe everyone besides me knows this, but what is "CA glue" - CyanoAcrylate glue?

TIA,

frank

clipclip wrote:

maybe everyone besides me knows this, but what is "CA glue" -
CyanoAcrylate glue?

Contact Adhesive aka Superglue

On 12/4/2005 6:36 AM, Darrel Toepfer wrote:

clipclip wrote:

maybe everyone besides me knows this, but what is "CA glue" -
CyanoAcrylate glue?

Contact Adhesive aka Superglue

Ummm, CA stands for Cyanoacrylate. It comes in different viscosities,
basically thin, medium and thick (and possibly others?).

--
Mark Hansen, PP-ASEL, Instrument Airplane
Sacramento, CA

Darrel Toepfer wrote:

Contact Adhesive aka Superglue

Contact adhesive is completely different from Superglue. Superglue is a brand of
cyanoacrylic glue. Contact adhesive is more viscous and resembles thin rubber
cement. You apply a thin layer to two surfaces, let it dry, and put the surfaces
together. It bonds as soon as the surfaces make contact; hence, the name. It's
used for things like applying plastic laminate to substrate material for
countertops.

George Patterson
Coffee is only a way of stealing time that should by rights belong to
your slightly older self.

Finally, if people would handle cylinders gingerly and not hold them by
their pushrod tubes, the damn things wouldn't leak. Having to use
that beading tool to seal the tubes inside the cylinder head just means
the cylinder was abused by someone.

Amen to that. However, the aluminum head expands at twice the rate of
the steel tubes (the coefficient of linear thermal expansion) and this
tends to leave the tubes a little loose when things are hot. I don't
know if Continental relied on the metal-to-metal seal when they
manufactured them, or if there was some sort of sealant used that
crumbles or disappears with age. That's why I use the Loctite, after
the cylinders are installed so that the tubes won't be moved anymore,
and the Loctite, being plastic and having a much larger expansion rate
than even aluminum, keeps things sealed up all the time. Loctites reach
their maximum strength at around 300 degrees, too.

Dan