Cont O-300D oil leak problem

[[email protected]]

I don't know what to do about this . . . hoping the collective wisdom
here might have some ideas. For the last 3 months or so, after every
flight, there are small streaks of oil on the inside of the lower
cowling on my 67 'Hawk . . . if I don't wipe them up, they drip down on
the tire of my nose gear. My mechanics have replaced all 6 rocker box
covers and gaskets, and re-flared the push rod tubes. I have spent
almost $1000.00 so far and it's still leaking. It holds pressure just
fine . . . my mechanics are now suggesting replacing all the push rod
tubes, but I get the feeling they are just guessing.
Any ideas?

www.Rosspilot.com

[Darrel Toepfer]

wrote:
> I don't know what to do about this . . . hoping the collective wisdom
> here might have some ideas. For the last 3 months or so, after every
> flight, there are small streaks of oil on the inside of the lower
> cowling on my 67 'Hawk . . . if I don't wipe them up, they drip down on
> the tire of my nose gear. My mechanics have replaced all 6 rocker box
> covers and gaskets, and re-flared the push rod tubes. I have spent
> almost $1000.00 so far and it's still leaking. It holds pressure just
> fine . . . my mechanics are now suggesting replacing all the push rod
> tubes, but I get the feeling they are just guessing.
> Any ideas?

There are some replacement spring loaded tubes that do a better job.
I'll have to dig up the info on them...

What gaskets did they use on the rocker covers? We had the good silicone
ones, but they needed to be replaced from over tightening, replaced the
covers as you did as well. Make sure the dipstick isn't leaking and how
much oil are you carrying? Its best kept under or at 7 quarts, if you're
keeping it topped off, that can make for a dirty cowling...

http://www.napanet.net/~arbeau/swift/cyl.htm
http://www.napanet.net/~arbeau/swift/o3006.htm

[Drew Dalgleish]

On 30 Nov 2005 17:07:17 -0800, " >
wrote:

>I don't know what to do about this . . . hoping the collective wisdom
>here might have some ideas. For the last 3 months or so, after every
>flight, there are small streaks of oil on the inside of the lower
>cowling on my 67 'Hawk . . . if I don't wipe them up, they drip down on
>the tire of my nose gear. My mechanics have replaced all 6 rocker box
>covers and gaskets, and re-flared the push rod tubes. I have spent
>almost $1000.00 so far and it's still leaking. It holds pressure just
>fine . . . my mechanics are now suggesting replacing all the push rod
>tubes, but I get the feeling they are just guessing.
>Any ideas?
>
>www.Rosspilot.com
>
Give the engine a real good cleaning then run it up shut down pull
the cowl and check with an ultraviolet light to spot the source of the
oil

[[email protected]]

<<What gaskets did they use on the rocker covers? >>

We replaced with the orange silicone gaskets, and torqued them to
specs.

<< Make sure the dipstick isn't leaking and how
much oil are you carrying? >>

Its definitely not the dipstick, and I carry between 6-7 qts. Last
Aug, during annual, I installed an Airwolf Separator . . . because I
was blowing out all but 6 and I wanted to maintain at least 7. That
definitely isn't the problem, either (according to mechanics). Thanks
for input.


www.Rosspilot.com

[[email protected]]

<<Give the engine a real good cleaning then run it up shut down pull
the cowl and check with an ultraviolet light to spot the source of the
oil >>

OK--will try the UV light . . . we didn't use that. They just used a
flashlight for visual inspection and fingers to feel for the wet spots
.. . .


www.Rosspilot.com

[Tri-Pacer]

<>I don't know what to do about this . . . hoping the collective wisdom
> here might have some ideas. For the last 3 months or so, after every
> flight, there are small streaks of oil on the inside of the lower
>

Has a similar problem when the oil leak seem impossible to find or fix.
It turned out that the crankcase vent tube had been repositioned so that it
pressurized the crankcase in flight.

Once moved---no more leak.

[RST Engineering]

Small streaks? SMALL STREAKS??? Man, you got one of the tight engines.
Most O300s drip more than they burn. The only reason Continental never got
into the computer business is that they couldn't figure out how to make the
computers leak oil.

I had a '64 for the better part of 15 years and never COULD completely
tighten that sucker up, even after I did a down-to-the-ground overhaul on
it.

Jim


> wrote in message
oups.com...
>I don't know what to do about this . . . hoping the collective wisdom
> here might have some ideas. For the last 3 months or so, after every
> flight, there are small streaks of oil on the inside of the lower
> cowling on my 67 'Hawk

[Brock Boss]

wrote:
> I don't know what to do about this . . . hoping the collective wisdom
> here might have some ideas. For the last 3 months or so, after every
> flight, there are small streaks of oil on the inside of the lower
> cowling on my 67 'Hawk . . . if I don't wipe them up, they drip down on
> the tire of my nose gear. My mechanics have replaced all 6 rocker box
> covers and gaskets, and re-flared the push rod tubes. I have spent
> almost $1000.00 so far and it's still leaking. It holds pressure just
> fine . . . my mechanics are now suggesting replacing all the push rod
> tubes, but I get the feeling they are just guessing.
> Any ideas?
>
> www.Rosspilot.com

After our overhaul and complete cylinder replacement we had a tiny dent
in one of the crush gaskets on the screw-on oil filter adapter that
produced a small leak. Replaced the gasket and have had a squeaky clean
O-300D since. Knock on wood!

[Kobra]

>. 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

[Carl Orton]

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
>
>
>

[Clay]

Clean the engine.
Run engine to operating temp.
Blow talc powder on the engine and look for the wet spot. Not as
glamerous as dye checking but effective.

[Jay Honeck]

> My mechanics have replaced all 6 rocker box
> covers and gaskets, and re-flared the push rod tubes. I have spent
> almost $1000.00 so far and it's still leaking.

You told your mechanic that you had an oil leak, and that he should go fix
it?

Whoo-eee...I'll bet he's had visions of sugar plums dancing in his head for
weeks! Talk about a license to steal...

Never, ever send an A&P on a fishing expedition. You'll only get hooked,
and everything will smell fishy...

;-)
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

[[email protected]]

>My mechanics have replaced all 6 rocker box
> covers and gaskets, and re-flared the push rod tubes. I have spent
> almost $1000.00 so far and it's still leaking.


Jay<<You told your mechanic that you had an oil leak, and that he
should go fix
it?
Whoo-eee...I'll bet he's had visions of sugar plums dancing in his head
for
weeks! Talk about a license to steal... >>

Not at all. I was there every minute, observing everything. I even
flew to Danbury (Coastal Aviation) to pick up the new rocker box covers
myself. I did the runups on the ramp after each attempt to fix it.
These guys were definitely not trying to exploit me, and they are just
as frustrated as me by the persistant leak. In fact, I am forwarding
all the comments from the NG to them at their request. They want to
fix it as much as I do.

<<Never, ever send an A&P on a fishing expedition. You'll only get
hooked,
and everything will smell fishy... >>

Sound advice, but this is not the case here. Thanks . . .


www.Rosspilot.com

[Jay Honeck]

> <<Never, ever send an A&P on a fishing expedition. You'll only get
> hooked,
> and everything will smell fishy... >>
>
> Sound advice, but this is not the case here. Thanks . . .

I know you didn't, Lee. I guess I forgot the little smiley thingy...

;-)
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

[[email protected]]

Small Continentals typically leak from both ends of the pushrod
tubes. The rubber couplings at the case need to be replaced, which
requires pulling the cylinders off, at which time the cylinder base
seals (o-rings) should be done, too. The head end of the tubes will
often leak until the rocker covers are removed, cleaning solvent (like
Brake and Parts Cleaner or laquer thinner) is used to flush out the
tube/head joints, and a wicking Loctite is run into them. If it's the
front crankshaft seal, there's a split version available to install
without any fuss.
The oil tank or accessory cover gaskets might be leaking, and
worst of all, the crankcase joint might be starting to seep.

Dan

[Newps]

wrote:
>>My mechanics have replaced all 6 rocker box
>>covers and gaskets, and re-flared the push rod tubes. I have spent
>>almost $1000.00 so far and it's still leaking.
>
>
>
> Jay<<You told your mechanic that you had an oil leak, and that he
> should go fix
> it?
> Whoo-eee...I'll bet he's had visions of sugar plums dancing in his head
> for
> weeks! Talk about a license to steal... >>
>
> Not at all. I was there every minute, observing everything. I even
> flew to Danbury (Coastal Aviation) to pick up the new rocker box covers
> myself. I did the runups on the ramp after each attempt to fix it.
> These guys were definitely not trying to exploit me, and they are just
> as frustrated as me by the persistant leak. In fact, I am forwarding
> all the comments from the NG to them at their request. They want to
> fix it as much as I do.

Well clearly there was more work done than new gaskets and some flaring.
The new gaskets are about $8 each if you get the good silicone ones.
Takes an hour to install them, at most.

[Newps]

If the pushrod tubes are the same as on the big bore Continentals then
the cylinders do not need to be pulled, you just need the tool to
compress the springs. And no mechanic worth the title uses loctite on
those tubes. If you get the gaskets in right they do not leak. Very
easy to tell with a little mirror.



wrote:

> Small Continentals typically leak from both ends of the pushrod
> tubes. The rubber couplings at the case need to be replaced, which
> requires pulling the cylinders off, at which time the cylinder base
> seals (o-rings) should be done, too. The head end of the tubes will
> often leak until the rocker covers are removed, cleaning solvent (like
> Brake and Parts Cleaner or laquer thinner) is used to flush out the
> tube/head joints, and a wicking Loctite is run into them. If it's the
> front crankshaft seal, there's a split version available to install
> without any fuss.
> The oil tank or accessory cover gaskets might be leaking, and
> worst of all, the crankcase joint might be starting to seep.
>
> Dan
>

[nrp]

> If the pushrod tubes are the same as on the big bore Continentals then
the cylinders do not need to be pulled, you just need the tool to
compress the springs. And no mechanic worth the title uses loctite on
those tubes. If you get the gaskets in right they do not leak. Very
easy to tell with a little mirror. <

The O-200/O-300 engines have the pushrod tube swaged into the cyl head
assembly. There is an elastomeric seal at the crankcase end only. I
understand there is a re-swaging tool that I assume you already have
used to tighten these joints, but that tool can only do so much before
it damages the tubes etc. The use of loctite is appropriate.

I thought someone had mentioned it earlier (maybe on another post?) &
I've never tried it, but perhaps you could pressurize the crankcase
thru the breather line to maybe 1-2 psi & do soap bubble tests. Don't
go any higher or you would probably blow out the front crankshaft seal.
BTW I assume the front seal has its split in the correct quadrant?

Chances are otherwise pretty good the leak is around one of the case or
pan splits, in which case a vaccum should be used to suck in a sealant
after cleaning.

[[email protected]]

After six years trying to figure out were the leak came from and after
many thousands of dollars spent. My O-300 is still leaking the same,
one quart every four hours of flight. I believe I can live with that.
The best option to solve this problem I believe is to replace the
engine with an O-360.

[Dave Stadt]

> wrote in message
oups.com...
> After six years trying to figure out were the leak came from and after
> many thousands of dollars spent. My O-300 is still leaking the same,
> one quart every four hours of flight. I believe I can live with that.
> The best option to solve this problem I believe is to replace the
> engine with an O-360.

I find it impossible to believe a 1 quart per 4 hour leak cannot be found.
A leak that major would coat the entire fuselage in minutes. A tablespoon
of oil can spread over a very large area and make it seem like a major leak.
I assume you took it to several A&Ps over the six years.

[[email protected]]

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.

[clipclip]

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

[Darrel Toepfer]

clipclip wrote:

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

Contact Adhesive aka Superglue

[[email protected]]

wrote:
> I don't know what to do about this . . . hoping the collective wisdom
> here might have some ideas. For the last 3 months or so, after every
> flight, there are small streaks of oil on the inside of the lower
> cowling on my 67 'Hawk . . . if I don't wipe them up, they drip down on
> the tire of my nose gear. My mechanics have replaced all 6 rocker box
> covers and gaskets, and re-flared the push rod tubes. I have spent
> almost $1000.00 so far and it's still leaking. It holds pressure just
> fine . . . my mechanics are now suggesting replacing all the push rod
> tubes, but I get the feeling they are just guessing.
> Any ideas?
>
> www.Rosspilot.com

I agree with Kobra. I went through the same thing with my 0-300 and was
able to confirm (with great effort I might add) that the through bolts
are leaking. My mechanic confirmed that the 'O' rings in the case
halves do harden with age and the holes terminate outside the cylinder
seal. This is where the oil leaks, from under the cylinder at the
bolts. Looks like the push rod tubes and will drive you crazy. Since
giving up I am OK with flying a drippy plane. Keeps the belly from
corroding I figure. I have found that the absolute best way to find
leaks is the dye that shows up under a 'black light' (the ones that
glow yellow are my favorite) after a through cleaning. I seem to
remember the stuff being available on Ebay.

Jim

[Mark Hansen]

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

[[email protected]]

>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

[George Patterson]

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.

[George Patterson]

wrote:

> I seem to remember the stuff being available on Ebay.

NAPA also used to sell it.

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