Oil leak spotted around push rod tube seals

Sigh Nine hours now on the newly rebuilt Continental IO-520 with
Superior Millennium cylinders, and already the primary fuel pump is going
back to the company for repair or replacement. More importantly, oil is
escaping from the #2 and #5 cylinders' push rod tube seals (at the
Continental case end, for those like me who thought it was a cylinder
issue).

My mechanic told me that, in his experience, Continental is known for
problems with these seals.

Anyone have any experience with leaking push rod tube seals?

Granted all of this is covered under warranty, but after three and a half
months down, I wanted nothing more than to fly the wings off this aircraft
now that the engine replacement work has completed.

--
Peter













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I had what I thought was the same problem with my 0-300D. Thought it was the
seals but now I'm pretty sure its the lower center stud/nut holding the suspect
cylinder to the case. Looks like it leaks through the stud to the outside of
the cylinder o ring then down between the cylinder base and case, right on top
of the pushrod tube seals. I'm thinking that the stud needs to be sealed before
installing the cylinder. Anyone have any thoughts on this or have I just lost
it?

Jim

Anyone have any experience with leaking push rod tube seals?

Actually, EVERYONE has experience with leaking push rod tube seals.
Not everyone realizes it, though.

Seriously - as long as it's not leaking much and you can be confident
the oil is actually coming from there, it's not a big deal. On
Lycomings, the pushrods are on top so there's no way to mistake a leaky
pushrod seal for anything else. It's not really that they leak any
less than the Continentals, it's that the leaks are generally ignored
since they have no real safety consequences. On a Continental, it's on
bottom. The advantage is that the camshaft gets properly lubricated
(unlike a Lyc) but the disadvantage is that the pushrod tubes are a
pain to get to, and it's very easy to confuse a relatively benign leak
(pushrod tube seals) with a nasty one (leakage at the base of the jug,
for example). Since you don't want to mask a dangerous leak, you need
to fix the trivial one.

If it's really the pushrod tube seal that is leaking, it's not a
cylinder or a case issue - it's either a bent/cracked/otherwise damaged
lip on the pushrod tube (usually damaged during assembly) or a damaged
seal (also usually damaged during assembly). The oil there is not
under pressure, so there should not be much of it leaking. It's a very
minor problem in terms of parts and labor, and really you could fix the
problem yourself in 30 minutes by straightening/smoothing the pushrod
tube (if necessary) and replacing the seal (which I think costs about
$3).

Michael

Did you use the TCM seals or the Superior seals?
There is a difference.


"Peter R." wrote in message
...
Sigh Nine hours now on the newly rebuilt Continental IO-520 with
Superior Millennium cylinders, and already the primary fuel pump is going
back to the company for repair or replacement. More importantly, oil is
escaping from the #2 and #5 cylinders' push rod tube seals (at the
Continental case end, for those like me who thought it was a cylinder
issue).

My mechanic told me that, in his experience, Continental is known for
problems with these seals.

Anyone have any experience with leaking push rod tube seals?

Granted all of this is covered under warranty, but after three and a half
months down, I wanted nothing more than to fly the wings off this aircraft
now that the engine replacement work has completed.

--
Peter













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Fly wrote:

Did you use the TCM seals or the Superior seals?
There is a difference.

I learned today that the engine rebuilder told my mechanic that he used
Superior seals. As a result of this, the rebuilder is pretty "miffed" (to
use his words) to hear of this problem since the Superior seals are
supposed to be higher quality.

As Michael pointed out, though, perhaps it is not these seals that is
causing the leak. The rebuilder did ask the mechanic to again clean
everything up to be absolutely sure the oil is coming from the push rod
tube seals.

He also asked the mechanic to roll the push rods 180 degrees and to use a
screw driver to tab the seals to ensure they are seated properly (perhaps I
am not explaining the troubleshooting techniques correctly, but I am
confident the rebuilder explained the correct technique to the mechanic).

--
Peter













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Michael wrote:

If it's really the pushrod tube seal that is leaking, it's not a
cylinder or a case issue - it's either a bent/cracked/otherwise damaged
lip on the pushrod tube (usually damaged during assembly) or a damaged
seal (also usually damaged during assembly). The oil there is not
under pressure, so there should not be much of it leaking. It's a very
minor problem in terms of parts and labor, and really you could fix the
problem yourself in 30 minutes by straightening/smoothing the pushrod
tube (if necessary) and replacing the seal (which I think costs about
$3).

Thank you, Michael, for the explanation. Being that this is all under
warranty, however, I will leave the fix to the experts.

--
Peter













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JFLEISC wrote:
I had what I thought was the same problem with my 0-300D.

FYI - If by chance the leak is between the upper end of the pushrod
tube and the cyl head, there is only a metal-to-metal seal between the
two. For field repair, a multi-ball type expander tool is used to
expand a bead from the ID of the tube to get it to reseal. Sometimes
the tubes get loose during misc jug handling. It is a simple fix when
you find someone with the tool.

But you are smart to be absolutely certain where the leak is first.

On Tue, 8 Feb 2005 15:57:23 -0500, "Peter R."
wrote:

Sigh Nine hours now on the newly rebuilt Continental IO-520 with
Superior Millennium cylinders, and already the primary fuel pump is going
back to the company for repair or replacement. More importantly, oil is
escaping from the #2 and #5 cylinders' push rod tube seals (at the
Continental case end, for those like me who thought it was a cylinder
issue).

My mechanic told me that, in his experience, Continental is known for
problems with these seals.

It's not Continental's fault, it's the way they were installed.
If the seal is actually leaking and the tube is OK, it's more than
likely the edge of the seal (inside or outside) was rolled as it or
the tube was pushed into place.

I had two that were leaking like crazy after a top (soft rings). One
mechanic just couldn't seem to get them right. The Bo specialist at
HTL only took a few minutes to fix them right.

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com

Anyone have any experience with leaking push rod tube seals?

Granted all of this is covered under warranty, but after three and a half
months down, I wanted nothing more than to fly the wings off this aircraft
now that the engine replacement work has completed.

Had the same leak at about 200hrs on an IO-550-B. Fixed at annual.

--

Thx, {|;-)

Victor J. (Jim) Osborne, Jr.



take off my shoes to reply

It's funny you wrote this when you did. I had a different mechanic take
a look at all my leaking pushrod tubes this week. The main problem is
the seals don't get inserted right. After watching him do it there
really is no excuse. You can see all you need to see with a flashlight
and a mirror. You could clearly see where my seals didn't get seated
properly. It doesn't matter which of the two seals you use, they are
the same. My last mechanic used permatex on the seals. Don't. The new
guy puts vaseline on the edges so they seat properly. He also doesn't
use the special tool for the springs, doesn't like it. After
compressing the spring he uses safety wire to hold them in position.
After tube is in place he snips the safety wire and the spring snaps
into place.

Peter R. wrote:

Sigh Nine hours now on the newly rebuilt Continental IO-520 with
Superior Millennium cylinders, and already the primary fuel pump is going
back to the company for repair or replacement. More importantly, oil is
escaping from the #2 and #5 cylinders' push rod tube seals (at the
Continental case end, for those like me who thought it was a cylinder
issue).

My mechanic told me that, in his experience, Continental is known for
problems with these seals.

Anyone have any experience with leaking push rod tube seals?

Granted all of this is covered under warranty, but after three and a half
months down, I wanted nothing more than to fly the wings off this aircraft
now that the engine replacement work has completed.