Mystery Oil leak... cont'd and long

[Jim Burns]

Why would a cold engine drip oil out of the breather? If you're bored or
have any answers... read on.

Lycoming IO-540 C4B5

Like some of the other owners in the group, we've had a mystery oil leak on
one of our engines. Nothing severe, not enough to show up as "missing" on
the dip stick. Primarily just a nuisance.

Last week ours took on a new characteristic that I can't figure out, so I'll
throw a few details at the group to see what tid bits of knowledge,
experience, and plain ole guessing can be generated.

Original leak seemed to be coming from around an oil return hose on our #3
cylinder. Nearly impossible to get my hands on with the bottom cowl in
place, I tightened it up as much as I could without replacing the hose
clamp. Occasionally notice a drop of oil hanging from the bottom of the
inboard end of the hose.

Oil accumulates along the back side of the fuel injector throttle body in a
valley where the throttle body moves upward to connect to the air intake
scat tube.

Small amounts of oil are obviously flying around inside the cowl as single
drops can be found on the bottom of collection points such as bolt heads and
flanges. The floor of the bottom cowl never has any streaks, streams, or
oil lines but is generally covered with a very thin coat of oil that returns
even after washing and wiping it down.

The above observations were constant all summer when using Aeroshell W100.
Never displacing an amount that was observable as a loss on the dipstick.
Normally both engines use about a quart of oil every 6-8 hours if we fill
them up to 12 quarts. If we leave them down around 10 quarts, they can go
up 10 hours before needing to add a quart.

Ok, new observations and clues.
As winter approached we changed oil and filters and switched from W100 to
15W-50. We've flown about 10 hours on this oil change so far, but this is
what I've noticed.

A puddle of oil, I'd say about 2 tablespoons full, appeared on the floor
directly under the breather tube the day AFTER as short 30 minute flight.
The plane came out of a heated hanger and was completely warm and toasty, I
flew it home, tucked it away, no drips or drops as I left our old unheated
hanger. The NEXT evening I went up to the hanger and the puddle was
discovered. I wiped it up, opened the cowls, looked around and everything
seemed as described above (a few drops hanging here and there, oil along the
backside of the throttle body ect.)

The following night, I needed to shovel the snow away from the hanger door,
so I went in and there it was AGAIN! The plane hadn't moved, hadn't flown,
engines not started, but it dripped another 2 tablespoons full of oil out of
the breather tube and onto the floor.

The oil I wiped up off the floor is usually darker colored than the oil on
the dipstick.

So here's what's got me puzzled.... why would a cold engine drip oil out of
the breather? Especially the day AFTER it was flown? I can understand if
there was pressure remaining in the sump there may be some spit out the
breather, but after 24 hours, I can't believe there would be any pressure in
the sump.

Second thought, which I've been told Lycoming's don't have a problem with,
would be a leaking intake valve guide. Could that be seeping oil back down
through the intake and somehow make it to the throttle body? One of the
breather lines goes to the back side of the throttle body and then (I
assume, can't see it) enters the sump. The other breather line goes up
towards the back of the accessory case, towards the oil pump I believe, I
need to investigate this line more, I couldn't see very well.

Any ideas?

Thanks!
Jim

[Mike Rapoport]

Is is possible that it just takes a lot longer for the oil to exit the
breather tube in cold weather because it is thicker due to the lower
temperatures?

Mike
MU-2


"Jim Burns" > wrote in message
...
> Why would a cold engine drip oil out of the breather? If you're bored or
> have any answers... read on.
>
> Lycoming IO-540 C4B5
>
> Like some of the other owners in the group, we've had a mystery oil leak
> on
> one of our engines. Nothing severe, not enough to show up as "missing" on
> the dip stick. Primarily just a nuisance.
>
> Last week ours took on a new characteristic that I can't figure out, so
> I'll
> throw a few details at the group to see what tid bits of knowledge,
> experience, and plain ole guessing can be generated.
>
> Original leak seemed to be coming from around an oil return hose on our #3
> cylinder. Nearly impossible to get my hands on with the bottom cowl in
> place, I tightened it up as much as I could without replacing the hose
> clamp. Occasionally notice a drop of oil hanging from the bottom of the
> inboard end of the hose.
>
> Oil accumulates along the back side of the fuel injector throttle body in
> a
> valley where the throttle body moves upward to connect to the air intake
> scat tube.
>
> Small amounts of oil are obviously flying around inside the cowl as single
> drops can be found on the bottom of collection points such as bolt heads
> and
> flanges. The floor of the bottom cowl never has any streaks, streams, or
> oil lines but is generally covered with a very thin coat of oil that
> returns
> even after washing and wiping it down.
>
> The above observations were constant all summer when using Aeroshell W100.
> Never displacing an amount that was observable as a loss on the dipstick.
> Normally both engines use about a quart of oil every 6-8 hours if we fill
> them up to 12 quarts. If we leave them down around 10 quarts, they can go
> up 10 hours before needing to add a quart.
>
> Ok, new observations and clues.
> As winter approached we changed oil and filters and switched from W100 to
> 15W-50. We've flown about 10 hours on this oil change so far, but this is
> what I've noticed.
>
> A puddle of oil, I'd say about 2 tablespoons full, appeared on the floor
> directly under the breather tube the day AFTER as short 30 minute flight.
> The plane came out of a heated hanger and was completely warm and toasty,
> I
> flew it home, tucked it away, no drips or drops as I left our old unheated
> hanger. The NEXT evening I went up to the hanger and the puddle was
> discovered. I wiped it up, opened the cowls, looked around and everything
> seemed as described above (a few drops hanging here and there, oil along
> the
> backside of the throttle body ect.)
>
> The following night, I needed to shovel the snow away from the hanger
> door,
> so I went in and there it was AGAIN! The plane hadn't moved, hadn't
> flown,
> engines not started, but it dripped another 2 tablespoons full of oil out
> of
> the breather tube and onto the floor.
>
> The oil I wiped up off the floor is usually darker colored than the oil on
> the dipstick.
>
> So here's what's got me puzzled.... why would a cold engine drip oil out
> of
> the breather? Especially the day AFTER it was flown? I can understand if
> there was pressure remaining in the sump there may be some spit out the
> breather, but after 24 hours, I can't believe there would be any pressure
> in
> the sump.
>
> Second thought, which I've been told Lycoming's don't have a problem with,
> would be a leaking intake valve guide. Could that be seeping oil back
> down
> through the intake and somehow make it to the throttle body? One of the
> breather lines goes to the back side of the throttle body and then (I
> assume, can't see it) enters the sump. The other breather line goes up
> towards the back of the accessory case, towards the oil pump I believe, I
> need to investigate this line more, I couldn't see very well.
>
> Any ideas?
>
> Thanks!
> Jim
>
>

[Jim Burns]

Very possible, but why would one engine do it and not the other?

Jim

"Mike Rapoport" > wrote in message
k.net...
> Is is possible that it just takes a lot longer for the oil to exit the
> breather tube in cold weather because it is thicker due to the lower
> temperatures?
>
> Mike
> MU-2
>
>
> "Jim Burns" > wrote in message
> ...
> > Why would a cold engine drip oil out of the breather? If you're bored
or
> > have any answers... read on.
> >
> > Lycoming IO-540 C4B5
> >
> > Like some of the other owners in the group, we've had a mystery oil leak
> > on
> > one of our engines. Nothing severe, not enough to show up as "missing"
on
> > the dip stick. Primarily just a nuisance.
> >
> > Last week ours took on a new characteristic that I can't figure out, so
> > I'll
> > throw a few details at the group to see what tid bits of knowledge,
> > experience, and plain ole guessing can be generated.
> >
> > Original leak seemed to be coming from around an oil return hose on our
#3
> > cylinder. Nearly impossible to get my hands on with the bottom cowl in
> > place, I tightened it up as much as I could without replacing the hose
> > clamp. Occasionally notice a drop of oil hanging from the bottom of the
> > inboard end of the hose.
> >
> > Oil accumulates along the back side of the fuel injector throttle body
in
> > a
> > valley where the throttle body moves upward to connect to the air intake
> > scat tube.
> >
> > Small amounts of oil are obviously flying around inside the cowl as
single
> > drops can be found on the bottom of collection points such as bolt heads
> > and
> > flanges. The floor of the bottom cowl never has any streaks, streams,
or
> > oil lines but is generally covered with a very thin coat of oil that
> > returns
> > even after washing and wiping it down.
> >
> > The above observations were constant all summer when using Aeroshell
W100.
> > Never displacing an amount that was observable as a loss on the
dipstick.
> > Normally both engines use about a quart of oil every 6-8 hours if we
fill
> > them up to 12 quarts. If we leave them down around 10 quarts, they can
go
> > up 10 hours before needing to add a quart.
> >
> > Ok, new observations and clues.
> > As winter approached we changed oil and filters and switched from W100
to
> > 15W-50. We've flown about 10 hours on this oil change so far, but this
is
> > what I've noticed.
> >
> > A puddle of oil, I'd say about 2 tablespoons full, appeared on the floor
> > directly under the breather tube the day AFTER as short 30 minute
flight.
> > The plane came out of a heated hanger and was completely warm and
toasty,
> > I
> > flew it home, tucked it away, no drips or drops as I left our old
unheated
> > hanger. The NEXT evening I went up to the hanger and the puddle was
> > discovered. I wiped it up, opened the cowls, looked around and
everything
> > seemed as described above (a few drops hanging here and there, oil along
> > the
> > backside of the throttle body ect.)
> >
> > The following night, I needed to shovel the snow away from the hanger
> > door,
> > so I went in and there it was AGAIN! The plane hadn't moved, hadn't
> > flown,
> > engines not started, but it dripped another 2 tablespoons full of oil
out
> > of
> > the breather tube and onto the floor.
> >
> > The oil I wiped up off the floor is usually darker colored than the oil
on
> > the dipstick.
> >
> > So here's what's got me puzzled.... why would a cold engine drip oil out
> > of
> > the breather? Especially the day AFTER it was flown? I can understand
if
> > there was pressure remaining in the sump there may be some spit out the
> > breather, but after 24 hours, I can't believe there would be any
pressure
> > in
> > the sump.
> >
> > Second thought, which I've been told Lycoming's don't have a problem
with,
> > would be a leaking intake valve guide. Could that be seeping oil back
> > down
> > through the intake and somehow make it to the throttle body? One of the
> > breather lines goes to the back side of the throttle body and then (I
> > assume, can't see it) enters the sump. The other breather line goes up
> > towards the back of the accessory case, towards the oil pump I believe,
I
> > need to investigate this line more, I couldn't see very well.
> >
> > Any ideas?
> >
> > Thanks!
> > Jim
> >
> >
>
>

[Mike Rapoport]

Perhaps the other engine doesn't send as much oil out the breather, or
perhaps it is out of oil. No idea really, it was just a thought. Try
switching the engines side to side.

Mike
MU-2



"Jim Burns" > wrote in message
...
> Very possible, but why would one engine do it and not the other?
>
> Jim
>
> "Mike Rapoport" > wrote in message
> k.net...
>> Is is possible that it just takes a lot longer for the oil to exit the
>> breather tube in cold weather because it is thicker due to the lower
>> temperatures?
>>
>> Mike
>> MU-2
>>
>>
>> "Jim Burns" > wrote in message
>> ...
>> > Why would a cold engine drip oil out of the breather? If you're bored
> or
>> > have any answers... read on.
>> >
>> > Lycoming IO-540 C4B5
>> >
>> > Like some of the other owners in the group, we've had a mystery oil
>> > leak
>> > on
>> > one of our engines. Nothing severe, not enough to show up as "missing"
> on
>> > the dip stick. Primarily just a nuisance.
>> >
>> > Last week ours took on a new characteristic that I can't figure out, so
>> > I'll
>> > throw a few details at the group to see what tid bits of knowledge,
>> > experience, and plain ole guessing can be generated.
>> >
>> > Original leak seemed to be coming from around an oil return hose on our
> #3
>> > cylinder. Nearly impossible to get my hands on with the bottom cowl in
>> > place, I tightened it up as much as I could without replacing the hose
>> > clamp. Occasionally notice a drop of oil hanging from the bottom of
>> > the
>> > inboard end of the hose.
>> >
>> > Oil accumulates along the back side of the fuel injector throttle body
> in
>> > a
>> > valley where the throttle body moves upward to connect to the air
>> > intake
>> > scat tube.
>> >
>> > Small amounts of oil are obviously flying around inside the cowl as
> single
>> > drops can be found on the bottom of collection points such as bolt
>> > heads
>> > and
>> > flanges. The floor of the bottom cowl never has any streaks, streams,
> or
>> > oil lines but is generally covered with a very thin coat of oil that
>> > returns
>> > even after washing and wiping it down.
>> >
>> > The above observations were constant all summer when using Aeroshell
> W100.
>> > Never displacing an amount that was observable as a loss on the
> dipstick.
>> > Normally both engines use about a quart of oil every 6-8 hours if we
> fill
>> > them up to 12 quarts. If we leave them down around 10 quarts, they can
> go
>> > up 10 hours before needing to add a quart.
>> >
>> > Ok, new observations and clues.
>> > As winter approached we changed oil and filters and switched from W100
> to
>> > 15W-50. We've flown about 10 hours on this oil change so far, but this
> is
>> > what I've noticed.
>> >
>> > A puddle of oil, I'd say about 2 tablespoons full, appeared on the
>> > floor
>> > directly under the breather tube the day AFTER as short 30 minute
> flight.
>> > The plane came out of a heated hanger and was completely warm and
> toasty,
>> > I
>> > flew it home, tucked it away, no drips or drops as I left our old
> unheated
>> > hanger. The NEXT evening I went up to the hanger and the puddle was
>> > discovered. I wiped it up, opened the cowls, looked around and
> everything
>> > seemed as described above (a few drops hanging here and there, oil
>> > along
>> > the
>> > backside of the throttle body ect.)
>> >
>> > The following night, I needed to shovel the snow away from the hanger
>> > door,
>> > so I went in and there it was AGAIN! The plane hadn't moved, hadn't
>> > flown,
>> > engines not started, but it dripped another 2 tablespoons full of oil
> out
>> > of
>> > the breather tube and onto the floor.
>> >
>> > The oil I wiped up off the floor is usually darker colored than the oil
> on
>> > the dipstick.
>> >
>> > So here's what's got me puzzled.... why would a cold engine drip oil
>> > out
>> > of
>> > the breather? Especially the day AFTER it was flown? I can understand
> if
>> > there was pressure remaining in the sump there may be some spit out the
>> > breather, but after 24 hours, I can't believe there would be any
> pressure
>> > in
>> > the sump.
>> >
>> > Second thought, which I've been told Lycoming's don't have a problem
> with,
>> > would be a leaking intake valve guide. Could that be seeping oil back
>> > down
>> > through the intake and somehow make it to the throttle body? One of
>> > the
>> > breather lines goes to the back side of the throttle body and then (I
>> > assume, can't see it) enters the sump. The other breather line goes up
>> > towards the back of the accessory case, towards the oil pump I believe,
> I
>> > need to investigate this line more, I couldn't see very well.
>> >
>> > Any ideas?
>> >
>> > Thanks!
>> > Jim
>> >
>> >
>>
>>
>
>

[Jim Burns]

I think your first idea may be a posibility. leaky engine is 1800 hours
with 600 hour cylinders, dry engine is 600 hours.

The breather lines are small diameter, say 1/4", so I guess cold thick oil
would have a hard time flowing through them and may take several hours.

Jim

"Mike Rapoport" > wrote in message
ink.net...
> Perhaps the other engine doesn't send as much oil out the breather, or
> perhaps it is out of oil. No idea really, it was just a thought. Try
> switching the engines side to side.
>
> Mike
> MU-2
>
>
>
> "Jim Burns" > wrote in message
> ...
> > Very possible, but why would one engine do it and not the other?
> >
> > Jim
> >
> > "Mike Rapoport" > wrote in message
> > k.net...
> >> Is is possible that it just takes a lot longer for the oil to exit the
> >> breather tube in cold weather because it is thicker due to the lower
> >> temperatures?
> >>
> >> Mike
> >> MU-2
> >>
> >>
> >> "Jim Burns" > wrote in message
> >> ...
> >> > Why would a cold engine drip oil out of the breather? If you're
bored
> > or
> >> > have any answers... read on.
> >> >
> >> > Lycoming IO-540 C4B5
> >> >
> >> > Like some of the other owners in the group, we've had a mystery oil
> >> > leak
> >> > on
> >> > one of our engines. Nothing severe, not enough to show up as
"missing"
> > on
> >> > the dip stick. Primarily just a nuisance.
> >> >
> >> > Last week ours took on a new characteristic that I can't figure out,
so
> >> > I'll
> >> > throw a few details at the group to see what tid bits of knowledge,
> >> > experience, and plain ole guessing can be generated.
> >> >
> >> > Original leak seemed to be coming from around an oil return hose on
our
> > #3
> >> > cylinder. Nearly impossible to get my hands on with the bottom cowl
in
> >> > place, I tightened it up as much as I could without replacing the
hose
> >> > clamp. Occasionally notice a drop of oil hanging from the bottom of
> >> > the
> >> > inboard end of the hose.
> >> >
> >> > Oil accumulates along the back side of the fuel injector throttle
body
> > in
> >> > a
> >> > valley where the throttle body moves upward to connect to the air
> >> > intake
> >> > scat tube.
> >> >
> >> > Small amounts of oil are obviously flying around inside the cowl as
> > single
> >> > drops can be found on the bottom of collection points such as bolt
> >> > heads
> >> > and
> >> > flanges. The floor of the bottom cowl never has any streaks,
streams,
> > or
> >> > oil lines but is generally covered with a very thin coat of oil that
> >> > returns
> >> > even after washing and wiping it down.
> >> >
> >> > The above observations were constant all summer when using Aeroshell
> > W100.
> >> > Never displacing an amount that was observable as a loss on the
> > dipstick.
> >> > Normally both engines use about a quart of oil every 6-8 hours if we
> > fill
> >> > them up to 12 quarts. If we leave them down around 10 quarts, they
can
> > go
> >> > up 10 hours before needing to add a quart.
> >> >
> >> > Ok, new observations and clues.
> >> > As winter approached we changed oil and filters and switched from
W100
> > to
> >> > 15W-50. We've flown about 10 hours on this oil change so far, but
this
> > is
> >> > what I've noticed.
> >> >
> >> > A puddle of oil, I'd say about 2 tablespoons full, appeared on the
> >> > floor
> >> > directly under the breather tube the day AFTER as short 30 minute
> > flight.
> >> > The plane came out of a heated hanger and was completely warm and
> > toasty,
> >> > I
> >> > flew it home, tucked it away, no drips or drops as I left our old
> > unheated
> >> > hanger. The NEXT evening I went up to the hanger and the puddle was
> >> > discovered. I wiped it up, opened the cowls, looked around and
> > everything
> >> > seemed as described above (a few drops hanging here and there, oil
> >> > along
> >> > the
> >> > backside of the throttle body ect.)
> >> >
> >> > The following night, I needed to shovel the snow away from the hanger
> >> > door,
> >> > so I went in and there it was AGAIN! The plane hadn't moved, hadn't
> >> > flown,
> >> > engines not started, but it dripped another 2 tablespoons full of oil
> > out
> >> > of
> >> > the breather tube and onto the floor.
> >> >
> >> > The oil I wiped up off the floor is usually darker colored than the
oil
> > on
> >> > the dipstick.
> >> >
> >> > So here's what's got me puzzled.... why would a cold engine drip oil
> >> > out
> >> > of
> >> > the breather? Especially the day AFTER it was flown? I can
understand
> > if
> >> > there was pressure remaining in the sump there may be some spit out
the
> >> > breather, but after 24 hours, I can't believe there would be any
> > pressure
> >> > in
> >> > the sump.
> >> >
> >> > Second thought, which I've been told Lycoming's don't have a problem
> > with,
> >> > would be a leaking intake valve guide. Could that be seeping oil
back
> >> > down
> >> > through the intake and somehow make it to the throttle body? One of
> >> > the
> >> > breather lines goes to the back side of the throttle body and then (I
> >> > assume, can't see it) enters the sump. The other breather line goes
up
> >> > towards the back of the accessory case, towards the oil pump I
believe,
> > I
> >> > need to investigate this line more, I couldn't see very well.
> >> >
> >> > Any ideas?
> >> >
> >> > Thanks!
> >> > Jim
> >> >
> >> >
> >>
> >>
> >
> >
>
>

[Rip]

Jim Burns wrote:

> I think your first idea may be a posibility. leaky engine is 1800 hours
> with 600 hour cylinders, dry engine is 600 hours.
>
> The breather lines are small diameter, say 1/4", so I guess cold thick oil
> would have a hard time flowing through them and may take several hours.
>
> Jim
>
> "Mike Rapoport" > wrote in message
> ink.net...
>
>>Perhaps the other engine doesn't send as much oil out the breather, or
>>perhaps it is out of oil. No idea really, it was just a thought. Try
>>switching the engines side to side.
>>
>>Mike
>>MU-2
>>
>>
>>
>>"Jim Burns" > wrote in message
...
>>
>>>Very possible, but why would one engine do it and not the other?
>>>
>>>Jim
>>>
>>>"Mike Rapoport" > wrote in message
k.net...
>>>
>>>>Is is possible that it just takes a lot longer for the oil to exit the
>>>>breather tube in cold weather because it is thicker due to the lower
>>>>temperatures?
>>>>
>>>>Mike
>>>>MU-2
>>>>
>>>>
>>>>"Jim Burns" > wrote in message
...
>>>>
>>>>>Why would a cold engine drip oil out of the breather? If you're
>
> bored
>
>>>or
>>>
>>>>>have any answers... read on.
>>>>>
>>>>>Lycoming IO-540 C4B5
>>>>>
>>>>>Like some of the other owners in the group, we've had a mystery oil
>>>>>leak
>>>>>on
>>>>>one of our engines. Nothing severe, not enough to show up as
>
> "missing"
>
>>>on
>>>
>>>>>the dip stick. Primarily just a nuisance.
>>>>>
>>>>>Last week ours took on a new characteristic that I can't figure out,
>
> so
>
>>>>>I'll
>>>>>throw a few details at the group to see what tid bits of knowledge,
>>>>>experience, and plain ole guessing can be generated.
>>>>>
>>>>>Original leak seemed to be coming from around an oil return hose on
>
> our
>
>>>#3
>>>
>>>>>cylinder. Nearly impossible to get my hands on with the bottom cowl
>
> in
>
>>>>>place, I tightened it up as much as I could without replacing the
>
> hose
>
>>>>>clamp. Occasionally notice a drop of oil hanging from the bottom of
>>>>>the
>>>>>inboard end of the hose.
>>>>>
>>>>>Oil accumulates along the back side of the fuel injector throttle
>
> body
>
>>>in
>>>
>>>>>a
>>>>>valley where the throttle body moves upward to connect to the air
>>>>>intake
>>>>>scat tube.
>>>>>
>>>>>Small amounts of oil are obviously flying around inside the cowl as
>>>
>>>single
>>>
>>>>>drops can be found on the bottom of collection points such as bolt
>>>>>heads
>>>>>and
>>>>>flanges. The floor of the bottom cowl never has any streaks,
>
> streams,
>
>>>or
>>>
>>>>>oil lines but is generally covered with a very thin coat of oil that
>>>>>returns
>>>>>even after washing and wiping it down.
>>>>>
>>>>>The above observations were constant all summer when using Aeroshell
>>>
>>>W100.
>>>
>>>>>Never displacing an amount that was observable as a loss on the
>>>
>>>dipstick.
>>>
>>>>>Normally both engines use about a quart of oil every 6-8 hours if we
>>>
>>>fill
>>>
>>>>>them up to 12 quarts. If we leave them down around 10 quarts, they
>
> can
>
>>>go
>>>
>>>>>up 10 hours before needing to add a quart.
>>>>>
>>>>>Ok, new observations and clues.
>>>>>As winter approached we changed oil and filters and switched from
>
> W100
>
>>>to
>>>
>>>>>15W-50. We've flown about 10 hours on this oil change so far, but
>
> this
>
>>>is
>>>
>>>>>what I've noticed.
>>>>>
>>>>>A puddle of oil, I'd say about 2 tablespoons full, appeared on the
>>>>>floor
>>>>>directly under the breather tube the day AFTER as short 30 minute
>>>
>>>flight.
>>>
>>>>>The plane came out of a heated hanger and was completely warm and
>>>
>>>toasty,
>>>
>>>>>I
>>>>>flew it home, tucked it away, no drips or drops as I left our old
>>>
>>>unheated
>>>
>>>>>hanger. The NEXT evening I went up to the hanger and the puddle was
>>>>>discovered. I wiped it up, opened the cowls, looked around and
>>>
>>>everything
>>>
>>>>>seemed as described above (a few drops hanging here and there, oil
>>>>>along
>>>>>the
>>>>>backside of the throttle body ect.)
>>>>>
>>>>>The following night, I needed to shovel the snow away from the hanger
>>>>>door,
>>>>>so I went in and there it was AGAIN! The plane hadn't moved, hadn't
>>>>>flown,
>>>>>engines not started, but it dripped another 2 tablespoons full of oil
>>>
>>>out
>>>
>>>>>of
>>>>>the breather tube and onto the floor.
>>>>>
>>>>>The oil I wiped up off the floor is usually darker colored than the
>
> oil
>
>>>on
>>>
>>>>>the dipstick.
>>>>>
>>>>>So here's what's got me puzzled.... why would a cold engine drip oil
>>>>>out
>>>>>of
>>>>>the breather? Especially the day AFTER it was flown? I can
>
> understand
>
>>>if
>>>
>>>>>there was pressure remaining in the sump there may be some spit out
>
> the
>
>>>>>breather, but after 24 hours, I can't believe there would be any
>>>
>>>pressure
>>>
>>>>>in
>>>>>the sump.
>>>>>
>>>>>Second thought, which I've been told Lycoming's don't have a problem
>>>
>>>with,
>>>
>>>>>would be a leaking intake valve guide. Could that be seeping oil
>
> back
>
>>>>>down
>>>>>through the intake and somehow make it to the throttle body? One of
>>>>>the
>>>>>breather lines goes to the back side of the throttle body and then (I
>>>>>assume, can't see it) enters the sump. The other breather line goes
>
> up
>
>>>>>towards the back of the accessory case, towards the oil pump I
>
> believe,
>
>>>I
>>>
>>>>>need to investigate this line more, I couldn't see very well.
>>>>>
>>>>>Any ideas?
>>>>>
>>>>>Thanks!
>>>>>Jim
>>>>>
>>>>>
>>>>
>>>>
>>>
>>
>
>
1/4" is a mighty small breather hose! Check to make sure it's correct!
Also, you might want to make sure the breather line is placed so that it
definitely and distinctly drains back towards the engine, with no low
spots to pool or collect oil in. If you get an oil "pocket" small
changes in temperature can cause the air in the crankcase to "puff" the
oil out of the low spot onto the floor, or wherever.

Rip

[Jim Burns]

AH!! you are sooo correct! The 1/4" hose that is dripping the oil is the
air box drain hose, which exits just ahead of the breather hose (much
larger). Sooo now the mystery gets mysterious! Oil on top of the air box
collects from "where ever" several hours after a flight, seeps into the
airbox then slowly drains out the drain hose???

OR intake valve guide leaking down through the intake tube into the
airbox???

OR...????

Jim

"Rip" > wrote in message
t...
> 1/4" is a mighty small breather hose! Check to make sure it's correct!
> Also, you might want to make sure the breather line is placed so that it
> definitely and distinctly drains back towards the engine, with no low
> spots to pool or collect oil in. If you get an oil "pocket" small
> changes in temperature can cause the air in the crankcase to "puff" the
> oil out of the low spot onto the floor, or wherever.
>
> Rip

[Jay Honeck]

> OR intake valve guide leaking down through the intake tube into the
> airbox???
>
> OR...????

This is why a wise old grey-beard at the airport, upon hearing me bemoaning
the fact that I've got an oil drip AFTER installing an air/oil separator,
remarked: "There are over 100 places that can leak oil on an aircraft
engine. Your air/oil separator has addressed one of them -- and created
three more potential leaks..."

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

[nobody]

Hi Jim,

I wondered if you ever found the source of the oil leak / drip
problem you were chasing?

The idea that this make be a drip out of the air box after oil
has seeped down from the top of the air box sounds reasonable.

Both engines on my Aztec leak and drip. If I ever went into
the hangar and did not find some oil under the engines, I'd
think someone had washed the floor within the last 30 minutes!

Seriously, we'd have lots of leaks on the oil return lines. The
little rubber hoses and associated hose clamps were a nightmare
to get leak-proof.

I was curious about your oil consumption. You stated you could
go 10 hours if filled to the 10 quart level. Our will not do that. At
10 quarts, each engine will be a quart low after a couple of hours.
At the 9 quart level, they will run for 4 to 5 hours before being a quart
low. I'm nervious about letting them get before 8 quarts, but I'm
wondering if they would run at the 8 quart level for a much longer
period of time. My Cessna 172 with its O320 sits happily for hours
on end at the 6 quarts level, while filling it up to its 8 quart capacity
results in losing 2 quarts in a few hours. Scaling this to the IO-540
with the 12 quart sump equates to 9 quarts being the 75% full point,
and I'd think that the level would be stable. But I don't see that on my
IO-540s.

Both engines are high time, but one has less than a 100 hours on all new
cylinders, yet both behave the same. This makes me think that the oil
loss is in the crankcase and is not being burned. Sounds like yours are
stable at 10 quarts. I guess we've more or better leaks than you. Let me
know if you need some :-)

Ronnie


"Jim Burns" > wrote in message
...
> Why would a cold engine drip oil out of the breather? If you're bored or
> have any answers... read on.
>
> Lycoming IO-540 C4B5
>
> Like some of the other owners in the group, we've had a mystery oil leak
> on
> one of our engines. Nothing severe, not enough to show up as "missing" on
> the dip stick. Primarily just a nuisance.
>
> Last week ours took on a new characteristic that I can't figure out, so
> I'll
> throw a few details at the group to see what tid bits of knowledge,
> experience, and plain ole guessing can be generated.
>
> Original leak seemed to be coming from around an oil return hose on our #3
> cylinder. Nearly impossible to get my hands on with the bottom cowl in
> place, I tightened it up as much as I could without replacing the hose
> clamp. Occasionally notice a drop of oil hanging from the bottom of the
> inboard end of the hose.
>
> Oil accumulates along the back side of the fuel injector throttle body in
> a
> valley where the throttle body moves upward to connect to the air intake
> scat tube.
>
> Small amounts of oil are obviously flying around inside the cowl as single
> drops can be found on the bottom of collection points such as bolt heads
> and
> flanges. The floor of the bottom cowl never has any streaks, streams, or
> oil lines but is generally covered with a very thin coat of oil that
> returns
> even after washing and wiping it down.
>
> The above observations were constant all summer when using Aeroshell W100.
> Never displacing an amount that was observable as a loss on the dipstick.
> Normally both engines use about a quart of oil every 6-8 hours if we fill
> them up to 12 quarts. If we leave them down around 10 quarts, they can go
> up 10 hours before needing to add a quart.
>
> Ok, new observations and clues.
> As winter approached we changed oil and filters and switched from W100 to
> 15W-50. We've flown about 10 hours on this oil change so far, but this is
> what I've noticed.
>
> A puddle of oil, I'd say about 2 tablespoons full, appeared on the floor
> directly under the breather tube the day AFTER as short 30 minute flight.
> The plane came out of a heated hanger and was completely warm and toasty,
> I
> flew it home, tucked it away, no drips or drops as I left our old unheated
> hanger. The NEXT evening I went up to the hanger and the puddle was
> discovered. I wiped it up, opened the cowls, looked around and everything
> seemed as described above (a few drops hanging here and there, oil along
> the
> backside of the throttle body ect.)
>
> The following night, I needed to shovel the snow away from the hanger
> door,
> so I went in and there it was AGAIN! The plane hadn't moved, hadn't
> flown,
> engines not started, but it dripped another 2 tablespoons full of oil out
> of
> the breather tube and onto the floor.
>
> The oil I wiped up off the floor is usually darker colored than the oil on
> the dipstick.
>
> So here's what's got me puzzled.... why would a cold engine drip oil out
> of
> the breather? Especially the day AFTER it was flown? I can understand if
> there was pressure remaining in the sump there may be some spit out the
> breather, but after 24 hours, I can't believe there would be any pressure
> in
> the sump.
>
> Second thought, which I've been told Lycoming's don't have a problem with,
> would be a leaking intake valve guide. Could that be seeping oil back
> down
> through the intake and somehow make it to the throttle body? One of the
> breather lines goes to the back side of the throttle body and then (I
> assume, can't see it) enters the sump. The other breather line goes up
> towards the back of the accessory case, towards the oil pump I believe, I
> need to investigate this line more, I couldn't see very well.
>
> Any ideas?
>
> Thanks!
> Jim
>
>

[[email protected]]

When most of these engines were certified, the rule was a gallon of oil
for each 100 hp.
You shouldn't have a problem running down in the 4-6 quart range. It all
depends where the oil pickup is.
Every pickup I've seen would run oil in the 2-3 quart range without
problems.
With this, I'm still most comfortable in the 6-8 quart range. Its nice
to have that buffer zone of excess oil.


nobody wrote:
> Hi Jim,
>
> I wondered if you ever found the source of the oil leak / drip
> problem you were chasing?
>
> The idea that this make be a drip out of the air box after oil
> has seeped down from the top of the air box sounds reasonable.
>
> Both engines on my Aztec leak and drip. If I ever went into
> the hangar and did not find some oil under the engines, I'd
> think someone had washed the floor within the last 30 minutes!
>
> Seriously, we'd have lots of leaks on the oil return lines. The
> little rubber hoses and associated hose clamps were a nightmare
> to get leak-proof.
>
> I was curious about your oil consumption. You stated you could
> go 10 hours if filled to the 10 quart level. Our will not do that. At
> 10 quarts, each engine will be a quart low after a couple of hours.
> At the 9 quart level, they will run for 4 to 5 hours before being a quart
> low. I'm nervious about letting them get before 8 quarts, but I'm
> wondering if they would run at the 8 quart level for a much longer
> period of time. My Cessna 172 with its O320 sits happily for hours
> on end at the 6 quarts level, while filling it up to its 8 quart capacity
> results in losing 2 quarts in a few hours. Scaling this to the IO-540
> with the 12 quart sump equates to 9 quarts being the 75% full point,
> and I'd think that the level would be stable. But I don't see that on my
> IO-540s.
>
> Both engines are high time, but one has less than a 100 hours on all new
> cylinders, yet both behave the same. This makes me think that the oil
> loss is in the crankcase and is not being burned. Sounds like yours are
> stable at 10 quarts. I guess we've more or better leaks than you. Let me
> know if you need some :-)
>
> Ronnie
>
>
> "Jim Burns" > wrote in message
> ...
>
>>Why would a cold engine drip oil out of the breather? If you're bored or
>>have any answers... read on.
>>
>>Lycoming IO-540 C4B5
>>
>>Like some of the other owners in the group, we've had a mystery oil leak
>>on
>>one of our engines. Nothing severe, not enough to show up as "missing" on
>>the dip stick. Primarily just a nuisance.
>>
>>Last week ours took on a new characteristic that I can't figure out, so
>>I'll
>>throw a few details at the group to see what tid bits of knowledge,
>>experience, and plain ole guessing can be generated.
>>
>>Original leak seemed to be coming from around an oil return hose on our #3
>>cylinder. Nearly impossible to get my hands on with the bottom cowl in
>>place, I tightened it up as much as I could without replacing the hose
>>clamp. Occasionally notice a drop of oil hanging from the bottom of the
>>inboard end of the hose.
>>
>>Oil accumulates along the back side of the fuel injector throttle body in
>>a
>>valley where the throttle body moves upward to connect to the air intake
>>scat tube.
>>
>>Small amounts of oil are obviously flying around inside the cowl as single
>>drops can be found on the bottom of collection points such as bolt heads
>>and
>>flanges. The floor of the bottom cowl never has any streaks, streams, or
>>oil lines but is generally covered with a very thin coat of oil that
>>returns
>>even after washing and wiping it down.
>>
>>The above observations were constant all summer when using Aeroshell W100.
>>Never displacing an amount that was observable as a loss on the dipstick.
>>Normally both engines use about a quart of oil every 6-8 hours if we fill
>>them up to 12 quarts. If we leave them down around 10 quarts, they can go
>>up 10 hours before needing to add a quart.
>>
>>Ok, new observations and clues.
>>As winter approached we changed oil and filters and switched from W100 to
>>15W-50. We've flown about 10 hours on this oil change so far, but this is
>>what I've noticed.
>>
>>A puddle of oil, I'd say about 2 tablespoons full, appeared on the floor
>>directly under the breather tube the day AFTER as short 30 minute flight.
>>The plane came out of a heated hanger and was completely warm and toasty,
>>I
>>flew it home, tucked it away, no drips or drops as I left our old unheated
>>hanger. The NEXT evening I went up to the hanger and the puddle was
>>discovered. I wiped it up, opened the cowls, looked around and everything
>>seemed as described above (a few drops hanging here and there, oil along
>>the
>>backside of the throttle body ect.)
>>
>>The following night, I needed to shovel the snow away from the hanger
>>door,
>>so I went in and there it was AGAIN! The plane hadn't moved, hadn't
>>flown,
>>engines not started, but it dripped another 2 tablespoons full of oil out
>>of
>>the breather tube and onto the floor.
>>
>>The oil I wiped up off the floor is usually darker colored than the oil on
>>the dipstick.
>>
>>So here's what's got me puzzled.... why would a cold engine drip oil out
>>of
>>the breather? Especially the day AFTER it was flown? I can understand if
>>there was pressure remaining in the sump there may be some spit out the
>>breather, but after 24 hours, I can't believe there would be any pressure
>>in
>>the sump.
>>
>>Second thought, which I've been told Lycoming's don't have a problem with,
>>would be a leaking intake valve guide. Could that be seeping oil back
>>down
>>through the intake and somehow make it to the throttle body? One of the
>>breather lines goes to the back side of the throttle body and then (I
>>assume, can't see it) enters the sump. The other breather line goes up
>>towards the back of the accessory case, towards the oil pump I believe, I
>>need to investigate this line more, I couldn't see very well.
>>
>>Any ideas?
>>
>>Thanks!
>>Jim
>>
>>
>
>
>

[Jim Burns]

Hi Ronnie,
Between the Wisconsin weather and a funky DG, we haven't been able to fly
enough to figure out if we've solved our leak. We found that the base of
the dipstick/filler tube was loose. We also noticed that there was no oil
staining in front of the tube but plenty on the aft side of the tube. Since
we've tightened that up and re safety wired it, we haven't flown. Next time
the bottom cowls come off, the oil return lines will all get checked and
double checked.

Our experience with IO-540's started with when we leased a 182RG. Although
it had a different model of the IO540, was derated to 235hp, and no doubt
had a different sump, pickup, and breather arrangement, the POH recommended
that the oil be filled to 12 quarts before extended trips but that 8 quarts
was the normal level. Apparently, Cessna wanted you to "top it off" before
a long cross country, let it blow out any excess and you'd have plenty of
oil left for the remainder of the trip.

We've sort of followed the same routine with the Aztec. Most of our trips
are several hours long so when ever we change oil they get filled with 12
quarts + enough to fill the filter. Then we let them blow out the extra
quart or two and they seem to stabilize at 10 quarts after about 5 hours.
( the first quart will blow out after about 2 hours, then the next it takes
at least another 3 hours) Both engines will stay at 10 quarts for another
10 hours. So, infact it actually takes over 15 hours to have them below 10
quarts if filled to 12 beforehand. They really don't seem to burn hardly
any oil. One engine is a 600 hour Penn Yan, and the left is a 1850 hour
Mattituck with 400-500 hour cylinders. Even with the drip on the left
engine, it was never enough to notice on the dipstick, even after 10 hours
at the 10 quart level.

I'll pass on the extra leaks.... we're pretty spoiled. Our right engine
doesn't leak a drop, so when I see a few on the left, I freak! :) Guess I
need some round engine time and maybe I'd get used to it!

Jim



"nobody" > wrote in message
om...
> Hi Jim,
>
> I wondered if you ever found the source of the oil leak / drip
> problem you were chasing?
>
> The idea that this make be a drip out of the air box after oil
> has seeped down from the top of the air box sounds reasonable.
>
> Both engines on my Aztec leak and drip. If I ever went into
> the hangar and did not find some oil under the engines, I'd
> think someone had washed the floor within the last 30 minutes!
>
> Seriously, we'd have lots of leaks on the oil return lines. The
> little rubber hoses and associated hose clamps were a nightmare
> to get leak-proof.
>
> I was curious about your oil consumption. You stated you could
> go 10 hours if filled to the 10 quart level. Our will not do that. At
> 10 quarts, each engine will be a quart low after a couple of hours.
> At the 9 quart level, they will run for 4 to 5 hours before being a quart
> low. I'm nervious about letting them get before 8 quarts, but I'm
> wondering if they would run at the 8 quart level for a much longer
> period of time. My Cessna 172 with its O320 sits happily for hours
> on end at the 6 quarts level, while filling it up to its 8 quart capacity
> results in losing 2 quarts in a few hours. Scaling this to the IO-540
> with the 12 quart sump equates to 9 quarts being the 75% full point,
> and I'd think that the level would be stable. But I don't see that on my
> IO-540s.
>
> Both engines are high time, but one has less than a 100 hours on all new
> cylinders, yet both behave the same. This makes me think that the oil
> loss is in the crankcase and is not being burned. Sounds like yours are
> stable at 10 quarts. I guess we've more or better leaks than you. Let me
> know if you need some :-)
>
> Ronnie
>
>
> "Jim Burns" > wrote in message
> ...
> > Why would a cold engine drip oil out of the breather? If you're bored
or
> > have any answers... read on.
> >
> > Lycoming IO-540 C4B5
> >
> > Like some of the other owners in the group, we've had a mystery oil leak
> > on
> > one of our engines. Nothing severe, not enough to show up as "missing"
on
> > the dip stick. Primarily just a nuisance.
> >
> > Last week ours took on a new characteristic that I can't figure out, so
> > I'll
> > throw a few details at the group to see what tid bits of knowledge,
> > experience, and plain ole guessing can be generated.
> >
> > Original leak seemed to be coming from around an oil return hose on our
#3
> > cylinder. Nearly impossible to get my hands on with the bottom cowl in
> > place, I tightened it up as much as I could without replacing the hose
> > clamp. Occasionally notice a drop of oil hanging from the bottom of the
> > inboard end of the hose.
> >
> > Oil accumulates along the back side of the fuel injector throttle body
in
> > a
> > valley where the throttle body moves upward to connect to the air intake
> > scat tube.
> >
> > Small amounts of oil are obviously flying around inside the cowl as
single
> > drops can be found on the bottom of collection points such as bolt heads
> > and
> > flanges. The floor of the bottom cowl never has any streaks, streams,
or
> > oil lines but is generally covered with a very thin coat of oil that
> > returns
> > even after washing and wiping it down.
> >
> > The above observations were constant all summer when using Aeroshell
W100.
> > Never displacing an amount that was observable as a loss on the
dipstick.
> > Normally both engines use about a quart of oil every 6-8 hours if we
fill
> > them up to 12 quarts. If we leave them down around 10 quarts, they can
go
> > up 10 hours before needing to add a quart.
> >
> > Ok, new observations and clues.
> > As winter approached we changed oil and filters and switched from W100
to
> > 15W-50. We've flown about 10 hours on this oil change so far, but this
is
> > what I've noticed.
> >
> > A puddle of oil, I'd say about 2 tablespoons full, appeared on the floor
> > directly under the breather tube the day AFTER as short 30 minute
flight.
> > The plane came out of a heated hanger and was completely warm and
toasty,
> > I
> > flew it home, tucked it away, no drips or drops as I left our old
unheated
> > hanger. The NEXT evening I went up to the hanger and the puddle was
> > discovered. I wiped it up, opened the cowls, looked around and
everything
> > seemed as described above (a few drops hanging here and there, oil along
> > the
> > backside of the throttle body ect.)
> >
> > The following night, I needed to shovel the snow away from the hanger
> > door,
> > so I went in and there it was AGAIN! The plane hadn't moved, hadn't
> > flown,
> > engines not started, but it dripped another 2 tablespoons full of oil
out
> > of
> > the breather tube and onto the floor.
> >
> > The oil I wiped up off the floor is usually darker colored than the oil
on
> > the dipstick.
> >
> > So here's what's got me puzzled.... why would a cold engine drip oil out
> > of
> > the breather? Especially the day AFTER it was flown? I can understand
if
> > there was pressure remaining in the sump there may be some spit out the
> > breather, but after 24 hours, I can't believe there would be any
pressure
> > in
> > the sump.
> >
> > Second thought, which I've been told Lycoming's don't have a problem
with,
> > would be a leaking intake valve guide. Could that be seeping oil back
> > down
> > through the intake and somehow make it to the throttle body? One of the
> > breather lines goes to the back side of the throttle body and then (I
> > assume, can't see it) enters the sump. The other breather line goes up
> > towards the back of the accessory case, towards the oil pump I believe,
I
> > need to investigate this line more, I couldn't see very well.
> >
> > Any ideas?
> >
> > Thanks!
> > Jim
> >
> >
>
>

[nobody]

Thanks. I may do a little testing at the 6 to 7 quart level
and see how the consumption looks after an hour.

Ronnie

> wrote in message
. ..
> When most of these engines were certified, the rule was a gallon of oil
> for each 100 hp.
> You shouldn't have a problem running down in the 4-6 quart range. It all
> depends where the oil pickup is.
> Every pickup I've seen would run oil in the 2-3 quart range without
> problems.
> With this, I'm still most comfortable in the 6-8 quart range. Its nice to
> have that buffer zone of excess oil.
>
>
> nobody wrote:
>> Hi Jim,
>>
>> I wondered if you ever found the source of the oil leak / drip
>> problem you were chasing?
>>
>> The idea that this make be a drip out of the air box after oil
>> has seeped down from the top of the air box sounds reasonable.
>>
>> Both engines on my Aztec leak and drip. If I ever went into
>> the hangar and did not find some oil under the engines, I'd
>> think someone had washed the floor within the last 30 minutes!
>>
>> Seriously, we'd have lots of leaks on the oil return lines. The
>> little rubber hoses and associated hose clamps were a nightmare
>> to get leak-proof.
>>
>> I was curious about your oil consumption. You stated you could
>> go 10 hours if filled to the 10 quart level. Our will not do that. At
>> 10 quarts, each engine will be a quart low after a couple of hours.
>> At the 9 quart level, they will run for 4 to 5 hours before being a quart
>> low. I'm nervious about letting them get before 8 quarts, but I'm
>> wondering if they would run at the 8 quart level for a much longer
>> period of time. My Cessna 172 with its O320 sits happily for hours
>> on end at the 6 quarts level, while filling it up to its 8 quart capacity
>> results in losing 2 quarts in a few hours. Scaling this to the IO-540
>> with the 12 quart sump equates to 9 quarts being the 75% full point,
>> and I'd think that the level would be stable. But I don't see that on my
>> IO-540s.
>>
>> Both engines are high time, but one has less than a 100 hours on all new
>> cylinders, yet both behave the same. This makes me think that the oil
>> loss is in the crankcase and is not being burned. Sounds like yours are
>> stable at 10 quarts. I guess we've more or better leaks than you. Let
>> me
>> know if you need some :-)
>>
>> Ronnie
>>
>>
>> "Jim Burns" > wrote in message
>> ...
>>
>>>Why would a cold engine drip oil out of the breather? If you're bored or
>>>have any answers... read on.
>>>
>>>Lycoming IO-540 C4B5
>>>
>>>Like some of the other owners in the group, we've had a mystery oil leak
>>>on
>>>one of our engines. Nothing severe, not enough to show up as "missing"
>>>on
>>>the dip stick. Primarily just a nuisance.
>>>
>>>Last week ours took on a new characteristic that I can't figure out, so
>>>I'll
>>>throw a few details at the group to see what tid bits of knowledge,
>>>experience, and plain ole guessing can be generated.
>>>
>>>Original leak seemed to be coming from around an oil return hose on our
>>>#3
>>>cylinder. Nearly impossible to get my hands on with the bottom cowl in
>>>place, I tightened it up as much as I could without replacing the hose
>>>clamp. Occasionally notice a drop of oil hanging from the bottom of the
>>>inboard end of the hose.
>>>
>>>Oil accumulates along the back side of the fuel injector throttle body in
>>>a
>>>valley where the throttle body moves upward to connect to the air intake
>>>scat tube.
>>>
>>>Small amounts of oil are obviously flying around inside the cowl as
>>>single
>>>drops can be found on the bottom of collection points such as bolt heads
>>>and
>>>flanges. The floor of the bottom cowl never has any streaks, streams, or
>>>oil lines but is generally covered with a very thin coat of oil that
>>>returns
>>>even after washing and wiping it down.
>>>
>>>The above observations were constant all summer when using Aeroshell
>>>W100.
>>>Never displacing an amount that was observable as a loss on the dipstick.
>>>Normally both engines use about a quart of oil every 6-8 hours if we fill
>>>them up to 12 quarts. If we leave them down around 10 quarts, they can
>>>go
>>>up 10 hours before needing to add a quart.
>>>
>>>Ok, new observations and clues.
>>>As winter approached we changed oil and filters and switched from W100 to
>>>15W-50. We've flown about 10 hours on this oil change so far, but this
>>>is
>>>what I've noticed.
>>>
>>>A puddle of oil, I'd say about 2 tablespoons full, appeared on the floor
>>>directly under the breather tube the day AFTER as short 30 minute flight.
>>>The plane came out of a heated hanger and was completely warm and toasty,
>>>I
>>>flew it home, tucked it away, no drips or drops as I left our old
>>>unheated
>>>hanger. The NEXT evening I went up to the hanger and the puddle was
>>>discovered. I wiped it up, opened the cowls, looked around and
>>>everything
>>>seemed as described above (a few drops hanging here and there, oil along
>>>the
>>>backside of the throttle body ect.)
>>>
>>>The following night, I needed to shovel the snow away from the hanger
>>>door,
>>>so I went in and there it was AGAIN! The plane hadn't moved, hadn't
>>>flown,
>>>engines not started, but it dripped another 2 tablespoons full of oil out
>>>of
>>>the breather tube and onto the floor.
>>>
>>>The oil I wiped up off the floor is usually darker colored than the oil
>>>on
>>>the dipstick.
>>>
>>>So here's what's got me puzzled.... why would a cold engine drip oil out
>>>of
>>>the breather? Especially the day AFTER it was flown? I can understand
>>>if
>>>there was pressure remaining in the sump there may be some spit out the
>>>breather, but after 24 hours, I can't believe there would be any pressure
>>>in
>>>the sump.
>>>
>>>Second thought, which I've been told Lycoming's don't have a problem
>>>with,
>>>would be a leaking intake valve guide. Could that be seeping oil back
>>>down
>>>through the intake and somehow make it to the throttle body? One of the
>>>breather lines goes to the back side of the throttle body and then (I
>>>assume, can't see it) enters the sump. The other breather line goes up
>>>towards the back of the accessory case, towards the oil pump I believe, I
>>>need to investigate this line more, I couldn't see very well.
>>>
>>>Any ideas?
>>>
>>>Thanks!
>>>Jim
>>>
>>>
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