Today's Message Index:
----------------------
1. 06:03 AM - Re: Lycoming oil flow (Gary Casey)
2. 08:30 AM - Lycoming oil flow (J. Mcculley)
3. 05:40 PM - Re: Re: Lycoming oil flow (Noel Loveys)
Message 1
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| Subject: | Re: Lycoming oil flow |
Appearances can be deceiving. The oil flow order is: Inlet screen,
pump, vernatherm and cooler in parallel, filter, relief valve and
then to the right and left side headers. The feeds for the vacuum
pump, AN fuel pump and hydraulic pump drives are taken off ahead of
the relief valve and all the other functions are taken after the
valve. According to the book this is true of all 4 and 6-cylinder
engines, including, I believe, the aerobatic engines - the internal
oil sump is just replaced by an external oil tank.
Gary Casey
On Jul 5, 2006, at 11:56 PM, Engines-List Digest Server wrote:
> I'm trying to figure out how the oil system in my Lycoming O-540
> works.
> I know there is a great deal of variability between models, but I
> wonder if someone can help me make sense of what I've found. From the
> back of the sump, there is an finger screen in the oil pickup tube and
> from there the oil goes up to the pump. From the pump it goes to two
> possible places, oil cooler or oil filter. Lets assume the oil is
> cold
> and the vernitherm (located next to the oil filter assembly) is open.
> Since it is open, oil flows past the vernitherm and onto the outside
> surface of the filtering element inside of the oil filter. It returns
> down the middle of the filter and goes to the right side oil galley.
> This is the location of the oil pressure valve which regulates
> pressure
> by dumping any excess to the sump. If the oil is getting hot, the
> vernitherm closes and more oil is forced from the pump into the oil
> coolers. The return from the coolers is into the left side oil
> galley.
>
> This is all the information I can deduce from the exterior of the
> accessory case. I'm sure there are more details that I'm missing.
> For
> example, it would seem that only the right galley gets filtered oil
> and
> only the left galley get cool oil. My attempt at describing the
> system
> also seems to imply that oil is either filtered or cooled but not both
> at the same time.
>
> Can somebody please assist me in filling in the missing passages and
> make sense of all this?
>
> Thanks.
> Bernard Despins
Message 2
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| Subject: | Lycoming oil flow |
--> Engines-List message posted by: "J. Mcculley" <mcculleyja@starpower.net>
The path of the oil is correctly described up to the point where you
stated "return from the coolers is into the left side oil galley".
The return from the cooler follows the same path as does the oil when
cold and not passing through the cooler. It goes from the pump to the
outside of the oil filter element either directly from the pump or as
return oil from the cooler to the outside of the filter. The path is
determined by whether the vernatherm valve is on its seat or not. After
the oil passes through the filter it goes directly to the right oil
galley where it passes the pressure sensor port, the oil pressure relief
valve and a crossover channel to the left oil galley.
Actually, while the oil is still cold it can flow in parallel paths
through both the cooler and also the more direct path through the open
vernatherm valve. The path of least resistance is automatically via the
direct route and not the higher resistance path through the cooler. As
the oil heats, the vernatherm slowly closes completely, forcing all the
oil to take the higher resistance path through the cooler. This
modulated flow path thus regulates the temperature during periods when
only partial flow through the cooler is appropriate to maintain desired
temperature.
There is no difference in the oil flow path through the oil galleys and
all the bearings due to the vernatherm. The only difference is
whether the oil is forced to flow partially or completely through the
cooler before continuing through the engine.
The path can best be seen by studying the accessory case when it is not
installed on the engine. External views of the installed case can easily
deceive one!
Jim McCulley
------------------------------------------------------------------------
Time: 07:03:39 AM PST US
--> Engines-List message posted by: Bernard Despins
<bdespins@telusplanet.net>
I'm trying to figure out how the oil system in my Lycoming O-540 works.
I know there is a great deal of variability between models, but I
wonder if someone can help me make sense of what I've found. From the
back of the sump, there is an finger screen in the oil pickup tube and
from there the oil goes up to the pump. From the pump it goes to two
possible places, oil cooler or oil filter. Lets assume the oil is cold
and the vernitherm (located next to the oil filter assembly) is open.
Since it is open, oil flows past the vernitherm and onto the outside
surface of the filtering element inside of the oil filter. It returns
down the middle of the filter and goes to the right side oil galley.
This is the location of the oil pressure valve which regulates pressure
by dumping any excess to the sump. If the oil is getting hot, the
vernitherm closes and more oil is forced from the pump into the oil
coolers. The return from the coolers is into the left side oil galley.
This is all the information I can deduce from the exterior of the
accessory case. I'm sure there are more details that I'm missing. For
example, it would seem that only the right galley gets filtered oil and
only the left galley get cool oil. My attempt at describing the system
also seems to imply that oil is either filtered or cooled but not both
at the same time.
Can somebody please assist me in filling in the missing passages and
make sense of all this?
Thanks.
Bernard Despins
Message 3
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| Subject: | Re: Lycoming oil flow |
I just happened to have a squint at the AVCO Lycoming overhaul manual
today.
One of the things I was looking up was the oil flow diagram. It is
exactly
as you described it including the A engines.
Noel
-----Original Message-----
[mailto:owner-engines-list-server@matronics.com] On Behalf Of Gary Casey
Sent: Thursday, July 06, 2006 10:27 AM
Appearances can be deceiving. The oil flow order is: Inlet screen,
pump,
vernatherm and cooler in parallel, filter, relief valve and then to the
right and left side headers. The feeds for the vacuum pump, AN fuel
pump
and hydraulic pump drives are taken off ahead of the relief valve and
all
the other functions are taken after the valve. According to the book
this
is true of all 4 and 6-cylinder engines, including, I believe, the
aerobatic
engines - the internal oil sump is just replaced by an external oil
tank.
Gary Casey
On Jul 5, 2006, at 11:56 PM, Engines-List Digest Server wrote:
I'm trying to figure out how the oil system in my Lycoming O-540 works.
I know there is a great deal of variability between models, but I
wonder if someone can help me make sense of what I've found. From the
back of the sump, there is an finger screen in the oil pickup tube and
from there the oil goes up to the pump. From the pump it goes to two
possible places, oil cooler or oil filter. Lets assume the oil is cold
and the vernitherm (located next to the oil filter assembly) is open.
Since it is open, oil flows past the vernitherm and onto the outside
surface of the filtering element inside of the oil filter. It returns
down the middle of the filter and goes to the right side oil galley.
This is the location of the oil pressure valve which regulates pressure
by dumping any excess to the sump. If the oil is getting hot, the
vernitherm closes and more oil is forced from the pump into the oil
coolers. The return from the coolers is into the left side oil galley.
This is all the information I can deduce from the exterior of the
accessory case. I'm sure there are more details that I'm missing. For
example, it would seem that only the right galley gets filtered oil and
only the left galley get cool oil. My attempt at describing the system
also seems to imply that oil is either filtered or cooled but not both
at the same time.
Can somebody please assist me in filling in the missing passages and
make sense of all this?
Thanks.
Bernard Despins
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