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1. 10:27 AM - Vanishing oil (Bradly Banks)
2. 12:17 PM - Re: Vanishing oil (Monty Barrett Sr)
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Hello All , this topic has probably been thrashed to within an inch of
its
life , but here goes again.
Our =9252 has 1600 hrs TT on the engine and 400 smoh (top set), running
her
up, we get the occasional white puff from the 6,7,8,9 manifold. She is
not
the freshest 52 around but none the less great fun to fly.
The problem starts , when we come in to change passengers or refuel.
After
standing for 5 or six min I have taken to rotating the prop carefully
through 2 rotations before starting again , we get a pint of hot oil
deposited on the ground from no6. After the days flying we run her up
for
30-45 sec ant 60% and shut down for the week. Usually loosing 1-2 litres
for
a 2-3 hours boring holes in the clouds.
On return , the following week , the oil tank has lost 9-10 litres on
the
dip stick. Rotating the prop we get , around =BE of a litre loss at
nearly 10
usd /litre , I need to find the problem .
I have replaced the oil pump with a used serviceable unit , and the
problem
persists.
I have stripped the old oil pump, it is truly a genius piece of thinking
with the scavenger pump and the main oil feed gears being driven off the
same shaft and rotating at different speeds and in opposite directions.
An amo looked at it and pointed me to a relief valve with a hectic
spring
holding it down, im not convinced that this relief valve is the problem
as
the oil is only under the pull of gravity?
I will post pics of the pump in the next post
Any ideas , would be appreciated.
Bradly Banks
Merlin Aviation Services
Cell:0825083200
Tel :0333308580
Email :Brad@runawaymedia.co.za
Skype: bradly.banks
Message 2
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I think you have 2 separate problems. The first is: the bottom rocker
boxes do not scavenge oil. A loose guide on either valve, ( most
llikely the exhaust ),
will allow oil to seep thru the guide into the port and / or the
cylinder. This can happen on any of the lower cylinders. The top
cylinders will also loosen up with time in service but they drain down
the pushrod shroud tube and therefore do not accumulate as much oil.
Secondly: There is a considerable amount of head above the oil pump
check valve; about .6 meters. A leaking check valve will let oil from
the tank into the engine when it is sitting.
It is also a good idea to open the drain cock on the sump at the end of
your flying day and catch the oil in a suitable container to pour back
in the oil tank or discard, your choice. There will be about a liter or
maybe a little more in the sump. The reason for doing this is the sump
is not quite large enough to hold all the oil that will drain from the
engine after it is shut down. It takes a few minutes for all the oil to
drain from the reduction gear, crankcase and accessory section. If the
sump is over full the surplus oil gets above the skirt (s) on the lower
cylinders, runs over into the piston and enters the combustion chamber
by the rings and the oil return holes in the piston.
Your oil consumption agrees with what I have heard reported from other
M14 operators, about a liter in 2 hours. There are ways to reduce this
consumption to a liter in 8-10 hours. Contact me off list and I will
discuss this with you.
Monty Barrett
Barrett Precision Engines, Inc.
Monty@bpaengines.com
-----Original Message-----
From: owner-m14pengines-list-server@matronics.com
[mailto:owner-m14pengines-list-server@matronics.com] On Behalf Of Bradly
Banks
Sent: Wednesday, February 08, 2012 12:19 PM
To: m14pengines-list@matronics.com
Subject: M14PEngines-List: Vanishing oil
Hello All , this topic has probably been thrashed to within an inch of
its life , but here goes again.
Our '52 has 1600 hrs TT on the engine and 400 smoh (top set), running
her up, we get the occasional white puff from the 6,7,8,9 manifold. She
is not the freshest 52 around but none the less great fun to fly.
The problem starts , when we come in to change passengers or refuel.
After standing for 5 or six min I have taken to rotating the prop
carefully through 2 rotations before starting again , we get a pint of
hot oil deposited on the ground from no6. After the days flying we run
her up for 30-45 sec ant 60% and shut down for the week. Usually loosing
1-2 litres for a 2-3 hours boring holes in the clouds.
On return , the following week , the oil tank has lost 9-10 litres on
the dip stick. Rotating the prop we get , around =BE of a litre loss at
nearly 10 usd /litre , I need to find the problem .
I have replaced the oil pump with a used serviceable unit , and the
problem persists.
I have stripped the old oil pump, it is truly a genius piece of
thinking with the scavenger pump and the main oil feed gears being
driven off the same shaft and rotating at different speeds and in
opposite directions.
An amo looked at it and pointed me to a relief valve with a hectic
spring holding it down, im not convinced that this relief valve is the
problem as the oil is only under the pull of gravity?
I will post pics of the pump in the next post
Any ideas , would be appreciated.
Bradly Banks
Merlin Aviation Services
Cell:0825083200
Tel :0333308580
Email :Brad@runawaymedia.co.za
Skype: bradly.banks
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