Shutting down engine Question

Lisa, the reason for a relatively high RPM for a few minutes just before
shutdown is to help prevent lead fouling of the spark plugs. Lycoming engines
tend to run too cold at low RPMs to keep the lead salts from avgas burned off
the plugs.

Best regards,

Steve Robertson
N4732J 1967 Beechcraft Musketeer (Lycoming IO-360)

Roger Long wrote:

1800 is better (with the leaning mentioned above) but you won't make any
friends in the tiedowns using those RPMs. We've found the 1200 to be
sufficient.

--
Roger Long

Dan Luke wrote in message
...

"Lisa" wrote:
The POH says throttle full aft, then mixture cut-off to shut
down.

Which is best?


According to Lycoming Service Letter L192:

"Prior to engine shut-down the engine speed should be maintained between
1000 and 1200 RPM until the operating temperatures have stabilized. At
this time the engine speed should be increased to approximately 1800 RPM
for 15 to 20 seconds, then reduced to 1000 to 1200 RPM and shut-down
immediately using the mixture control."
--
Dan
C172RG at BFM
(remove pants to reply by email)

"Lisa" wrote in message ...
Perhaps this doesn't matter much for a non-turbocharged engine,
but an instructor says that it is best to idle the engine at
1,000 RPM for a few moments before Mixtu Idle Cut-Off at that
RPM to shut down.

The POH says throttle full aft, then mixture cut-off to shut
down.

I run at 1100 RPM just before shutdown, set the throttle
lock, and then pull the mixture back. This way, when I
restart on a cold day, I know that the engine will fire and
idle nicely at 700 RPM without overrevving or conking out.
This minimizes engine wear on startup.

Not sure I agree with posts (from Lycoming recommendation)
which suggest high RPM. Too much risk of damage to the
prop.

On Wed, 31 Mar 2004 06:31:51 -0600, "Dan Luke"
wrote:


"Lisa" wrote:
The POH says throttle full aft, then mixture cut-off to shut
down.

Which is best?


According to Lycoming Service Letter L192:

"Prior to engine shut-down the engine speed should be maintained between
1000 and 1200 RPM until the operating temperatures have stabilized. At
this time the engine speed should be increased to approximately 1800 RPM
for 15 to 20 seconds, then reduced to 1000 to 1200 RPM and shut-down
immediately using the mixture control."

Does the Lycoming service letter explain what running at 1800RPM
accomplishes?

"Nathan Young" wrote:
Does the Lycoming service letter explain what running
at 1800RPM accomplishes?

It is part of a series of recommendations to prevent plug fouling.
--
Dan
C172RG at BFM
(remove pants to reply by email)

"Roger Long" wrote:
1800 is better (with the leaning mentioned above) but you won't
make any friends in the tiedowns using those RPMs.

Yes. The procedure must be used with consideration for others.

Since I started following Lycoming's procedure, I no longer have any
fouling problems.
--
Dan
C172RG at BFM
(remove pants to reply by email)

Yes, you will have more prop wear. However, if you have an O-320 H2AD, the
most vulnerable thing in the engine are the camshaft and lifters. Idling
below 1000 is hard on them because of reduced oil splash and higher metal
pressures. Better a $500 prop overhaul than the $8000 camshaft replacement
we just went through.

--
Roger Long

Tony Cox wrote in message
ink.net...
"Lisa" wrote in message
...
Perhaps this doesn't matter much for a non-turbocharged engine,
but an instructor says that it is best to idle the engine at
1,000 RPM for a few moments before Mixtu Idle Cut-Off at that
RPM to shut down.

The POH says throttle full aft, then mixture cut-off to shut
down.

I run at 1100 RPM just before shutdown, set the throttle
lock, and then pull the mixture back. This way, when I
restart on a cold day, I know that the engine will fire and
idle nicely at 700 RPM without overrevving or conking out.
This minimizes engine wear on startup.

Not sure I agree with posts (from Lycoming recommendation)
which suggest high RPM. Too much risk of damage to the
prop.

"Hilton" wrote in message
ink.net...
[...]
So the CFI wanted Lisa to shutdown "...at that RPM" and this does not
"...clearly imply to reduce RPM".

It does to me. "A few moments before" could even be reasonably interpreted
as "run the engine at 1000 RPM for any period of time, but make sure there
are a few moments between reducing engine speed and shutdown".

Hope that clarifies it.

I think you're pretty foolish to think that the original instruction was not
ambiguous. The fact that we're even having this discussion proves that it
is.

Pete

Don Tuite wrote in message . ..

On hot days, the O-300 in the 'Hawk tends to diesel on after you pull
the mixture. Opening the throttle a little makes it stop.

Don,

Sounds like you have a fuel leak into the manifold. Pulling the
mixture to cutoff should, well, cut off the fuel flow. This could be
something in your carb, or might be a leak in your primer system.
Either way, it shouldn't continue to run after you've cut off the fuel
supply. That's an indication of a problem in the fuel system.

John Galban=====N4BQ (PA28-180)

On Wed, 31 Mar 2004 10:25:02 GMT, "Roger Long"
om wrote:

This is the procedure we use on our O-320 and have had noticeably smoother
and quicker starts since we started it:

RPM - 1200
Lean for maximum RPM rise. (Don't worry, no amount of leaning will hurt the
engine at this low power)
Run 20 seconds
Throttle - Quickly to Idle
Mixture - Idle Cut Off
Switches - OFF

Leaning for all ground operations is vital to keep the mags clear on this
engine. On startup and after exiting the active runway, set RPM to 1000 and
lean slowly for maximum RPM rise. This will often be about 100. Lean
slightly past until RPM just starts to fall. If the engine runs a hair
rough, that's OK. It will be lean enough that it will start to stumble and
quit if you try to run it faster than about 1300. This means you can't
accidentally take off with it leaned.

Since we started doing this, I have only had to clear a mag a couple of
times in two years.

Roger Long

Roger, when you say "clear a mag" do you mean clearing plugs? Because
it isn't the mag that fouls, is it? Isn't it the plugs?

Thanks, Corky Scott

Yes, it is the plugs. Since you switch a mag off people often say clearing
a mag even though it's sort of like saying "digging a shovel".

Mags do foul for very different reasons but the only way to clear them is
with a wallet.

--
Roger Long

Roger, when you say "clear a mag" do you mean clearing plugs? Because
it isn't the mag that fouls, is it? Isn't it the plugs?

Thanks, Corky Scott