Burning out a Magneto Drop

[O. Sami Saydjari]

I just received a booklet from TCM called "Tips on Engine Care" (a very
good book...available from TCM's website...http://www.tcmlink.com/). On
page 12 it says "Never but never attempt to "burn out" a magneto drop
with ground run-up. This 'time-honored' procedure succeeds only at the
expense of the engine's mechanical health."

Well, I was taught this time-honored way. What the book does not say is
what you are supposed to do when you get roughness in one magento. Ideas?

-Sami
N2057M, Piper Turbo Arrow III

[C J Campbell]

"O. Sami Saydjari" > wrote in message
...
> I just received a booklet from TCM called "Tips on Engine Care" (a very
> good book...available from TCM's website...http://www.tcmlink.com/). On
> page 12 it says "Never but never attempt to "burn out" a magneto drop
> with ground run-up. This 'time-honored' procedure succeeds only at the
> expense of the engine's mechanical health."
>
> Well, I was taught this time-honored way. What the book does not say is
> what you are supposed to do when you get roughness in one magento. Ideas?

Really? Does the book say how this will hurt the engine's mechanical health?
To be honest, this "time-honored procedure" seems to have no effect
whatsoever on whether engines make it to TBO or beyond.

[O. Sami Saydjari]

The implication in the book is that it will overheat the engine because
it will cause one to run the engine at high RPM on the ground where
airflow is not as good as in the air. They want you to minimize
high-RPM ground operations.
_sami

C J Campbell wrote:

> "O. Sami Saydjari" > wrote in message
> ...
>
>>I just received a booklet from TCM called "Tips on Engine Care" (a very
>>good book...available from TCM's website...http://www.tcmlink.com/). On
>>page 12 it says "Never but never attempt to "burn out" a magneto drop
>>with ground run-up. This 'time-honored' procedure succeeds only at the
>>expense of the engine's mechanical health."
>>
>>Well, I was taught this time-honored way. What the book does not say is
>>what you are supposed to do when you get roughness in one magento. Ideas?
>
>
> Really? Does the book say how this will hurt the engine's mechanical health?
> To be honest, this "time-honored procedure" seems to have no effect
> whatsoever on whether engines make it to TBO or beyond.
>
>

[Paul Folbrecht]

You can burn off a mag with as little as 1700 rpm for just a couple
minutes.. surely this isn't hurting anything, at least not during the
cooler months.

O. Sami Saydjari wrote:
> The implication in the book is that it will overheat the engine because
> it will cause one to run the engine at high RPM on the ground where
> airflow is not as good as in the air. They want you to minimize
> high-RPM ground operations.
> _sami
>
> C J Campbell wrote:
>
>> "O. Sami Saydjari" > wrote in message
>> ...
>>
>>> I just received a booklet from TCM called "Tips on Engine Care" (a very
>>> good book...available from TCM's website...http://www.tcmlink.com/). On
>>> page 12 it says "Never but never attempt to "burn out" a magneto drop
>>> with ground run-up. This 'time-honored' procedure succeeds only at the
>>> expense of the engine's mechanical health."
>>>
>>> Well, I was taught this time-honored way. What the book does not say is
>>> what you are supposed to do when you get roughness in one magento.
>>> Ideas?
>>
>>
>>
>> Really? Does the book say how this will hurt the engine's mechanical
>> health?
>> To be honest, this "time-honored procedure" seems to have no effect
>> whatsoever on whether engines make it to TBO or beyond.
>>
>>
>

[jls]

"O. Sami Saydjari" > wrote in message
...
> I just received a booklet from TCM called "Tips on Engine Care" (a very
> good book...available from TCM's website...http://www.tcmlink.com/). On
> page 12 it says "Never but never attempt to "burn out" a magneto drop
> with ground run-up. This 'time-honored' procedure succeeds only at the
> expense of the engine's mechanical health."
>
> Well, I was taught this time-honored way. What the book does not say is
> what you are supposed to do when you get roughness in one magento. Ideas?
>
> -Sami
> N2057M, Piper Turbo Arrow III
>

When you lean your engine and rev it up on the ground you are super-heating
the heads, the sparkplugs, the pistons, the valves, seats, and guides ---
just to clean a fouled plug or two by burning the lead or carbon fouling off
the electrode. It's best to clean the fouled plug. Of course, the problem
is NOT with the mag.

My instructor (who was not at all a gearhead) once did that burn-it-off
thing in a 152's O-235 Lycoming, and it wasn't long before that engine was
in the shop for new cylinders. I remember well the heat. We could feel
it and smell it coming through the firewall, and being a gearhead I knew
that THAT was not good for that engine. Besides, an aircraft revved up on
the ground can hardly cool itself, irrespective of the fact you have leaned
the **** out of it.

I haven't seen it but have heard of burning holes in pistons by overleaning.

By the mag drop you already know which set of plugs, upper or lower, and
then all you have to do is find the misfiring cold cylinder. That's easy
enough and what if the problem is a sparkplug wire or injector? You've just
managed to fry your cylinders in the hopes of getting one out of four or six
to fire.

Leaning an engine takes a little finesse. It shouldn't be done on the
ground unless you're in Denver or on a high-altitude ramp. A small fraction
of that fuel charge is cooling your heads as it evaporates and flows through
the combustion chamber and out the exhaust port. Ideally it is rich enough
to give you a perfect stoichiometric charge plus just a little for cooling.
If you burn it all by leaning you have lost your mixture's ability to
dissipate heat. In addition, some of a lean charge is burning as it
departs the combustion chamber because a lean mixture burns more slowly than
a rich one. Damned if I want my exhaust valve to glow just to clean a
sparkplug.

[C J Campbell]

" jls" > wrote in message
...
>
> Leaning an engine takes a little finesse. It shouldn't be done on the
> ground unless you're in Denver or on a high-altitude ramp. A small
fraction
> of that fuel charge is cooling your heads as it evaporates and flows
through
> the combustion chamber and out the exhaust port. Ideally it is rich
enough
> to give you a perfect stoichiometric charge plus just a little for
cooling.
> If you burn it all by leaning you have lost your mixture's ability to
> dissipate heat. In addition, some of a lean charge is burning as it
> departs the combustion chamber because a lean mixture burns more slowly
than
> a rich one. Damned if I want my exhaust valve to glow just to clean a
> sparkplug.

I think you are exaggerating. More than a little bit. I guarantee that even
at sea level you are going to get spark plug fouling if you do not lean your
engine somewhat during taxi -- especially when taxiing in. You just
completed a descent with the mixture full rich and the engine idling -- lots
of cooling and plenty of opportunity for spark plug buildup. I suspect that
the detonation and premature ignition that result from your recommendations
are even harder on an engine than occasionally clearing a spark plug.

[jls]

"C J Campbell" > wrote in message
...
>
> " jls" > wrote in message
> ...
> >
> > Leaning an engine takes a little finesse. It shouldn't be done on the
> > ground unless you're in Denver or on a high-altitude ramp. A small
> fraction
> > of that fuel charge is cooling your heads as it evaporates and flows
> through
> > the combustion chamber and out the exhaust port. Ideally it is rich
> enough
> > to give you a perfect stoichiometric charge plus just a little for
> cooling.
> > If you burn it all by leaning you have lost your mixture's ability to
> > dissipate heat. In addition, some of a lean charge is burning as it
> > departs the combustion chamber because a lean mixture burns more slowly
> than
> > a rich one. Damned if I want my exhaust valve to glow just to clean a
> > sparkplug.
>
> I think you are exaggerating.

Yeah, I don't know if the exhaust valve glows or not but I know when one
gets too hot and don't plan to let it happen to my engine.

More than a little bit. I guarantee that even
> at sea level you are going to get spark plug fouling if you do not lean
your
> engine somewhat during taxi -- especially when taxiing in. You just
> completed a descent with the mixture full rich and the engine idling --
lots
> of cooling and plenty of opportunity for spark plug buildup.

I don't see any big problem with leaning as you taxi. We lean sometimes on
descent and will often lean if an engine tends to miss or surge. It
depends on the engine and airplane too. Leaning at idle, or close to it,
as in when you are taxiing, won't fry your cylinders. But leaning at high
static rpm's will, sooner or later. Thus the reason for TCM's advice not
to do it.

I suspect that
> the detonation and premature ignition that result from your
recommendations
> are even harder on an engine than occasionally clearing a spark plug.

Explain what recommendations I have given which will cause detonation and
premature ignition. Fuel of the improper octane, engine hot spots,
improper leaning and engine conditions I am generally opposed to cause
detonation and preignition. See, e. g.,
http://www.sacskyranch.com/eng180.htm

[jls]

"C J Campbell" > wrote in message
...
[...] I suspect that
> the detonation and premature ignition that result from your
recommendations
> are even harder on an engine than occasionally clearing a spark plug.

Here's an even better link to clear up the confusion:

http://www.sacskyranch.com/deton.htm

And I always wondered why combustion chambers in angle-valve engines were so
clean. I just learned some of the reasons why. They burn cleaner.

[Matthew P. Cummings]

On Sat, 28 Feb 2004 08:11:03 -0800, C J Campbell wrote:

> I think you are exaggerating. More than a little bit. I guarantee that even
> at sea level you are going to get spark plug fouling if you do not lean your
> engine somewhat during taxi -- especially when taxiing in. You just

Very true, and it sounds like the 152 he's talking about got cooked, not
leaned to burn off plug fouling which doesn't take that long.

[jim]

I have no problem burning off a fouled plug, just like last night. Left,
lower plug, seems to be a problem. Another pilot says it is a problem
that shows up just after re-fueling and you prime before a re-start.

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O. Sami Saydjari > wrote:
> I just received a booklet from TCM called "Tips on Engine Care" (a very
> good book...available from TCM's website...http://www.tcmlink.com/). On
> page 12 it says "Never but never attempt to "burn out" a magneto drop
> with ground run-up. This 'time-honored' procedure succeeds only at the
> expense of the engine's mechanical health."

> Well, I was taught this time-honored way. What the book does not say is
> what you are supposed to do when you get roughness in one magento. Ideas?

> -Sami
> N2057M, Piper Turbo Arrow III

Sounds to me like they are trying to err on the side of caution.

John Deakin's series of articles are a worthwhile read; the first is here:
http://www.avweb.com/news/columns/182179-1.html

Of course, you have to have an injected and instrumented (EGT and CHT) engine
to use his advice.

--
Jim Pennino

Remove -spam-sux to reply.

[Ben Jackson]

In article >,
O. Sami Saydjari > wrote:
>
>Well, I was taught this time-honored way. What the book does not say is
>what you are supposed to do when you get roughness in one magento. Ideas?

If you lean aggressively during taxi and avoid full-rich descents you
probably won't have any fouled plugs to worry about (we are talking about
OWNED aircraft, right?). And then engine roughness on the mag check is
probably NOT plugs, so why abuse the engine to try and fix it?

--
Ben Jackson
>
http://www.ben.com/

[Stu Gotts]

Obviously not someone who is familiar with GAMI Injectors or the
Advanced Pilot Seminar where they have data to say opposite!

Contrary to what the self proclaimed gear head states here, your
engine should always be leaned when on the ground to avoid the fouling
that gives you the roughness when one mag is switched off during
runup.

On Sat, 28 Feb 2004 10:37:00 -0500, " jls" >
wrote:

>When you lean your engine and rev it up on the ground you are super-heating
>the heads, the sparkplugs, the pistons, the valves, seats, and guides ---
>just to clean a fouled plug or two by burning the lead or carbon fouling off
>the electrode. It's best to clean the fouled plug. Of course, the problem
>is NOT with the mag.
>
>My instructor (who was not at all a gearhead) once did that burn-it-off
>thing in a 152's O-235 Lycoming, and it wasn't long before that engine was
>in the shop for new cylinders. I remember well the heat. We could feel
>it and smell it coming through the firewall, and being a gearhead I knew
>that THAT was not good for that engine. Besides, an aircraft revved up on
>the ground can hardly cool itself, irrespective of the fact you have leaned
>the **** out of it.
>
>I haven't seen it but have heard of burning holes in pistons by overleaning.
>
>By the mag drop you already know which set of plugs, upper or lower, and
>then all you have to do is find the misfiring cold cylinder. That's easy
>enough and what if the problem is a sparkplug wire or injector? You've just
>managed to fry your cylinders in the hopes of getting one out of four or six
>to fire.
>
>Leaning an engine takes a little finesse. It shouldn't be done on the
>ground unless you're in Denver or on a high-altitude ramp. A small fraction
>of that fuel charge is cooling your heads as it evaporates and flows through
>the combustion chamber and out the exhaust port. Ideally it is rich enough
>to give you a perfect stoichiometric charge plus just a little for cooling.
>If you burn it all by leaning you have lost your mixture's ability to
>dissipate heat. In addition, some of a lean charge is burning as it
>departs the combustion chamber because a lean mixture burns more slowly than
>a rich one. Damned if I want my exhaust valve to glow just to clean a
>sparkplug.
>

[Paul Folbrecht]

BTW, since my FBO started using some fuel additive (sorry- I don't know
what it is offhand) they've experienced NO plug fouling. I can
corraborate that based on 30+ hours of flying since then- not one plug
fouling whereas it used to be quite common (and, yeah, we always burned
it off).

O. Sami Saydjari wrote:
> I just received a booklet from TCM called "Tips on Engine Care" (a very
> good book...available from TCM's website...http://www.tcmlink.com/). On
> page 12 it says "Never but never attempt to "burn out" a magneto drop
> with ground run-up. This 'time-honored' procedure succeeds only at the
> expense of the engine's mechanical health."
>
> Well, I was taught this time-honored way. What the book does not say is
> what you are supposed to do when you get roughness in one magento. Ideas?
>
> -Sami
> N2057M, Piper Turbo Arrow III
>

[O. Sami Saydjari]

Ben, Yeah. Actually, this has not yet happened in the Piper Turbo
Arrow III that I just bought. It happened pretty frequently in the
Skyhawk Millenium that I used to rent. I am asking because the TCM
booklet seems to be pretty hard-over on NOT doing burn-out procedure.

-Sami

Ben Jackson wrote:
> In article >,
> O. Sami Saydjari > wrote:
>
>>Well, I was taught this time-honored way. What the book does not say is
>>what you are supposed to do when you get roughness in one magento. Ideas?
>
>
> If you lean aggressively during taxi and avoid full-rich descents you
> probably won't have any fouled plugs to worry about (we are talking about
> OWNED aircraft, right?). And then engine roughness on the mag check is
> probably NOT plugs, so why abuse the engine to try and fix it?
>

[O. Sami Saydjari]

> It's best to clean the fouled plug. Of course, the problem
> is NOT with the mag.
>


Does that mean that you would shut your airplane down in the run up
area, get out, open the cowling (top and bottom), get out your tool box,
pull the spark plug and clean it on the spot right there? That might
look a little odd, especially at a busy airport. Perhaps I am not
understanding you correctly.

-Sami

[jls]

"O. Sami Saydjari" > wrote in message
...
> > It's best to clean the fouled plug. Of course, the problem
> > is NOT with the mag.
> >
>
>
> Does that mean that you would shut your airplane down in the run up
> area, get out, open the cowling (top and bottom), get out your tool box,
> pull the spark plug and clean it on the spot right there? That might
> look a little odd, especially at a busy airport. Perhaps I am not
> understanding you correctly.
>
> -Sami

Obviously you don't work on your own airplane. Fry it if you like, and in
spite of warnings from TCM.

The previous poster talked about an additive. If you've read all that has
been said (other than some jabbering) and the two Sacramento Sky Ranch
links, you probably have a few ideas about prevention, including the legal
additive, Alcor TCP. It is an old formula quite successfully used in auto
gasoline way back when to prevent lead fouling of sparkplugs.

[O. Sami Saydjari]

jls wrote:
> "O. Sami Saydjari" > wrote in message
> ...
>
>>>It's best to clean the fouled plug. Of course, the problem
>>>is NOT with the mag.
>>>
>>
>>
>>Does that mean that you would shut your airplane down in the run up
>>area, get out, open the cowling (top and bottom), get out your tool box,
>>pull the spark plug and clean it on the spot right there? That might
>>look a little odd, especially at a busy airport. Perhaps I am not
>>understanding you correctly.
>>
>>-Sami
>
>
> Obviously you don't work on your own airplane. Fry it if you like, and in
> spite of warnings from TCM.

Well, I was not trying to be sarcastic, I was just asking a stratight
question about what exactly you were suggesting one do if one is running
up his plane and encountered this situation. I honestly could not tell
from your post, what alternative you were suggesting.

Other than prevention, I have not yet heard a good alternative on the
thread yet. Perhaps I am being dense.

>
> The previous poster talked about an additive. If you've read all that has
> been said (other than some jabbering) and the two Sacramento Sky Ranch
> links, you probably have a few ideas about prevention, including the legal
> additive, Alcor TCP. It is an old formula quite successfully used in auto
> gasoline way back when to prevent lead fouling of sparkplugs.
>
>

[Jim Weir]

Hey, don't worry about it. We get anal retentive engineer types in here from
time to time.

They either suck back in to the wisdom we've collected over the past few years
or have eventually disappeared back into their own wrong groups.

Welcome, if you choose to stay as a member of this group...


" jls" >
shared these priceless pearls of wisdom:

-
->When you lean your engine and rev it up on the ground you are super-heating
->the heads, the sparkplugs, the pistons, the valves, seats, and guides ---
->just to clean a fouled plug or two by burning the lead or carbon fouling off
->the electrode. It's best to clean the fouled plug. Of course, the problem
->is NOT with the mag.

Jim Weir (A&P/IA, CFI, & other good alphabet soup)
VP Eng RST Pres. Cyberchapter EAA Tech. Counselor
http://www.rst-engr.com

[Dennis O'Connor]

For a fouled plug, running up and leaning is an old <as old as aviation>,
and very proven, method of clearing the plug <I have been doing it for a
half century, works for me>...
If it doesn't clear, then you taxi back in and have it serviced...
As far as all the dire warnings from the manufacturers, if you followed
their SB's to the letter, you literally would not be able to fly... Those
SB's are often cya position papers crafted by their legal department, not
engineer recommendations...

cheers ... denny

"O. Sami Saydjari"

[Gene Seibel]

Having to clear an occasional fouled plug is much different than doing
it on a regular basis. If it's a regular thing, I'd find out what the
problem is. If it's once in a great while, I wouldn't worry a bit.

Used to have fouled plugs in my TriPacer when I first bought it. I was
flying in New Mexico where we flew at 9 to 10 thousand feet MSL and
always leaned. I was going full rich when beginning my descent and at
the next startup it'd be rough. Found that if I richened the mixture
gradually as I decended, it never happened.
--
Gene Seibel
Hangar 131 - http://pad39a.com/gene/plane.html
Because I fly, I envy no one.



"O. Sami Saydjari" > wrote in message >...
> I just received a booklet from TCM called "Tips on Engine Care" (a very
> good book...available from TCM's website...http://www.tcmlink.com/). On
> page 12 it says "Never but never attempt to "burn out" a magneto drop
> with ground run-up. This 'time-honored' procedure succeeds only at the
> expense of the engine's mechanical health."
>
> Well, I was taught this time-honored way. What the book does not say is
> what you are supposed to do when you get roughness in one magento. Ideas?
>
> -Sami
> N2057M, Piper Turbo Arrow III

[JerryK]

"C J Campbell" > wrote in message
...
>
> " jls" > wrote in message
>You just
> completed a descent with the mixture full rich and the engine idling --
lots
> of cooling and plenty of opportunity for spark plug buildup.

A good reason to to enrichen the mixture on descent and landing. I always
go as lean as I can.


> I suspect that
> the detonation and premature ignition that result from your
recommendations
> are even harder on an engine than occasionally clearing a spark plug.
>
No doubt!

[Roger Long]

> Leaning an engine takes a little finesse. It shouldn't be done on the
> ground unless you're in Denver or on a high-altitude ramp.

Woah! Don't spread this idea around! No amount of leaning can hurt your
engine at the low power that is usable on the ground. Most engines we fly
were designed for a different fuel and will foul if not leaned on the
ground. It isn't just the sparkplugs. The lead is building up on the valve
guides making them stick and putting strain on the valve train.

You want to lean on the ground so the engine will die if you try to run at
RPM above 1300 - 1500. That way you can't takeoff in a leaned condition
where you could hurt the engine at full power.

Leaning aggressively on the ground will minimize the plug fouling that
requires clearing mags.

--
Roger Long

[jls]

"Roger Long" m> wrote in
message .. .
> > Leaning an engine takes a little finesse. It shouldn't be done on the
> > ground unless you're in Denver or on a high-altitude ramp.
>
> Woah! Don't spread this idea around! No amount of leaning can hurt your
> engine at the low power that is usable on the ground. Most engines we fly
> were designed for a different fuel and will foul if not leaned on the
> ground. It isn't just the sparkplugs. The lead is building up on the
valve
> guides making them stick and putting strain on the valve train.
>
> You want to lean on the ground so the engine will die if you try to run at
> RPM above 1300 - 1500. That way you can't takeoff in a leaned condition
> where you could hurt the engine at full power.
>
> Leaning aggressively on the ground will minimize the plug fouling that
> requires clearing mags.
>
> --
> Roger Long

You are correct and if you had read along further in the thread's early
messages you would see that I clarified this statement, which was related to
clearing an engine by revving it up and leaning by pulling the mixture
control on the ground.