Author: Gary Zilik <zilik@...> Time: Thu Dec 2, 2004 12:48 pm PST Link
A couple of weeks ago I wrote about my rough engine which resulted in a
precautionary (forced) landing. The discussion on the lists were great
with as many personal replies as there were list replies. Amazing as it
may seem Carb Ice was the number 1 suggested reason for my sick lycoming.
Of course carb ice is also one of the hardest to prove since the suspect
leaves the scene of the crime in a timely fashion. Since I do not have a
Carb Air Temp, Iceman or video camera mounted in my carb I must rely on
other instrumentation; RPM and MAP. It is my understanding that on a
constant speed equipped engine that the first indication of carb ice is
lower MP along with reduced IAS due to the power reduction caused by the
lower manifold pressure. The prop will also reduce pitch to keep the RPM
from dropping. This is exactly how it appeared on the 182A that I flew
before building my RV. Engine roughness only occurred after applying
carb heat and the resulting water/ice passing through the engine caused
the roughness. There was never any engine roughness associated with the
carb ice before carb heat was applied. If I'm way off here, someone
please educate me.
Second on the list was water in the fuel. Since I had just refueled
(32.3 gallons) this was a viable source for engine roughness/stoppage. I
had sumped the tanks but as we all know this may not be a thorough
enough check. The fuel has since been checked again and again for water.
Also no water was found in the carb bowl. Quality of the fuel has not
been checked and could have been a bad batch.
Since I seemed to think it was mixture related I thought it could be
tied to the carburetor. I borrowed the new MA-4-5 from the new lycoming
sitting in my shop and bolted it to the bottom of my engine. The damn
thing pissed so much fuel from a stuck float or fod in the needle/seat
that this was a bum test. Since it is not my carb I could not pull the
bowl to check the condition. This carb is heading back to precision for
warranty work. My carburetor has been cleaned, inspected and reassemble
with new gaskets and needle/seat. Nothing out of the ordinary was found.
I now have a nice shiny clean carburetor to install.
Now for the major things I have checked.
The carb as outlined above.
Valve wobble. I had originally checked this in a rather crude method
that I will not divulge here. I went ahead and purchased a wobble check
fixture and checked wobble this past weekend. Wobble is in the range of
.010 - .013 for the 4 cylinders. The acceptable range is .010 - .030
Differential compression. Done on a cold engine and was (1)77/80
(3)77/80 (2)76/80 (4)77/80.
Spark plugs. Left mag is a slick impulse-coupled firing aviation plugs
on the tops of 1 and 3 and the bottoms on 2 and 3. The right is a
Electro-air running automotive plugs on the bottom of 1 and 3 and the
tops on 2 and 4. Both ignition systems ran ran the same (rough) during
the last episode. All plugs looked normal except for the bottom aviation
plug on number 2 cylinder. The center electrode was leaning towards one
side. A normal plug after running has a football shaped center electrode
and looks like this (0) when viewed for gapping. Now imagine the center
electrode leaning upwards almost closing the gap on the outside
electrodes. My thoughts were excessive heat. Detonation?
Cylinders/pistions. All look normal except for #2. It looks as if the
carbon on the top of the piston has been blasted off, or changed color
to a light tan. Again my thoughts lean towards excessive heat. I'm still
looking for a borescope to borrow beg or steal.
Mag timing. checked and is ok. One suggestion was that the EI on the
right may be advancing the spark to maximum due to a failed/failing MAP
sensor. This could cause preignition leading towards detonation. The MAP
sensor has not been checked but is on my list of things to check.
Baffles. I found a small chunk (1.0 x 0.5") missing in the right bottom
corner of the left inlet ramp (due to cracking) This is the inlet in
front of #2. I also have a plenum and the baffling material around the
inlet on this side was split along the top. Since I have never liked the
aluminum plenum top I have removed the plenum and replace with
standard baffle/cowl seals and fixed all irregularities in the baffles
including replacing the inlet ramp on number 2 cylinder. The top cowl is
at home getting the top inlet ramp smoothing thingies glassed in.
Conclusion: I have gone over the major items looked at and skipped the
many little items. While valve sticking could be the culprit the valves
pass the wobble check as per Lycomings specifications. While they fall
in the low end of the specified limits for valve wobble they are within
limits. #2 cylinder bothers me because of the funny looking spark plug
and the clean looking piston. Hotspots formed by cracked and leaking
baffles could have caused preignition/detenation in cyl 2. See
http://www.avweb.com/news/columns/182132-1.html for more information on
detonation.
Part of me wants to pull the cylinders and take a good look inside.
Would it be a waste of money? Not if it gives me good piece of mind
while flying over the Rockies. I'm also thinking about installing a JPI
EDM-700 or Insights GEM 610 so I can monitor all cht/egt with recording
functions. This may be too much information most of the time but when
engine problems arise I can see how it can be a great diagnostic tool.
I'm also an aggressive leaner. Since my wife bought me a Fuel flow
computer I have a tendency to lean, lean, lean trying to get the fuel
flow down. I'm thinking this is not a good thing.
Items that have been checked:
Water or improper fuel
Ignition timing
Carburator
Fuel flow and pressure
valve wobble check
restrictions in the intake system
diff compression check
Replaced plugs with clean refurbished plugs
ignition leads (with a lead tester)
Things that have been changed:
plugs
carburator
major mods to baffling
Things left to check:
EI MAP sensor
intake tube rubber hoses
and anything else I can think of.
Gary
------------------------ Yahoo! Groups Sponsor --------------------~-->
Make a clean sweep of pop-up ads. Yahoo! Companion Toolbar.
Now with Pop-Up Blocker. Get it for free!
http://us.click.yahoo.com/L5YrjA/eSIIAA/yQLSAA/1yWplB/TM
--------------------------------------------------------------------~->
Online help on this group at:
http://help.yahoo.com/help/groups/
Yahoo! Groups Links
<*> To visit your group on the web, go to:
http://groups.yahoo.com/group/vansairforce/
<*> To unsubscribe from this group, send an email to:
vansairforce-unsubscribe@yahoogroups.com
<*> Your use of Yahoo! Groups is subject to:
http://docs.yahoo.com/info/terms/
Author: Charles Kuss <chaskuss@...> Time: Thu Dec 2, 2004 1:56 pm PST Link
Gary,
Read the ElectroAir manual. You can jumper one (red?)
wire to ground. This will defeat the electronic
advance. The ElectroAir will then function like a
magneto and only advance to 25 degrees. This is an
easy way to eliminate the MAP sensor as the problem.
Jeff sells an optional display screen to mount in the
instrument panel. It shows the electronic advance in
degrees before top dead center.
Charlie Kuss
--- Gary Zilik <zilik@direcpc.com> wrote:
> A couple of weeks ago I wrote about my rough engine
> which resulted in a
> precautionary (forced) landing. The discussion on
> the lists were great
> with as many personal replies as there were list
> replies. Amazing as it
> may seem Carb Ice was the number 1 suggested reason
> for my sick lycoming.
>
> Of course carb ice is also one of the hardest to
> prove since the suspect
> leaves the scene of the crime in a timely fashion.
> Since I do not have a
> Carb Air Temp, Iceman or video camera mounted in my
> carb I must rely on
> other instrumentation; RPM and MAP. It is my
> understanding that on a
> constant speed equipped engine that the first
> indication of carb ice is
> lower MP along with reduced IAS due to the power
> reduction caused by the
> lower manifold pressure. The prop will also reduce
> pitch to keep the RPM
> from dropping. This is exactly how it appeared on
> the 182A that I flew
> before building my RV. Engine roughness only
> occurred after applying
> carb heat and the resulting water/ice passing
> through the engine caused
> the roughness. There was never any engine roughness
> associated with the
> carb ice before carb heat was applied. If I'm way
> off here, someone
> please educate me.
>
> Second on the list was water in the fuel. Since I
> had just refueled
> (32.3 gallons) this was a viable source for engine
> roughness/stoppage. I
> had sumped the tanks but as we all know this may not
> be a thorough
> enough check. The fuel has since been checked again
> and again for water.
> Also no water was found in the carb bowl. Quality of
> the fuel has not
> been checked and could have been a bad batch.
>
> Since I seemed to think it was mixture related I
> thought it could be
> tied to the carburetor. I borrowed the new MA-4-5
> from the new lycoming
> sitting in my shop and bolted it to the bottom of my
> engine. The damn
> thing pissed so much fuel from a stuck float or fod
> in the needle/seat
> that this was a bum test. Since it is not my carb I
> could not pull the
> bowl to check the condition. This carb is heading
> back to precision for
> warranty work. My carburetor has been cleaned,
> inspected and reassemble
> with new gaskets and needle/seat. Nothing out of the
> ordinary was found.
> I now have a nice shiny clean carburetor to install.
>
> Now for the major things I have checked.
>
> The carb as outlined above.
>
> Valve wobble. I had originally checked this in a
> rather crude method
> that I will not divulge here. I went ahead and
> purchased a wobble check
> fixture and checked wobble this past weekend. Wobble
> is in the range of
> .010 - .013 for the 4 cylinders. The acceptable
> range is .010 - .030
>
> Differential compression. Done on a cold engine and
> was (1)77/80
> (3)77/80 (2)76/80 (4)77/80.
>
> Spark plugs. Left mag is a slick impulse-coupled
> firing aviation plugs
> on the tops of 1 and 3 and the bottoms on 2 and 3.
> The right is a
> Electro-air running automotive plugs on the bottom
> of 1 and 3 and the
> tops on 2 and 4. Both ignition systems ran ran the
> same (rough) during
> the last episode. All plugs looked normal except for
> the bottom aviation
> plug on number 2 cylinder. The center electrode was
> leaning towards one
> side. A normal plug after running has a football
> shaped center electrode
> and looks like this (0) when viewed for gapping. Now
> imagine the center
> electrode leaning upwards almost closing the gap on
> the outside
> electrodes. My thoughts were excessive heat.
> Detonation?
>
> Cylinders/pistions. All look normal except for #2.
> It looks as if the
> carbon on the top of the piston has been blasted
> off, or changed color
> to a light tan. Again my thoughts lean towards
> excessive heat. I'm still
> looking for a borescope to borrow beg or steal.
>
> Mag timing. checked and is ok. One suggestion was
> that the EI on the
> right may be advancing the spark to maximum due to a
> failed/failing MAP
> sensor. This could cause preignition leading towards
> detonation. The MAP
> sensor has not been checked but is on my list of
> things to check.
>
> Baffles. I found a small chunk (1.0 x 0.5") missing
> in the right bottom
> corner of the left inlet ramp (due to cracking) This
> is the inlet in
> front of #2. I also have a plenum and the baffling
> material around the
> inlet on this side was split along the top. Since I
> have never liked the
> aluminum plenum top I have removed the plenum and
> replace with
> standard baffle/cowl seals and fixed all
> irregularities in the baffles
> including replacing the inlet ramp on number 2
> cylinder. The top cowl is
> at home getting the top inlet ramp smoothing
> thingies glassed in.
>
> Conclusion: I have gone over the major items looked
> at and skipped the
> many little items. While valve sticking could be the
> culprit the valves
> pass the wobble check as per Lycomings
> specifications. While they fall
> in the low end of the specified limits for valve
> wobble they are within
> limits. #2 cylinder bothers me because of the funny
> looking spark plug
> and the clean looking piston. Hotspots formed by
> cracked and leaking
> baffles could have caused preignition/detenation in
> cyl 2. See
> http://www.avweb.com/news/columns/182132-1.html for
> more information on
> detonation.
>
> Part of me wants to pull the cylinders and take a
> good look inside.
> Would it be a waste of money? Not if it gives me
> good piece of mind
> while flying over the Rockies. I'm also thinking
> about installing a JPI
> EDM-700 or Insights GEM 610 so I can monitor all
> cht/egt with recording
> functions. This may be too much information most of
> the time but when
> engine problems arise I can see how it can be a
> great diagnostic tool.
> I'm also an aggressive leaner. Since my wife bought
> me a Fuel flow
> computer I have a tendency to lean, lean, lean
> trying to get the fuel
> flow down. I'm thinking this is not a good thing.
>
> Items that have been checked:
> Water or improper fuel
> Ignition timing
> Carburator
> Fuel flow and pressure
> valve wobble check
> restrictions in the intake system
> diff compression check
> Replaced plugs with clean refurbished plugs
> ignition leads (with a lead tester)
>
> Things that have been changed:
> plugs
> carburator
> major mods to baffling
>
> Things left to check:
> EI MAP sensor
> intake tube rubber hoses
>
> and anything else I can think of.
>
> Gary
=== message truncated ===
__________________________________
Do you Yahoo!?
Dress up your holiday email, Hollywood style. Learn more.
http://celebrity.mail.yahoo.com
------------------------ Yahoo! Groups Sponsor --------------------~-->
$9.95 domain names from Yahoo!. Register anything.
http://us.click.yahoo.com/J8kdrA/y20IAA/yQLSAA/1yWplB/TM
--------------------------------------------------------------------~->
Online help on this group at:
http://help.yahoo.com/help/groups/
Yahoo! Groups Links
<*> To visit your group on the web, go to:
http://groups.yahoo.com/group/vansairforce/
<*> To unsubscribe from this group, send an email to:
vansairforce-unsubscribe@yahoogroups.com
<*> Your use of Yahoo! Groups is subject to:
http://docs.yahoo.com/info/terms/
Author: Mike Thompson <grobdriver@...> Time: Thu Dec 2, 2004 7:03 pm PST Link
I have a tendency to lean, lean, lean trying to get the fuel
flow down. I'm thinking this is not a good thing.
To comment on just this one statement: I got concerned about my own leaning practices about 6 months ago and put the question to the list. Got the whole LOP, ROP discussion going.
Two private replies in particular gave me a better feeling about it, both from employees of reputable engine rebuilding shops.
At cruise altitudes, they wrote, where a normally aspirated engine is making 75% or less power at full (redline) RPM, you can't hurt it - can't lean it "too much". Their opinion was that leaning in cruise never burned an exhaust valve, will never cause valve train damage in any way.
So these days I feel good about leaning the way they taught me 25 years ago: lean until rough, enrichen until smooth. And always lean to best power in high density altitude conditions.
Good luck with your resolution!
- Mike
Gary Zilik <zilik@direcpc.com> wrote:
A couple of weeks ago I wrote about my rough engine which resulted in a
precautionary (forced) landing. The discussion on the lists were great
with as many personal replies as there were list replies.
Michael E. Thompson (Grobdriver@yahoo.com)
Austin, TX, USA
RV-6 N140RV, FLYING!
Ex-AX1 Sub Hunter, P-3 (B/B-TACMOD/C) Orion Aircrew,
PP-G,ASEL, Motorglider Driver and Unlimited Air Race Nut!
---------------------------------
Do you Yahoo!?
All your favorites on one personal page – Try My Yahoo!
[Non-text portions of this message have been removed]
------------------------ Yahoo! Groups Sponsor --------------------~-->
$9.95 domain names from Yahoo!. Register anything.
http://us.click.yahoo.com/J8kdrA/y20IAA/yQLSAA/1yWplB/TM
--------------------------------------------------------------------~->
Online help on this group at:
http://help.yahoo.com/help/groups/
Yahoo! Groups Links
<*> To visit your group on the web, go to:
http://groups.yahoo.com/group/vansairforce/
<*> To unsubscribe from this group, send an email to:
vansairforce-unsubscribe@yahoogroups.com
<*> Your use of Yahoo! Groups is subject to:
http://docs.yahoo.com/info/terms/
Author: "Steven L. Hild" <L-of-Louavul@...> Time: Fri Dec 3, 2004 10:53 am PST Link
I have a friend in New Mexico with a -6A that had strange engine
problems due to the fuel tank selector valve.
It seems the valve had become worn internally and would suck air to
the point of the engine becomeing rough and even quiting on
occasion. Strangely the valve did not leak any fuel. As I recall it
was sensitive to which tank it was selected to.
Symptoms are not exactly the same but there are some similiarities.
Felt I should just throw this into the mix for thought.
Steven L. Hild
La Vernia, TX
RV-7 Fuse
--- In vansairforce@yahoogroups.com, Gary Zilik <zilik@d...> wrote:
>
> A couple of weeks ago I wrote about my rough engine which resulted
in a
> precautionary (forced) landing. The discussion on the lists were
great
> with as many personal replies as there were list replies. Amazing
as it
> may seem Carb Ice was the number 1 suggested reason for my sick
lycoming.
>
> Of course carb ice is also one of the hardest to prove since the
suspect
> leaves the scene of the crime in a timely fashion. Since I do not
have a
> Carb Air Temp, Iceman or video camera mounted in my carb I must
rely on
> other instrumentation; RPM and MAP. It is my understanding that on
a
> constant speed equipped engine that the first indication of carb
ice is
> lower MP along with reduced IAS due to the power reduction caused
by the
> lower manifold pressure. The prop will also reduce pitch to keep
the RPM
> from dropping. This is exactly how it appeared on the 182A that I
flew
> before building my RV. Engine roughness only occurred after
applying
> carb heat and the resulting water/ice passing through the engine
caused
> the roughness. There was never any engine roughness associated with
the
> carb ice before carb heat was applied. If I'm way off here, someone
> please educate me.
>
> Second on the list was water in the fuel. Since I had just refueled
> (32.3 gallons) this was a viable source for engine
roughness/stoppage. I
> had sumped the tanks but as we all know this may not be a thorough
> enough check. The fuel has since been checked again and again for
water.
> Also no water was found in the carb bowl. Quality of the fuel has
not
> been checked and could have been a bad batch.
>
> Since I seemed to think it was mixture related I thought it could
be
> tied to the carburetor. I borrowed the new MA-4-5 from the new
lycoming
> sitting in my shop and bolted it to the bottom of my engine. The
damn
> thing pissed so much fuel from a stuck float or fod in the
needle/seat
> that this was a bum test. Since it is not my carb I could not pull
the
> bowl to check the condition. This carb is heading back to precision
for
> warranty work. My carburetor has been cleaned, inspected and
reassemble
> with new gaskets and needle/seat. Nothing out of the ordinary was
found.
> I now have a nice shiny clean carburetor to install.
>
> Now for the major things I have checked.
>
> The carb as outlined above.
>
> Valve wobble. I had originally checked this in a rather crude
method
> that I will not divulge here. I went ahead and purchased a wobble
check
> fixture and checked wobble this past weekend. Wobble is in the
range of
> .010 - .013 for the 4 cylinders. The acceptable range is .010 - .030
>
> Differential compression. Done on a cold engine and was (1)77/80
> (3)77/80 (2)76/80 (4)77/80.
>
> Spark plugs. Left mag is a slick impulse-coupled firing aviation
plugs
> on the tops of 1 and 3 and the bottoms on 2 and 3. The right is a
> Electro-air running automotive plugs on the bottom of 1 and 3 and
the
> tops on 2 and 4. Both ignition systems ran ran the same (rough)
during
> the last episode. All plugs looked normal except for the bottom
aviation
> plug on number 2 cylinder. The center electrode was leaning towards
one
> side. A normal plug after running has a football shaped center
electrode
> and looks like this (0) when viewed for gapping. Now imagine the
center
> electrode leaning upwards almost closing the gap on the outside
> electrodes. My thoughts were excessive heat. Detonation?
>
> Cylinders/pistions. All look normal except for #2. It looks as if
the
> carbon on the top of the piston has been blasted off, or changed
color
> to a light tan. Again my thoughts lean towards excessive heat. I'm
still
> looking for a borescope to borrow beg or steal.
>
> Mag timing. checked and is ok. One suggestion was that the EI on
the
> right may be advancing the spark to maximum due to a failed/failing
MAP
> sensor. This could cause preignition leading towards detonation.
The MAP
> sensor has not been checked but is on my list of things to check.
>
> Baffles. I found a small chunk (1.0 x 0.5") missing in the right
bottom
> corner of the left inlet ramp (due to cracking) This is the inlet
in
> front of #2. I also have a plenum and the baffling material around
the
> inlet on this side was split along the top. Since I have never
liked the
> aluminum plenum top I have removed the plenum and replace with
> standard baffle/cowl seals and fixed all irregularities in the
baffles
> including replacing the inlet ramp on number 2 cylinder. The top
cowl is
> at home getting the top inlet ramp smoothing thingies glassed in.
>
> Conclusion: I have gone over the major items looked at and skipped
the
> many little items. While valve sticking could be the culprit the
valves
> pass the wobble check as per Lycomings specifications. While they
fall
> in the low end of the specified limits for valve wobble they are
within
> limits. #2 cylinder bothers me because of the funny looking spark
plug
> and the clean looking piston. Hotspots formed by cracked and
leaking
> baffles could have caused preignition/detenation in cyl 2. See
> http://www.avweb.com/news/columns/182132-1.html for more
information on
> detonation.
>
> Part of me wants to pull the cylinders and take a good look inside.
> Would it be a waste of money? Not if it gives me good piece of mind
> while flying over the Rockies. I'm also thinking about installing a
JPI
> EDM-700 or Insights GEM 610 so I can monitor all cht/egt with
recording
> functions. This may be too much information most of the time but
when
> engine problems arise I can see how it can be a great diagnostic
tool.
> I'm also an aggressive leaner. Since my wife bought me a Fuel flow
> computer I have a tendency to lean, lean, lean trying to get the
fuel
> flow down. I'm thinking this is not a good thing.
>
> Items that have been checked:
> Water or improper fuel
> Ignition timing
> Carburator
> Fuel flow and pressure
> valve wobble check
> restrictions in the intake system
> diff compression check
> Replaced plugs with clean refurbished plugs
> ignition leads (with a lead tester)
>
> Things that have been changed:
> plugs
> carburator
> major mods to baffling
>
> Things left to check:
> EI MAP sensor
> intake tube rubber hoses
>
> and anything else I can think of.
>
> Gary
------------------------ Yahoo! Groups Sponsor --------------------~-->
$9.95 domain names from Yahoo!. Register anything.
http://us.click.yahoo.com/J8kdrA/y20IAA/yQLSAA/1yWplB/TM
--------------------------------------------------------------------~->
Online help on this group at:
http://help.yahoo.com/help/groups/
Yahoo! Groups Links
<*> To visit your group on the web, go to:
http://groups.yahoo.com/group/vansairforce/
<*> To unsubscribe from this group, send an email to:
vansairforce-unsubscribe@yahoogroups.com
<*> Your use of Yahoo! Groups is subject to:
http://docs.yahoo.com/info/terms/
Author: "Steven L. Hild" <L-of-Louavul@...> Time: Fri Dec 3, 2004 10:53 am PST Link
I have a friend in New Mexico with a -6A that had strange engine
problems due to the fuel tank selector valve.
It seems the valve had become worn internally and would suck air to
the point of the engine becomeing rough and even quiting on
occasion. Strangely the valve did not leak any fuel. As I recall it
was sensitive to which tank it was selected to.
Symptoms are not exactly the same but there are some similiarities.
Felt I should just throw this into the mix for thought.
Steven L. Hild
La Vernia, TX
RV-7 Fuse
--- In vansairforce@yahoogroups.com, Gary Zilik <zilik@d...> wrote:
>
> A couple of weeks ago I wrote about my rough engine which resulted
in a
> precautionary (forced) landing. The discussion on the lists were
great
> with as many personal replies as there were list replies. Amazing
as it
> may seem Carb Ice was the number 1 suggested reason for my sick
lycoming.
>
> Of course carb ice is also one of the hardest to prove since the
suspect
> leaves the scene of the crime in a timely fashion. Since I do not
have a
> Carb Air Temp, Iceman or video camera mounted in my carb I must
rely on
> other instrumentation; RPM and MAP. It is my understanding that on
a
> constant speed equipped engine that the first indication of carb
ice is
> lower MP along with reduced IAS due to the power reduction caused
by the
> lower manifold pressure. The prop will also reduce pitch to keep
the RPM
> from dropping. This is exactly how it appeared on the 182A that I
flew
> before building my RV. Engine roughness only occurred after
applying
> carb heat and the resulting water/ice passing through the engine
caused
> the roughness. There was never any engine roughness associated with
the
> carb ice before carb heat was applied. If I'm way off here, someone
> please educate me.
>
> Second on the list was water in the fuel. Since I had just refueled
> (32.3 gallons) this was a viable source for engine
roughness/stoppage. I
> had sumped the tanks but as we all know this may not be a thorough
> enough check. The fuel has since been checked again and again for
water.
> Also no water was found in the carb bowl. Quality of the fuel has
not
> been checked and could have been a bad batch.
>
> Since I seemed to think it was mixture related I thought it could
be
> tied to the carburetor. I borrowed the new MA-4-5 from the new
lycoming
> sitting in my shop and bolted it to the bottom of my engine. The
damn
> thing pissed so much fuel from a stuck float or fod in the
needle/seat
> that this was a bum test. Since it is not my carb I could not pull
the
> bowl to check the condition. This carb is heading back to precision
for
> warranty work. My carburetor has been cleaned, inspected and
reassemble
> with new gaskets and needle/seat. Nothing out of the ordinary was
found.
> I now have a nice shiny clean carburetor to install.
>
> Now for the major things I have checked.
>
> The carb as outlined above.
>
> Valve wobble. I had originally checked this in a rather crude
method
> that I will not divulge here. I went ahead and purchased a wobble
check
> fixture and checked wobble this past weekend. Wobble is in the
range of
> .010 - .013 for the 4 cylinders. The acceptable range is .010 - .030
>
> Differential compression. Done on a cold engine and was (1)77/80
> (3)77/80 (2)76/80 (4)77/80.
>
> Spark plugs. Left mag is a slick impulse-coupled firing aviation
plugs
> on the tops of 1 and 3 and the bottoms on 2 and 3. The right is a
> Electro-air running automotive plugs on the bottom of 1 and 3 and
the
> tops on 2 and 4. Both ignition systems ran ran the same (rough)
during
> the last episode. All plugs looked normal except for the bottom
aviation
> plug on number 2 cylinder. The center electrode was leaning towards
one
> side. A normal plug after running has a football shaped center
electrode
> and looks like this (0) when viewed for gapping. Now imagine the
center
> electrode leaning upwards almost closing the gap on the outside
> electrodes. My thoughts were excessive heat. Detonation?
>
> Cylinders/pistions. All look normal except for #2. It looks as if
the
> carbon on the top of the piston has been blasted off, or changed
color
> to a light tan. Again my thoughts lean towards excessive heat. I'm
still
> looking for a borescope to borrow beg or steal.
>
> Mag timing. checked and is ok. One suggestion was that the EI on
the
> right may be advancing the spark to maximum due to a failed/failing
MAP
> sensor. This could cause preignition leading towards detonation.
The MAP
> sensor has not been checked but is on my list of things to check.
>
> Baffles. I found a small chunk (1.0 x 0.5") missing in the right
bottom
> corner of the left inlet ramp (due to cracking) This is the inlet
in
> front of #2. I also have a plenum and the baffling material around
the
> inlet on this side was split along the top. Since I have never
liked the
> aluminum plenum top I have removed the plenum and replace with
> standard baffle/cowl seals and fixed all irregularities in the
baffles
> including replacing the inlet ramp on number 2 cylinder. The top
cowl is
> at home getting the top inlet ramp smoothing thingies glassed in.
>
> Conclusion: I have gone over the major items looked at and skipped
the
> many little items. While valve sticking could be the culprit the
valves
> pass the wobble check as per Lycomings specifications. While they
fall
> in the low end of the specified limits for valve wobble they are
within
> limits. #2 cylinder bothers me because of the funny looking spark
plug
> and the clean looking piston. Hotspots formed by cracked and
leaking
> baffles could have caused preignition/detenation in cyl 2. See
> http://www.avweb.com/news/columns/182132-1.html for more
information on
> detonation.
>
> Part of me wants to pull the cylinders and take a good look inside.
> Would it be a waste of money? Not if it gives me good piece of mind
> while flying over the Rockies. I'm also thinking about installing a
JPI
> EDM-700 or Insights GEM 610 so I can monitor all cht/egt with
recording
> functions. This may be too much information most of the time but
when
> engine problems arise I can see how it can be a great diagnostic
tool.
> I'm also an aggressive leaner. Since my wife bought me a Fuel flow
> computer I have a tendency to lean, lean, lean trying to get the
fuel
> flow down. I'm thinking this is not a good thing.
>
> Items that have been checked:
> Water or improper fuel
> Ignition timing
> Carburator
> Fuel flow and pressure
> valve wobble check
> restrictions in the intake system
> diff compression check
> Replaced plugs with clean refurbished plugs
> ignition leads (with a lead tester)
>
> Things that have been changed:
> plugs
> carburator
> major mods to baffling
>
> Things left to check:
> EI MAP sensor
> intake tube rubber hoses
>
> and anything else I can think of.
>
> Gary
------------------------ Yahoo! Groups Sponsor --------------------~-->
$9.95 domain names from Yahoo!. Register anything.
http://us.click.yahoo.com/J8kdrA/y20IAA/yQLSAA/1yWplB/TM
--------------------------------------------------------------------~->
Online help on this group at:
http://help.yahoo.com/help/groups/
Yahoo! Groups Links
<*> To visit your group on the web, go to:
http://groups.yahoo.com/group/vansairforce/
<*> To unsubscribe from this group, send an email to:
vansairforce-unsubscribe@yahoogroups.com
<*> Your use of Yahoo! Groups is subject to:
http://docs.yahoo.com/info/terms/
Author: "Richard & Roberta Hegy" <rhegy@...> Time: Fri Dec 3, 2004 3:50 pm PST Link
Good luck, Gary. Hope you find it. Don't have any other suggestions to offer. Keep us posted on what you find. Keep safe!!!
Roberta
----- Original Message -----
From: Gary Zilik
To: vansairforce@yahoogroups.com ; SoCAL-RVlist ; rv-list@matronics.com
Sent: Thursday, December 02, 2004 2:06 PM
Subject: [VAF Mailing List] Gary Zilik's engine problem update
A couple of weeks ago I wrote about my rough engine which resulted in a
precautionary (forced) landing. The discussion on the lists were great
with as many personal replies as there were list replies. Amazing as it
may seem Carb Ice was the number 1 suggested reason for my sick lycoming.
Of course carb ice is also one of the hardest to prove since the suspect
leaves the scene of the crime in a timely fashion. Since I do not have a
Carb Air Temp, Iceman or video camera mounted in my carb I must rely on
other instrumentation; RPM and MAP. It is my understanding that on a
constant speed equipped engine that the first indication of carb ice is
lower MP along with reduced IAS due to the power reduction caused by the
lower manifold pressure. The prop will also reduce pitch to keep the RPM
from dropping. This is exactly how it appeared on the 182A that I flew
before building my RV. Engine roughness only occurred after applying
carb heat and the resulting water/ice passing through the engine caused
the roughness. There was never any engine roughness associated with the
carb ice before carb heat was applied. If I'm way off here, someone
please educate me.
Second on the list was water in the fuel. Since I had just refueled
(32.3 gallons) this was a viable source for engine roughness/stoppage. I
had sumped the tanks but as we all know this may not be a thorough
enough check. The fuel has since been checked again and again for water.
Also no water was found in the carb bowl. Quality of the fuel has not
been checked and could have been a bad batch.
Since I seemed to think it was mixture related I thought it could be
tied to the carburetor. I borrowed the new MA-4-5 from the new lycoming
sitting in my shop and bolted it to the bottom of my engine. The damn
thing pissed so much fuel from a stuck float or fod in the needle/seat
that this was a bum test. Since it is not my carb I could not pull the
bowl to check the condition. This carb is heading back to precision for
warranty work. My carburetor has been cleaned, inspected and reassemble
with new gaskets and needle/seat. Nothing out of the ordinary was found.
I now have a nice shiny clean carburetor to install.
Now for the major things I have checked.
The carb as outlined above.
Valve wobble. I had originally checked this in a rather crude method
that I will not divulge here. I went ahead and purchased a wobble check
fixture and checked wobble this past weekend. Wobble is in the range of
.010 - .013 for the 4 cylinders. The acceptable range is .010 - .030
Differential compression. Done on a cold engine and was (1)77/80
(3)77/80 (2)76/80 (4)77/80.
Spark plugs. Left mag is a slick impulse-coupled firing aviation plugs
on the tops of 1 and 3 and the bottoms on 2 and 3. The right is a
Electro-air running automotive plugs on the bottom of 1 and 3 and the
tops on 2 and 4. Both ignition systems ran ran the same (rough) during
the last episode. All plugs looked normal except for the bottom aviation
plug on number 2 cylinder. The center electrode was leaning towards one
side. A normal plug after running has a football shaped center electrode
and looks like this (0) when viewed for gapping. Now imagine the center
electrode leaning upwards almost closing the gap on the outside
electrodes. My thoughts were excessive heat. Detonation?
Cylinders/pistions. All look normal except for #2. It looks as if the
carbon on the top of the piston has been blasted off, or changed color
to a light tan. Again my thoughts lean towards excessive heat. I'm still
looking for a borescope to borrow beg or steal.
Mag timing. checked and is ok. One suggestion was that the EI on the
right may be advancing the spark to maximum due to a failed/failing MAP
sensor. This could cause preignition leading towards detonation. The MAP
sensor has not been checked but is on my list of things to check.
Baffles. I found a small chunk (1.0 x 0.5") missing in the right bottom
corner of the left inlet ramp (due to cracking) This is the inlet in
front of #2. I also have a plenum and the baffling material around the
inlet on this side was split along the top. Since I have never liked the
aluminum plenum top I have removed the plenum and replace with
standard baffle/cowl seals and fixed all irregularities in the baffles
including replacing the inlet ramp on number 2 cylinder. The top cowl is
at home getting the top inlet ramp smoothing thingies glassed in.
Conclusion: I have gone over the major items looked at and skipped the
many little items. While valve sticking could be the culprit the valves
pass the wobble check as per Lycomings specifications. While they fall
in the low end of the specified limits for valve wobble they are within
limits. #2 cylinder bothers me because of the funny looking spark plug
and the clean looking piston. Hotspots formed by cracked and leaking
baffles could have caused preignition/detenation in cyl 2. See
http://www.avweb.com/news/columns/182132-1.html for more information on
detonation.
Part of me wants to pull the cylinders and take a good look inside.
Would it be a waste of money? Not if it gives me good piece of mind
while flying over the Rockies. I'm also thinking about installing a JPI
EDM-700 or Insights GEM 610 so I can monitor all cht/egt with recording
functions. This may be too much information most of the time but when
engine problems arise I can see how it can be a great diagnostic tool.
I'm also an aggressive leaner. Since my wife bought me a Fuel flow
computer I have a tendency to lean, lean, lean trying to get the fuel
flow down. I'm thinking this is not a good thing.
Items that have been checked:
Water or improper fuel
Ignition timing
Carburator
Fuel flow and pressure
valve wobble check
restrictions in the intake system
diff compression check
Replaced plugs with clean refurbished plugs
ignition leads (with a lead tester)
Things that have been changed:
plugs
carburator
major mods to baffling
Things left to check:
EI MAP sensor
intake tube rubber hoses
and anything else I can think of.
Gary
Online help on this group at:
http://help.yahoo.com/help/groups/
Yahoo! Groups Sponsor
ADVERTISEMENT
------------------------------------------------------------------------------
Yahoo! Groups Links
a.. To visit your group on the web, go to:
http://groups.yahoo.com/group/vansairforce/
b.. To unsubscribe from this group, send an email to:
vansairforce-unsubscribe@yahoogroups.com
c.. Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.
[Non-text portions of this message have been removed]
------------------------ Yahoo! Groups Sponsor --------------------~-->
Make a clean sweep of pop-up ads. Yahoo! Companion Toolbar.
Now with Pop-Up Blocker. Get it for free!
http://us.click.yahoo.com/L5YrjA/eSIIAA/yQLSAA/1yWplB/TM
--------------------------------------------------------------------~->
Online help on this group at:
http://help.yahoo.com/help/groups/
Yahoo! Groups Links
<*> To visit your group on the web, go to:
http://groups.yahoo.com/group/vansairforce/
<*> To unsubscribe from this group, send an email to:
vansairforce-unsubscribe@yahoogroups.com
<*> Your use of Yahoo! Groups is subject to:
http://docs.yahoo.com/info/terms/
Author: David Brand <dbrandx@...> Time: Mon Dec 6, 2004 3:37 am PST Link
Gary,
Wow, sounds like you`ve really dug into this. I don`t think I could add
much to what everybody has already advised, so I won`t go there. I do,
however have an opinion about the EGT/CHT analyzer. I flew my Bonanza for
years with an old Alcor six probe EGT. You`ve probably seen these in years
past. Little single needle dial with a rotating switch to select each
cylinder. Always worked just fine. One day, after flying a five day trip,
cooped up in the cockpit of a Boeing, with a fellow Bonanza owner, who had
an analyzer installed in his machine, I decided to take his advice and try
an EDM-700. It seemed pretty spendy at the time, about $1800 or so, and
was pretty much an all day project to install. It took a little getting
used to as well, but now, I can`t imagine being without it. When I was
outfitting the panel of my -8, there was no question that I was also going
to have the same thing. I highly recommend you do the same, especially
since you`re an agressive leaner. Nothing beats having all the info right
there all the time.
Dave Brand N254LF
--- Gary Zilik
<zilik@direcpc.com> wrote:
> A couple of weeks ago I wrote about my rough engine which resulted in a
> precautionary (forced) landing. The discussion on the lists were great
> with as many personal replies as there were list replies. Amazing as it
> may seem Carb Ice was the number 1 suggested reason for my sick
> lycoming.
>
> Of course carb ice is also one of the hardest to prove since the suspect
>
> leaves the scene of the crime in a timely fashion. Since I do not have a
>
> Carb Air Temp, Iceman or video camera mounted in my carb I must rely on
> other instrumentation; RPM and MAP. It is my understanding that on a
> constant speed equipped engine that the first indication of carb ice is
> lower MP along with reduced IAS due to the power reduction caused by the
>
> lower manifold pressure. The prop will also reduce pitch to keep the RPM
>
> from dropping. This is exactly how it appeared on the 182A that I flew
> before building my RV. Engine roughness only occurred after applying
> carb heat and the resulting water/ice passing through the engine caused
> the roughness. There was never any engine roughness associated with the
> carb ice before carb heat was applied. If I'm way off here, someone
> please educate me.
>
> Second on the list was water in the fuel. Since I had just refueled
> (32.3 gallons) this was a viable source for engine roughness/stoppage. I
>
> had sumped the tanks but as we all know this may not be a thorough
> enough check. The fuel has since been checked again and again for water.
>
> Also no water was found in the carb bowl. Quality of the fuel has not
> been checked and could have been a bad batch.
>
> Since I seemed to think it was mixture related I thought it could be
> tied to the carburetor. I borrowed the new MA-4-5 from the new lycoming
> sitting in my shop and bolted it to the bottom of my engine. The damn
> thing pissed so much fuel from a stuck float or fod in the needle/seat
> that this was a bum test. Since it is not my carb I could not pull the
> bowl to check the condition. This carb is heading back to precision for
> warranty work. My carburetor has been cleaned, inspected and reassemble
> with new gaskets and needle/seat. Nothing out of the ordinary was found.
>
> I now have a nice shiny clean carburetor to install.
>
> Now for the major things I have checked.
>
> The carb as outlined above.
>
> Valve wobble. I had originally checked this in a rather crude method
> that I will not divulge here. I went ahead and purchased a wobble check
> fixture and checked wobble this past weekend. Wobble is in the range of
> .010 - .013 for the 4 cylinders. The acceptable range is .010 - .030
>
> Differential compression. Done on a cold engine and was (1)77/80
> (3)77/80 (2)76/80 (4)77/80.
>
> Spark plugs. Left mag is a slick impulse-coupled firing aviation plugs
> on the tops of 1 and 3 and the bottoms on 2 and 3. The right is a
> Electro-air running automotive plugs on the bottom of 1 and 3 and the
> tops on 2 and 4. Both ignition systems ran ran the same (rough) during
> the last episode. All plugs looked normal except for the bottom aviation
>
> plug on number 2 cylinder. The center electrode was leaning towards one
> side. A normal plug after running has a football shaped center electrode
>
> and looks like this (0) when viewed for gapping. Now imagine the center
> electrode leaning upwards almost closing the gap on the outside
> electrodes. My thoughts were excessive heat. Detonation?
>
> Cylinders/pistions. All look normal except for #2. It looks as if the
> carbon on the top of the piston has been blasted off, or changed color
> to a light tan. Again my thoughts lean towards excessive heat. I'm still
>
> looking for a borescope to borrow beg or steal.
>
> Mag timing. checked and is ok. One suggestion was that the EI on the
> right may be advancing the spark to maximum due to a failed/failing MAP
> sensor. This could cause preignition leading towards detonation. The MAP
>
> sensor has not been checked but is on my list of things to check.
>
> Baffles. I found a small chunk (1.0 x 0.5") missing in the right bottom
> corner of the left inlet ramp (due to cracking) This is the inlet in
> front of #2. I also have a plenum and the baffling material around the
> inlet on this side was split along the top. Since I have never liked the
>
> aluminum plenum top I have removed the plenum and replace with
> standard baffle/cowl seals and fixed all irregularities in the baffles
> including replacing the inlet ramp on number 2 cylinder. The top cowl is
>
> at home getting the top inlet ramp smoothing thingies glassed in.
>
> Conclusion: I have gone over the major items looked at and skipped the
> many little items. While valve sticking could be the culprit the valves
> pass the wobble check as per Lycomings specifications. While they fall
> in the low end of the specified limits for valve wobble they are within
> limits. #2 cylinder bothers me because of the funny looking spark plug
> and the clean looking piston. Hotspots formed by cracked and leaking
> baffles could have caused preignition/detenation in cyl 2. See
> http://www.avweb.com/news/columns/182132-1.html for more information on
> detonation.
>
> Part of me wants to pull the cylinders and take a good look inside.
> Would it be a waste of money? Not if it gives me good piece of mind
> while flying over the Rockies. I'm also thinking about installing a JPI
> EDM-700 or Insights GEM 610 so I can monitor all cht/egt with recording
> functions. This may be too much information most of the time but when
> engine problems arise I can see how it can be a great diagnostic tool.
> I'm also an aggressive leaner. Since my wife bought me a Fuel flow
> computer I have a tendency to lean, lean, lean trying to get the fuel
> flow down. I'm thinking this is not a good thing.
>
> Items that have been checked:
> Water or improper fuel
> Ignition timing
> Carburator
> Fuel flow and pressure
> valve wobble check
> restrictions in the intake system
> diff compression check
> Replaced plugs with clean refurbished plugs
> ignition leads (with a lead tester)
>
> Things that have been changed:
> plugs
> carburator
> major mods to baffling
>
> Things left to check:
> EI MAP sensor
> intake tube rubber hoses
>
> and anything else I can think of.
>
> Gary
__________________________________
Do you Yahoo!?
Yahoo! Mail - You care about security. So do we.
http://promotions.yahoo.com/new_mail
------------------------ Yahoo! Groups Sponsor --------------------~-->
Make a clean sweep of pop-up ads. Yahoo! Companion Toolbar.
Now with Pop-Up Blocker. Get it for free!
http://us.click.yahoo.com/L5YrjA/eSIIAA/yQLSAA/1yWplB/TM
--------------------------------------------------------------------~->
Online help on this group at:
http://help.yahoo.com/help/groups/
Yahoo! Groups Links
<*> To visit your group on the web, go to:
http://groups.yahoo.com/group/vansairforce/
<*> To unsubscribe from this group, send an email to:
vansairforce-unsubscribe@yahoogroups.com
<*> Your use of Yahoo! Groups is subject to:
http://docs.yahoo.com/info/terms/