Strange engine event

It's a fouled plug, burned valve or broken ring.

Fouled plug, maybe as it could clean itself up, a burned valve or broken ring
wouldn't fix themselves.

It's a fouled plug, burned valve or broken ring.

Fouled plug, maybe as it could clean itself up, a burned valve or broken ring
wouldn't fix themselves.

I certainly doubt something like a broken ring as well since the
problem has not yet re-appeared.

As far as the fouled plug theory - could a plug really get fouled
that quickly? Remember the plot looked like a sharp step function.
Most of the EGT/CHT change occurred in the first 20 seconds of the event.

So for now I think the injector theory, or the stuck valve or lifter
theory is more likely.

By the way I flew again yesterday for 2.5 hours and the problem
still has not repeated. So it may be awhile (if ever) before we
figure out the real cause.

~Paul

Hi Paul

The original reply that I gave you was for one cylinder.
Rereading your post, it seems that the readout was for all cylinders,
which changes the cause to Timing out or bad magneto.
(And no, I'm no expert on this stuff - I'm giving you these answers
right out of the book for my own engine analyzer).

HTH

--

Tony Roberts
PP-ASEL
VFR OTT
Night
Almost Instrument
Cessna 172H C-GICE


In article nospam-1C6AA9.22284826062004@shawnews,
tony roberts wrote:

It's a fouled plug, burned valve or broken ring.
And that is straight fom the book on my engine analyzer

Tony
C-GICE


In article ,
"Paul Mennen" wrote:

For the last 200 hours I've recorded all the data from my engine
analyzer which makes it easy to look at such things. Anyway a week
ago I was flying along steady at 12 thousand feet when I noticed
an unusual shift in the engine bar graph display. Looking at the
recorded data I see that all flight data is rock steady and all
engine data (and fuel flow) is also rock steady except for EGT1
and CHT1. From the beginning of the event this is what it looked
like:

Time after event EGT1 CHT1
---------------- --------- ---------
t = 0 1355F 300F
t + 20 seconds 77F rise 7F drop
t + 80 seconds 100F rise 19F drop
t + 3 minutes 114F rise 25F drop

After that it was pretty much steady, but I reduced power after
a few more minutes. (By the way, this is a Turbonormalized IO550.)
So EGT1 which was the coolest (as usual), rose to the level of the
warmest few cylinders. And CHT1 was the coolest (as usual) and
dropped away even more below the average. Still the final temps do
not seem that alarming, but when you look at the graph it looks
really strange since I've never seen such step changes unless it
was in response to some control input.

In the few flights I have taken since that event, I haven't seen
anything unusual like this happen again.

So to those of you who understand internal combustion engines -
what can cause a sudden drop in power in one cylinder like this?
Could something have fallen into this cylinder or could a
valve stick for a while or something? Or is this a sign that
something is breaking? What would you do about it? -
- Keep a close eye on it?
- Do an oil analysis?
- Ground it?
- Have a mechanic look at it?

Can a bad mag or spark plug cause such a thing? (BTW the engine
is a factory remain with 300 hours on it).

Thanks in advance for any insights you may have.
~Paul

I thought the values were only for cylinder #1 - hence the EGT1 and CHT1
headings.

--
Jim Carter
"tony roberts" wrote in message
news:nospam-978501.00081830062004@shawnews...
Hi Paul

The original reply that I gave you was for one cylinder.
Rereading your post, it seems that the readout was for all cylinders,
which changes the cause to Timing out or bad magneto.
(And no, I'm no expert on this stuff - I'm giving you these answers
right out of the book for my own engine analyzer).

HTH

--

Tony Roberts
PP-ASEL
VFR OTT
Night
Almost Instrument
Cessna 172H C-GICE


In article nospam-1C6AA9.22284826062004@shawnews,
tony roberts wrote:

It's a fouled plug, burned valve or broken ring.
And that is straight fom the book on my engine analyzer

Tony
C-GICE


In article ,
"Paul Mennen" wrote:

For the last 200 hours I've recorded all the data from my engine
analyzer which makes it easy to look at such things. Anyway a week
ago I was flying along steady at 12 thousand feet when I noticed
an unusual shift in the engine bar graph display. Looking at the
recorded data I see that all flight data is rock steady and all
engine data (and fuel flow) is also rock steady except for EGT1
and CHT1. From the beginning of the event this is what it looked
like:

Time after event EGT1 CHT1
---------------- --------- ---------
t = 0 1355F 300F
t + 20 seconds 77F rise 7F drop
t + 80 seconds 100F rise 19F drop
t + 3 minutes 114F rise 25F drop

After that it was pretty much steady, but I reduced power after
a few more minutes. (By the way, this is a Turbonormalized IO550.)
So EGT1 which was the coolest (as usual), rose to the level of the
warmest few cylinders. And CHT1 was the coolest (as usual) and
dropped away even more below the average. Still the final temps do
not seem that alarming, but when you look at the graph it looks
really strange since I've never seen such step changes unless it
was in response to some control input.

In the few flights I have taken since that event, I haven't seen
anything unusual like this happen again.

So to those of you who understand internal combustion engines -
what can cause a sudden drop in power in one cylinder like this?
Could something have fallen into this cylinder or could a
valve stick for a while or something? Or is this a sign that
something is breaking? What would you do about it? -
- Keep a close eye on it?
- Do an oil analysis?
- Ground it?
- Have a mechanic look at it?

Can a bad mag or spark plug cause such a thing? (BTW the engine
is a factory remain with 300 hours on it).

Thanks in advance for any insights you may have.
~Paul

On re-reading it, you are correct.
Oh well - I already answered that one

Tony



I thought the values were only for cylinder #1 - hence the EGT1 and CHT1
headings.

--
Jim Carter
"tony roberts" wrote in message
news:nospam-978501.00081830062004@shawnews...
Hi Paul

The original reply that I gave you was for one cylinder.
Rereading your post, it seems that the readout was for all cylinders,
which changes the cause to Timing out or bad magneto.
(And no, I'm no expert on this stuff - I'm giving you these answers
right out of the book for my own engine analyzer).

HTH

--

Tony Roberts
PP-ASEL
VFR OTT
Night
Almost Instrument
Cessna 172H C-GICE


In article nospam-1C6AA9.22284826062004@shawnews,
tony roberts wrote:

It's a fouled plug, burned valve or broken ring.
And that is straight fom the book on my engine analyzer

Tony
C-GICE


In article ,
"Paul Mennen" wrote:

For the last 200 hours I've recorded all the data from my engine
analyzer which makes it easy to look at such things. Anyway a week
ago I was flying along steady at 12 thousand feet when I noticed
an unusual shift in the engine bar graph display. Looking at the
recorded data I see that all flight data is rock steady and all
engine data (and fuel flow) is also rock steady except for EGT1
and CHT1. From the beginning of the event this is what it looked
like:

Time after event EGT1 CHT1
---------------- --------- ---------
t = 0 1355F 300F
t + 20 seconds 77F rise 7F drop
t + 80 seconds 100F rise 19F drop
t + 3 minutes 114F rise 25F drop

After that it was pretty much steady, but I reduced power after
a few more minutes. (By the way, this is a Turbonormalized IO550.)
So EGT1 which was the coolest (as usual), rose to the level of the
warmest few cylinders. And CHT1 was the coolest (as usual) and
dropped away even more below the average. Still the final temps do
not seem that alarming, but when you look at the graph it looks
really strange since I've never seen such step changes unless it
was in response to some control input.

In the few flights I have taken since that event, I haven't seen
anything unusual like this happen again.

So to those of you who understand internal combustion engines -
what can cause a sudden drop in power in one cylinder like this?
Could something have fallen into this cylinder or could a
valve stick for a while or something? Or is this a sign that
something is breaking? What would you do about it? -
- Keep a close eye on it?
- Do an oil analysis?
- Ground it?
- Have a mechanic look at it?

Can a bad mag or spark plug cause such a thing? (BTW the engine
is a factory remain with 300 hours on it).

Thanks in advance for any insights you may have.
~Paul







--

Tony Roberts
PP-ASEL
VFR OTT
Night
Almost Instrument
Cessna 172H C-GICE