#3 Cylinder runs very hot after overhaul

[kmyfm20s]

Maybe @kortopates can take a look at the above screen shot of your data. I know you said they tested for an induction leak but that’s what it looks like It is to me. 

[HRM]

1 hour ago, kmyfm20s said:

Maybe @kortopates can take a look at the above screen shot of your data. I know you said they tested for an induction leak but that’s what it looks like It is to me. 

Same here. I was in the baffling camp, and this is still somewhat baffling, but looking like induction now. 

[Greg Ellis]

Paul did analyze this data through Savvy.  They pressurized the induction system and found no leaks anywhere.  But I will revisit that as well with them.  Thanks.

[HRM]

Just now, Greg Ellis said:

Paul did analyze this data through Savvy.  They pressurized the induction system and found no leaks anywhere.  But I will revisit that as well with them.  Thanks.

Isn't induction a negative (vacuum) as opposed to a positive pressure system? Is it possible, for example, that an induction stack seal might be fine under pressure, but leak under suction?

Just WAGS at this point.

[ArtVandelay]

Maybe [mention=7862]kortopates[/mention] can take a look at the above screen shot of your data. I know you said they tested for an induction leak but that’s what it looks like It is to me. 

If it was then shouldn’t we see the problem on the ground as well?
If the problem only occurs when the plane is moving then I would think the problem is with the baffling.

[kmyfm20s]

4 hours ago, ArtVandelay said:

If it was then shouldn’t we see the problem on the ground as well?
If the problem only occurs when the plane is moving then I would think the problem is with the baffling.

Higher manifold pressures will make induction leaks more pronounced. The EGT’s of 1 & 3 as well as the CHT’ of 1,2 & 4 come in line with each other once in cruise is I’m sure why Paul feels like it’s not a leak. We know EGT readings are relative but the #3 cylinder on 360 Lycoming engines is always a wildcard. My guess is #1 EGT just reads high since it parallels 2 & 4. Something is making the EGT of #3 rise disproportionately on takeoff and the CHT follows for that cylinder. 

[jaylw314]

3 minutes ago, kmyfm20s said:

Higher manifold pressures will make induction leaks more pronounced. The EGT’s of 1 & 3 as well as the CHT’ of 1,2 & 4 come in line with each other once in cruise is I’m sure why Paul feels like it’s not a leak. We know EGT readings are relative but the #3 cylinder on 360 Lycoming engines is always a wildcard. My guess is #1 EGT just reads high since it parallels 2 & 4. Something is making the EGT of #3 rise disproportionately on takeoff and the CHT follows for that cylinder. 

Don't you mean higher MP will make induction leaks LESS pronounced?  The higher the MP, the closer to ambient air pressure, so the leak becomes less of an issue.

[carusoam]

K has nailed the ‘issue’ with the graph he posted above...

The graph is a bit busy and may not be really obvious...

Around 8 minutes into the data collection... something happens... The throttle gets pushed in and things start to happen...

The brown EGT3 line Rises faster than the other three...

We know it’s most likely not a baffling issue, because the EGT rise is followed by a CHT rise... when the EGT is that hot CHT doesn’t have a choice but to follow along...

What did the pilot do at 8 minutes? (Pushed the throttle in to full FF)

What caused the fuel distribution to change..?

Does this happen repeatably? 
 

The oddity that adds to the repeatability challenge... looks like the pilot performs an inflight mag check... and the EGT3 is back in line with its neighbor...

 

Expect that there is something going on with a mag or a plug related to EGT3...

For some reason, start-up and mag check don’t seem to show the issue...

A good sloooow mag check will reveal a few things about each plug and mag timing variations... do a mag check and allow the EGTs to fully rise and level off... might take 15-20 seconds on each mag position...

This is a special mag check to verify or find what is/isn’t working... probably not an every day mag check...

Whatever it was seems to have cleared out after the inflight mag test...

See same graph, maybe a bit clearer...

I put a line at the 8minute mark and the data set comes with it...

Did Paul give you a homework assignment to go with that?

PP thoughts only, not a mechanic...

Best regards,

-a-

If there is a leak into the intake... a small leak has a bigger affect at low MP... at high MP, air might not even be drawn through the leak anymore.... it will be percentage wise small...

[kmyfm20s]

On 6/25/2020 at 9:14 AM, jaylw314 said:

Don't you mean higher MP will make induction leaks LESS pronounced?  The higher the MP, the closer to ambient air pressure, so the leak becomes less of an issue.

You are correct! I hate when I get things backwards:(

[Greg Ellis]

An update on my hot cylinder #3.  The mechanic working on this issue stuck with it.  He checked everything.  Baffling, timing, borescope, plugs, etc, etc....if you read my previous posts it gives you an idea of what we were going through.  I took all advice from the forum to him as well and nothing was making a difference.  JPI has been closed due to coronavirus.  But my mechanic was able to get a hold of the tech that he usually works with.

Turns out on some Lycoming cylinders there is an issue with the way the CHT probe fits in the cylinder.  I do not know the exact issue but it has something to do with spot for the probe being bored too deep and the probe does not sit in the right spot.  It has happened enough times that JPI has a fix for it.  They put in a special sleeve and a spacer.  Viola...the CHT on #3 was in line with the others and never went above 370 on take off.  It was going up to 470 before the fix.  I had emailed back and forth twice with JPI and told them my issue and they never once mentioned this.  They said to me that no way it could be the monitor or the probe.  Too bad.  Could have saved hours and hours of labor.

So while I do not know the specifics on what happened, I put this out there just in case anyone else has the same issue.  But I am very happy now.  Plane is running cool and it is happy as well.  Thanks to everyone who offered help with this.

[HRM]

4 minutes ago, Greg Ellis said:

Thanks to everyone who offered help with this.

Told you it was baffling 

Congrats and happy flying!

[carusoam]

Greg,

there is one common reason this same challenge shows up time after time...

1) We have four cylinders....

2) We have four cylinder TC wells...

3) Each well fits one TC...

4) We add a JPI that has four TCs, wanting four wells...

5) We have a Ship’s CHT gauge, with its own TC, resident in one of the wells... The FAA wants us to use this for protection of the engine’s CHT red line...

6) Imagine 5 TCs, four Wells...

7) Honorable mechanic looks up standard solution... finds a TC that fits under the spark plug in place of the plug gasket...

8) Great idea, only 50°F hotter, because of where it is measuring, not that the TC doesn’t work right...

9) JPI has come up with a similar, harder to mess up, piggy back TC that fits under the TC well hardware.... not perfect, still off by 25°F... Because it is measuring the area around, but not in the well...

10) Many MSers visually check to see what TC they have, where it is located, and try to remember this for a decade...

11) After a decade, I tend to forget what is located where... 
 

So... if anyone is going through the effort to find out why their baffling isn’t cooling evenly... make sure your engine monitor is measuring evenly first... then work on the seals and holes and....

JPI could sell thousands of dual TCs that fit in the same well and supply two independent CHT instruments....

We could name it The MSers Care TC.... 
 

An STC would probably be required to buy and use and install... The pilots would really like to have this solution... 

This would make a great project for @takair who has the skills to engineer aviation products, and write The proper STCs... (invite for Rob)

It would be better than a second well molded/drilled/threaded in the cylinder....

PP thoughts only, not a mechanic...
 

Best regards,

-a-

[kmyfm20s]

That good news! I wonder why the EGT runs so much higher on that cylinder?

[ragedracer1977]

10 hours ago, Greg Ellis said:

An update on my hot cylinder #3.  The mechanic working on this issue stuck with it.  He checked everything.  Baffling, timing, borescope, plugs, etc, etc....if you read my previous posts it gives you an idea of what we were going through.  I took all advice from the forum to him as well and nothing was making a difference.  JPI has been closed due to coronavirus.  But my mechanic was able to get a hold of the tech that he usually works with.

Turns out on some Lycoming cylinders there is an issue with the way the CHT probe fits in the cylinder.  I do not know the exact issue but it has something to do with spot for the probe being bored too deep and the probe does not sit in the right spot.  It has happened enough times that JPI has a fix for it.  They put in a special sleeve and a spacer.  Viola...the CHT on #3 was in line with the others and never went above 370 on take off.  It was going up to 470 before the fix.  I had emailed back and forth twice with JPI and told them my issue and they never once mentioned this.  They said to me that no way it could be the monitor or the probe.  Too bad.  Could have saved hours and hours of labor.

So while I do not know the specifics on what happened, I put this out there just in case anyone else has the same issue.  But I am very happy now.  Plane is running cool and it is happy as well.  Thanks to everyone who offered help with this.

I just forwarded this to the new owner of my C.  Nearly identical issue.  Did JPI provide the spacer and stuff?

[ragedracer1977]

10 hours ago, carusoam said:

Greg,

there is one common reason this same challenge shows up time after time...

1) We have four cylinders....

2) We have four cylinder TC wells...

3) Each well fits one TC...

4) We add a JPI that has four TCs, wanting four wells...

5) We have a Ship’s CHT gauge, with its own TC, resident in one of the wells... The FAA wants us to use this for protection of the engine’s CHT red line...

6) Imagine 5 TCs, four Wells...

7) Honorable mechanic looks up standard solution... finds a TC that fits under the spark plug in place of the plug gasket...

8) Great idea, only 50°F hotter, because of where it is measuring, not that the TC doesn’t work right...

9) JPI has come up with a similar, harder to mess up, piggy back TC that fits under the TC well hardware.... not perfect, still off by 25°F... Because it is measuring the area around, but not in the well...

10) Many MSers visually check to see what TC they have, where it is located, and try to remember this for a decade...

11) After a decade, I tend to forget what is located where... 
 

So... if anyone is going through the effort to find out why their baffling isn’t cooling evenly... make sure your engine monitor is measuring evenly first... then work on the seals and holes and....

JPI could sell thousands of dual TCs that fit in the same well and supply two independent CHT instruments....

We could name it The MSers Care TC.... 
 

An STC would probably be required to buy and use and install... The pilots would really like to have this solution... 

This would make a great project for @takair who has the skills to engineer aviation products, and write The proper STCs... (invite for Rob)

It would be better than a second well molded/drilled/threaded in the cylinder....

PP thoughts only, not a mechanic...
 

Best regards,

-a-

I'm guessing that's incorrect in this situation.  Primary monitor replaces the factory TC.  There is no piggyback

[Greg Ellis]

1 hour ago, ragedracer1977 said:

I just forwarded this to the new owner of my C.  Nearly identical issue.  Did JPI provide the spacer and stuff?

I am not exactly sure but I can find out for you.  Not sure if they are working on July 4th.  They usually work on Saturday but not sure about this Saturday. 

[Greg Ellis]

1 hour ago, ragedracer1977 said:

I'm guessing that's incorrect in this situation.  Primary monitor replaces the factory TC.  There is no piggyback

The EDM 900 did replace all of my other engine instruments as a primary.

[HRM]

10 hours ago, kmyfm20s said:

That good news! I wonder why the EGT runs so much higher on that cylinder?

Baffling!

[ragedracer1977]

10 hours ago, Greg Ellis said:

I am not exactly sure but I can find out for you.  Not sure if they are working on July 4th.  They usually work on Saturday but not sure about this Saturday. 

That would be great. I'd love to pass it on to the new owner. 

[chriscalandro]

I took my Dynon maiden flight after my annual yesterday and found my #3 has exactly the same symptoms described in this thread...

[salty]

On 7/3/2020 at 9:55 PM, kmyfm20s said:

That good news! I wonder why the EGT runs so much higher on that cylinder?

I have a similar situation. Your observation makes me think the spacer is masking the truth. 

[N201MKTurbo]

I have noticed that CHT varies considerably depending on where it is measured. The difference between the bottom of the thermowell, the middle of the thermowell, the mounting threads of the thermowell or a sparkplug gasket ring thermocouple. can vary by as much as 50 degrees. Yet everybody talks about the sacred CHT temperatures like there is only one true answer.

The old AN thermocouples were spring loaded against the bottom of the well. The Rochester sensor that came stock in my 201 is not spring loaded and goes about 3/4 into the well. Most of the aftermarket thermocouples are suspended in the middle of the well and only contact the well at the threads. These are all going to give different readings.

I've never tried it, but putting some Wakefield compound in the well would probably make them work better.

[mooniacX]

Do you have a part  # for the sleeve and spacer? Glad you found the fix!!

[o-360]

I am still perplexed?

Your posted engine monitor report showed the high EGTs on #3 tracked proportionality to the high CHTs? 

Jim 

[o-360]

Just to let everyone know...anyone with the O-360-A1D needs to verify their carb is either the 10-3878 stamped with an "M" or the 10-4164-1 carb.

I had high #3 and #4 CHTs for years and couldn't figure it out. Finally, I came across the Marvel Schweber service bulletin from 1962 for the Mooney M20B and M20C. It stated that the carb for these engines needed that modification kit to re-jet the carb which was a field A & P mod...and then the carb was stamped with an "M". the 10-3878 carb will NOT put out enough FF for this engine.

Researching further, I discovered the upgraded carb for this engine was the 10-4164-1 which puts out almost 18 GPH on takeoff. I had checked timing, baffling, adjusted climb out procedures, etc...all in vein. My #3 and #4 CHTs would quickly climb to 440+ before I even reached 2000 feet.

I installed this 10-4164 carb and problem was solved!!! I did my first max climb to 2000 feet, 1100 FPM, full throttle, with airspeed all the way down to 70 kts. CHTs never went higher then 390! It was like night and day.

I also had previous problems with the 10-3878 carb like engine knocking in cruise (similar to a fowled plug). Turned out it was pre-detonation from the engine running WAY to lean. 

BTW...I have a Cherokee 180 with engine & CSP mod (O-360-A1D).

Jim