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High CHT, 470 degrees +.


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1 hour ago, Andy95W said:

Looks good, Brice, but it looks like you might be missing the inter-cylinder baffling between your #2 and #4 cylinders.  It's difficult to tell based on your photo looking down.

The photo below shows a different Lycoming engine, from underneath the cylinder.  The O-360 baffle is smaller.

IMG_2349.JPG
 

EDIT- this is the parts manual for the O-360.  Ours are quite a bit smaller.

96F3A6D7-03B8-4CA5-AD9B-57151CB83598.png

It's there. You can see it in this picture

20200407_122048.jpg

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22 minutes ago, Andy95W said:

Well, dang.  Wish I could’ve been more help.

I know, right! 

It's so frustrating.  I've seen some dog houses in BAD shape and they're getting acceptable temps.  Mine is probably better than average, anything that needs fixing on it would bring temps down a couple degrees, but not 100+.  

 

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I think you have a minor exhaust leak, maybe two.  Three circles.  First the small cooling fin looks reddish, second shows some light streaking on the larger fin and the third circle might be of some blow from the EGT clamp, on the fin , behind the plug wire.  Don’t know that it alone would cause the high temp, but may contribute.

87882012-5421-464F-8DA4-A1245D2B745E.jpeg

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5 minutes ago, takair said:

I think you have a minor exhaust leak, maybe two.  Three circles.  First the small cooling fin looks reddish, second shows some light streaking on the larger fin and the third circle might be of some blow from the EGT clamp, on the fin , behind the plug wire.  Don’t know that it alone would cause the high temp, but may contribute.

87882012-5421-464F-8DA4-A1245D2B745E.jpeg

I'll try the shop vac trick. Pressurize the exhaust and spray soapy water. 

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Here's today's flight.  https://apps.savvyaviation.com/flights/3850525/2553d6d9-4e1d-48ad-99e7-2b9eefde89f4

Pre takeoff mag checks start at 8 minutes.  Takeoff is at 11:30.

I climbed to 8500'.  Took a while at low MAP to keep the cylinder cool. 

I leaned as much as I could with still running smooth.  Ignition stress test at 31 minutes.  Bendix mag first. Then let stabilize and the second peak is the surefly starting at 33 minutes.

Next was the gami spread.  I started leaning about 37:30.

#3 peak 1432 at 9.3gph: 221df spread

#1 peak 1384 at 8.7gph: 273df spread

#4 peak 1399 at 8.4gph: 299df spread

#2 peak 1404 at 8gph: 327df spread

Last is the induction leak test.

High MP

#1-1177 #2-1124 #3-1274 #4-1163

Low MP

#1-1172 #2-1168 #3-1199 #4-1176

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23 hours ago, ragedracer1977 said:

I'm guessing it's time to call in a big gun.

Yes, it is time. Whatever they charge it will be less than the cylinder that you will need to replace if you do not correct this.

All you will get here is speculation.

I suggest Maxwell, but others exist that can fix this if he is inconvenient.

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5 minutes ago, HRM said:

Yes, it is time. Whatever they charge it will be less than the cylinder that you will need to replace if you do not correct this.

All you will get here is speculation.

I suggest Maxwell, but others exist that can fix this if he is inconvenient.

All that we can do is speculate as most of us volunteer our time and knowledge and don’t make house calls.  Please point me to one post here where Don offered any help or advice.

Clarence

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Just now, M20Doc said:

All that we can do is speculate as most of us volunteer our time and knowledge and don’t make house calls.  Please point me to one post here where Don offered any help or advice.

Clarence

Don keeps a low profile. Frankly, I think this has to be looked at 'in vivo' and he is not the only one who could solve this.

Speculation is only a bad thing in legal matters, as the OP stated, he is building a case to put before the big gun.

I just think it is time for the "big gun'. To look, to analyze and to solve.

I've been wrong, we'll see, won't we?

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12 minutes ago, HRM said:

Yes, it is time. Whatever they charge it will be less than the cylinder that you will need to replace if you do not correct this.

All you will get here is speculation.

I suggest Maxwell, but others exist that can fix this if he is inconvenient.

I agree.  Id consider taking it to Maxwell, but that's a 5 hour flight.  And in the current situation, I'm not sure I want to ride the germ tube back home

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It is good to see some things behaving very repeatably... (Brice’s O360... :))

Have you ever cleaned the intake out of an engine before... any engine?

I learned to do this with my Chevy...  lots of exhaust gumming up the works in the intake...

When I went to apply the same theory to my O360... I was incredibly surprised by what I found... (no exhaust, something worse)

There can be a very thick coating of blue goo growing inside the intake tubes, and all the way up into the area where the fuel enters the intake valve...

After the carburetor, the fuel air mixture travels through the intake tubes heated by the oil in the oil pan...

Lots of evaporation going on depositing lots of blue die and lead compounds.... the build up is thick gooey and is better off not being in there...

 

If going to the big gun... or paying Savvy to review your data... that last flight with the details of each step over time... will be very helpful...


The first oddity I see... occurs when the prop control is pulled back... the four EGTs spread out... what causes that?

The engine starts breathing differently with EGT1 notably running cold... the red colored line...

When the throttle is pushed in for T/O it is expected that all four EGTs will rise in unison...

EGT1 fails to get off the ground.... EGT2 is close behind...

Near 12:30... EGT1 and EGT2 start to climb... as if they just joined the T/O party...   what is causing this behavior?

It looks like Cylinder #4 is doing notably more work than the others... or it is just closer to peak than the others...

Any vibration with that?

How old is the carb?
Has it been OH’d?

Has it been serviced in any way?

Has it been cleaned out?

 

From the wacky 1.3 Gami spread...  compare that to other Savvy O360s /M20C&Ds.... see what the norm is...

from the wacky EGT1 falling out during the prop pull... flying the plane isn’t required to see the oddities...

Looks like EGT1 is running extra rich 100°F... could be as simple as EGT1 sensor location?

What caused EGT1&2 to delay warming up during T/O?  This won’t be sensor location.  Looks as if something is changing there...

The inflight mag test is really interesting...

It appears that the Surefly... is operating so strongly it is burning more fuel than an ordinary single mag... :)

 

Eeeeesh... what happens at  34:30? is this when the Surefly takes a Classic break?   Going between one mag and the other...?

There is a bit of a lag that occurs switching between mags and the electronic mag’s computer has a start-up moment... documented in several places...

Helps to have the two independent on/off mag switches for this effect... the rotary ignition switch causes extra challenges going through the single mag locations...

I get baffled again with the Gami spread... a new and different cylinder stands out as the hot one... EGT3 stays warmer than the others while you are doing the test...

See what it costs to have savvy review your data...

See what it cost to rinse the intake out... some of the tubes are easy to remove and clean... the valve covers are easy to remove and you will see where air/fuel goes.... lots of blue goo... there too...

If you see tons of blue glue that has deposited over decades... get it cleaned out and collect the same data again...see if things improve...

If the carb hasn’t been OH’d in decades and thousands of hours... this could be interesting as well...

Sometime the wrong fuel jet gets used for various reasons... it is possible to see improvements with a new or different jet...

I wish my O360 had a JPI.... 

Lastly... during shut down... do you lean slowly to see an rpm rise?  I don’t see it in the data... this is a simple test to see if something in the mixture is set up properly... the rpm should rise as it goes from deep ROP to LOP to deep LOP to unable to run...

PP ideas only, not a mechanic...

Best regards,

-a-

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Alot to reply to there lol.

Intake gaskets and rubber "slip joints" were  replaced not long ago.  Tubes were clean.

Carb has not been touched in over 1000 hours. I would have to pull the logbook to be certain.

How would I compare it to other o360 data?

I looked at the mag test, fuel burn looks essentially the same no matter which mag.  What are you seeing?

34:30 was a "marker".  I pulled the throttle way back to mark when I was getting ready to start a test. There are 3 "marks" like that.

I enrolled in savvy analysis and requested a review.  

On shut down, I didn't lean slowly.  I saw a rise of about 30 some odd RPM with a relatively quick pull.  However, I really am starting to lean towards a fuel issue. 

 

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Savvy does the comparing for you...

Part of their service...

They can review your plane through time...  and across similar planes at the same time...

You may find this is the best that O360s can get...

Climbing out @120mph is usually done to keep CHTs cooler than their redline...

Having a JPI just opened Pandora’s box of engine details... :)

It will be really interesting to see if other O360s behave similarly... Dev has a JPI on his M20C... but he hasn’t been around for a couple of weeks with the Covid activities increasing in the area...

Paul Kortopates is our connection to Savvy... he may be able to find Dev’s data if he left it shareable...

Best regards,

-a-

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5 minutes ago, carusoam said:

Savvy does the comparing for you...

Part of their service...

They can review your plane through time...  and across similar planes at the same time...

You may find this is the best that O360s can get...

Climbing out @120mph is usually done to keep CHTs cooler than their redline...

Having a JPI just opened Pandora’s box of engine details... :)

It will be really interesting to see if other O360s behave similarly... Dev has a JPI on his M20C... but he hasn’t been around for a couple of weeks with the Covid activities increasing in the area...

Paul Kortopates is our connection to Savvy... he may be able to find Dev’s data if he left it shareable...

Best regards,

-a-

I don't think climbing out at 125mph, 23" map, and 2-300 fpm to keep a cylinder under 500F is the best an O360 can get.

I had a quality engine monitor before, I used to be able to climb out like a normal person without going over 410.  Part of the reason I installed this JPI was to start problem solving why #4 just keeps getting hotter and hotter.  This behavior has been developing since late last year, but it's getting worse, not better

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Sorry Brice but I didn’t have time to read every post. Forgive me what I’m about to say has been covered.

Possible problems already ruled out:

 Intake leak 

 Exhaust leak 

Mag timing incorrect

Leaking baffle seal

So looking at your original post you have three cylinders behaving normally and one cylinder with an excessively high CHT in a low EGT.

This tells us that there is less energy being expulsed from the hot cylinder in the exhaust stroke. This makes sense as it’s clear that that energy is being transferred to the cylinder. Indeed more energy is being transferred to the cylinder than the design is able to dissipate. The question is why. I would submit that the combustion event is either happening too fast, happening too early or both. A lean mixture could cause this, but so could mild pre-ignition. Have either of the cylinder’s plug holes ever been helicoiled?  

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Ross,

This is your kind of challenge...

Something has changed over time... causing CHT4 to misbehave...

I made a dozen observations... but nothing sticks out as THE cause...

One detail to keep in mind... a Surefly mag is being used...
 

Looking forward to your insight... :)

Best regards,

-a-

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8 minutes ago, ragedracer1977 said:

I don't think climbing out at 125mph, 23" map, and 2-300 fpm to keep a cylinder under 500F is the best an O360 can get.

I had a quality engine monitor before, I used to be able to climb out like a normal person without going over 410.  Part of the reason I installed this JPI was to start problem solving why #4 just keeps getting hotter and hotter.  This behavior has been developing since late last year, but it's getting worse, not better

I wouldn't fly it until you figure this out.  I read in Mike Buschs' Engines that at about 500F is where so much of the strength of aluminum is lost that cyl. heads start to think about popping off the cylinder.  

Just a PPSEL, not an A&P.

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11 minutes ago, Shadrach said:

Sorry Brice but I didn’t have time to read every post. Forgive me what I’m about to say has been covered.

Possible problems already ruled out:

 Intake leak 

 Exhaust leak 

Mag timing incorrect

Leaking baffle seal

So looking at your original post you have three cylinders behaving normally and one cylinder with an excessively high CHT in a low EGT.

This tells us that there is less energy being expulsed from the hot cylinder in the exhaust stroke. This makes sense as it’s clear that that energy is being transferred to the cylinder. Indeed more energy is being transferred to the cylinder than the design is able to dissipate. The question is why. I would submit that the combustion event is either happening too fast, happening too early or both. A lean mixture could cause this, but so could mild pre-ignition. Have either of the cylinder’s plug holes ever been helicoiled?  

To be fair, it looks like at least 3 cylinders are getting hot.  2 and 3 were on their way to well over 430 when I pulled the power back.  It's just #4 is really really hot.

As far as I know, the cylinders have not been helicoiled.  They are at 7-750 hours I beleive, and I've put 90% of those hours on them. 

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How deep ROP are you able to get during T/O power?

This should be near 300°F ROP...

Engine set-up usually takes care of this...

Check mixture cable to see if anything is coming apart at either end... thinking of changes over time...

leaning to kill the engine... there should be an rpm rise prior to it dying... another mixture related set-up thing...

Best regards,

-a-

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Just now, carusoam said:

How deep ROP are you able to get during T/O power?

This should be near 300°F ROP...

Engine set-up usually takes care of this...

Check mixture cable to see if anything is coming apart at either end... thinking of changes over time...

leaning to kill the engine... there should be an rpm rise prior to it dying... another mixture related set-up thing...

Best regards,

-a-

Looking at the GAMI spread test (full rich to peak EGT) 220-300 degrees depending on the cylinder. 

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If CHT4 is the one that is only getting 220 ROP...

That would be interesting...

With the IO550... we lean in a range from 300° to 200°F... during the climb... (blue box EGT method)

If you leave the mixture in during the climb... the MP drops faster than the FF... EGTs are getting colder as you go higher...

When we drop out the bottom of the blue box, adjust the mixture to the top of the box again...

Best regards,

-a-

 

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