CHT temps

[Wingover]

I’m seeing a strange CHT pattern on my new to me (and new engine) Mooney M20J 205.  The #1 is hotter than the rest and especially #4.  Pictures was taken at 8500 pressure altitude.  I notice that I have to keep the cowling flap a little open to keep the temp below 380f if fully closed I see 385-388 on #1

New silicon baffle seals.

[Fritz1]

Swap temp sensors from hottest to coldest and clean blade contacts on sensor leads

[N201MKTurbo]

Doesn’t look bad to me.

[N201MKTurbo]

You have no baffle seals on the front of your baffles.

[Ragsf15e]

I agree with @N201MKTurbo, doesn’t look bad, but im also curious about your power setting… 9.6gph at 8500’ and those egts make me think you’re right at peak egt or maybe barely rich side which is going to be a hot cht setup.  Couple that with 5c oat at 8500’ and it might be pilot induced.  
 

I would try 100 rich of peak or 9.0gph at same altitude. Either way, I bet your chts will be a little lower and you can close your cowl flaps.

@Wingover

Edited March 15 by Ragsf15e

[EricJ]

The age of the baffle seals isn't as important as how well they're actually sealing against the cowl.    With the cowl on, put a light source (flashlight, whatever) behind them through the oil hatch and look in the front air inlets.    You'll be able to see wether they're sitting against the cowl or folding up and leaving big gaps.

Also, +1 that in the pic there's no seals on the bottom front of your baffles.   That's an important area as the pressure is very high there since it is near the inlets.   If the air is going out around that it'll defeat a lot of the flow around the cylinders.

It's also good to check the condition of the metal parts of the baffles, as they can grow holes and gaps that let a lot of air through.

[Jim F]

As  @N201MKTurbo & EricJ its about the how the seals - seal.  Think about every space that air can leak as a problem that must be fixed.  The only way to cool the cylinder is to have air flow down through the cylinder fins.  1) You are missing all the lower front cowl seals.  2) Cyl #1 looks like you only have a front and back pop rivets and you are missing the pop rivets in the middle.  3) The prop gov hard line in missing a grommet.  4) the back seal is vertical, you normally would like to see a bend forward so when the upper cowl is put on the seal faces forward and the high pressure above the engine pushes the seal on the cowl.  If any seal folds over toward the low pressure area you will lose a huge amount of cooling air.  When you put on the lower cowl on make sure all the lower seals are in the correct direction, think high pressure low pressure.  When you put on the top cowl look in with a flash light and make sure all seals face the correct direction, forward and inboard.  

 

[Wingover]

57 minutes ago, N201MKTurbo said:

You have no baffle seals on the front of your baffles.

The picture was taken as they were putting them on.  Here it is

[Wingover]

1 hour ago, Fritz1 said:

Swap temp sensors from hottest to coldest and clean blade contacts on sensor leads

They are new sensors but will take a look 

[kortopates]

They are new sensors but will take a look 

But it’s an EDM-830 correct? Given that one of the sensors is non-standard because of your OEM cht probe is already installed in one of the cylinders. Find out which cyl that is and the type of probe, so that you know what you’re comparing with.


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[Wingover]

24 minutes ago, Jim F said:

As  @N201MKTurbo & EricJ its about the how the seals - seal.  Think about every space that air can leak as a problem that must be fixed.  The only way to cool the cylinder is to have air flow down through the cylinder fins.  1) You are missing all the lower front cowl seals.  2) Cyl #1 looks like you only have a front and back pop rivets and you are missing the pop rivets in the middle.  3) The prop gov hard line in missing a grommet.  4) the back seal is vertical, you normally would like to see a bend forward so when the upper cowl is put on the seal faces forward and the high pressure above the engine pushes the seal on the cowl.  If any seal folds over toward the low pressure area you will lose a huge amount of cooling air.  When you put on the lower cowl on make sure all the lower seals are in the correct direction, think high pressure low pressure.  When you put on the top cowl look in with a flash light and make sure all seals face the correct direction, forward and inboard.  

 

Would you be able to mark on the photo the governor grommet location yiu mention and explain better what do you mean buy “middle pop rivets “?

[Wingover]

5 minutes ago, kortopates said:

But it’s an EDM-830 correct? Given that one of the sensors is non-standard because of your OEM cht probe is already installed in one of the cylinders. Find out which cyl that is and the type of probe, so that you know what you’re comparing with.


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I didn’t realize that you use an existing prob. I thought when they install the EDM it comes with 4 probs.  The plane had the EDM installed when I bought it.

[Shadrach]

8 minutes ago, Wingover said:

The picture was taken as they were putting them on.  Here it is

Are you sure the rear baffle seal was dressed forward so that it sealed against the cowl under pressure? It looks like it could easily be faced the wrong way.  I learned early on in my ownership experience that if the rear seal is folded back rather than forward, cooling capacity is diminished a great deal. 

[Ragsf15e]

6 minutes ago, Wingover said:

I didn’t realize that you use an existing prob. I thought when they install the EDM it comes with 4 probs.  The plane had the EDM installed when I bought it.

If it’s an 830, it’s not considered a primary instrument. To install it, they had to leave the sensor on one of your cylinders for the original gauge. That sensor may have a piggyback sensor feeding the 830 which will not read exactly correct. Find out which cylinder has the different sensor on it.

[Wingover]

2 minutes ago, Shadrach said:

Are you sure the rear baffle seal was dressed forward so that it sealed against the cowl under pressure? It looks like it could easily be faced the wrong way.  I learned early on in my ownership experience that if the rear seal is folded back rather than forward, cooling capacity is diminished a great deal. 

Yes, I looked inside the cowling and it points forward 

[jaylw314]

2 hours ago, Wingover said:

They are new sensors but will take a look 

If they are new sensors, that increases the probability that they are incorrectly installed or in the wrong order.  Double check your FF calibration constant as well.

Otherwise, the temps don't look bad.  

[redbaron1982]

5 hours ago, Wingover said:

I’m seeing a strange CHT pattern on my new to me (and new engine) Mooney M20J 205.  The #1 is hotter than the rest and especially #4.  Pictures was taken at 8500 pressure altitude.  I notice that I have to keep the cowling flap a little open to keep the temp below 380f if fully closed I see 385-388 on #1

New silicon baffle seals.

My two cents: I was troubleshooting a hight cht on #3 when someone here at MS pointed out that I was missing a baffle in front of my #1 cyl. It's a small L shaped aluminum plate, that you have in you engine, right in front of #1. 

I installed this baffle and #3 temp went down but #1 went way higher. I finally decided to remove it and leave it as it was before. 

I don't know if it is better to leave it on or not,.from my experience it seems better to leave it off. 

[Gee Bee Aeroproducts]

Poor design 

too thick material 

.093 is spec

Too Tall / Wide 

They should be pulled tight on the rear for a forward angle bend

Typical homemade seals

incorrect design is just as bad as no seals 

The cowl should just drop on 

Next you will be trying to make a valve cover gasket

 

[kortopates]

On 3/15/2024 at 2:04 PM, Wingover said:

I didn’t realize that you use an existing prob. I thought when they install the EDM it comes with 4 probs.  The plane had the EDM installed when I bought it.

Of course it comes with 4 probes since you have 4 columns of CHT on your EDM-830. But EDM-830 are not certified for primary instrumentation meaning you have to retain your factory OEM CHT probe which is installed into one of the cylinder wells. Since you can't install 2 standard probes into the same cylinder well an EDM-830 installation will have 1 non-standard probe installed on the cylinder that already has the factory OEM CHT probe in the cyl well. All 3 options for the non-standard probes do not indicate the same as a probe in the cylinder well so that 4th probe can indicate higher or lower than actual depending on the probe. So getting back to the point, In order to properly interpret and compare your CHTs, with a non-primary installation like an EDM-830, you need to know what non-standard probe is being used in which cylinder.  

Edited March 18 by kortopates

[Jim F]

6 hours ago, Wingover said:

Would you be able to mark on the photo the governor grommet location yiu mention and explain better what do you mean buy “middle pop rivets “?

There should be a rubber grommet in the area in red, one to seal the air gap and two to keep from chaffing through the line.  jim

[Jim F]

The red oval shows the missing rivets

[Wingover]

4 hours ago, Jim F said:

There should be a rubber grommet in the area in red, one to seal the air gap and two to keep from chaffing through the line.  jim

Thank you Jim !!

[Wingover]

4 hours ago, Jim F said:

The red oval shows the missing rivets

They are actually there.  The picture was taken just as they were installing everything.

[Shadrach]

2 hours ago, Wingover said:

They are actually there.  The picture was taken just as they were installing everything.

Even if it were missing, that would not cause your CHT issue.

[Wingover]

1 hour ago, Shadrach said:

Even if it were missing, that would not cause your CHT issue.

Yes, but Jim was right to point out just as FYI so it can be fixed (if it was actually left that way)