EGT question

[Alan Maurer]

Hello Mooney People

Top overhaul has gone well. CHT's look good and stable. Noted that #4 EGT was running about 100 degrees higher than the others. Switched #4 EGT probe with #6

EGT now on #6 looks fine but #4 is still hot. So...question....Other than a bad probe , what will cause a higher temperature  display in #4 EGT other than the probe? Could it still be part of the break  in since it is a new cylinder with about 17 hours since work done?  

Thanks,

Alan

Ovation IO550

[Deb]

18 minutes ago, Alan Maurer said:

Top overhaul has gone well. CHT's look good and stable. Noted that #4 EGT was running about 100 degrees higher than the others. Switched #4 EGT probe with #6

EGT now on #6 looks fine but #4 is still hot. So...question....Other than a bad probe , what will cause a higher temperature  display in #4 EGT other than the probe? Could it still be part of the break  in since it is a new cylinder with about 17 hours since work done?  

This is a continuation of this thread: 

 

[Rick Junkin]

What was the EGT of #4 relative to the other cylinders before the top overhaul? If it was more in line with the other cylinders, did you change anything that might have caused a repositioning of the #4 EGT probe? It sounds like you are seeing something different from what you've been accustomed to and it raised a question. Always good to look into something that has changed.

Generally the peak EGT of each cylinder and when it occurs relative to the other cylinders is the important measure, and absolute values of the EGTs relative to each other is not. I see the same 100Fº spread across my EGTs and attribute it to the varying placements of the EGT probes in the exhaust risers.

[DC_Brasil]

Hi Alan,

Do you have your engine monitor data to share? Before and after the top overhaul would be nice, so we can see what you're seeing. 

Please do not take this question as offensive, but, did you read the answers on your original topic? 

EGT alone means veeeery little to diagnose engine or cylinder health. It tells more about the ignition process than anything. 

Many factors influence EGT readings and without looking at the data it is impossible to know what you're looking at.

Just so you sleep at ease (and as an example): your new cylinders will have very clean and perfectly working exhaust valves, which now let exhaust gasses out more efficiently. This could be one reason you're looking at something that seems different than before the overhaul. However, only the data will tell.

Without that, our guess here is as good and useful as a flat tire.

 

 

[Alan Maurer]

Hi Rick, Prior to the top overhaul ( all new cylinder) the EGT spread  was about  the same across six cylinders. The $4 is still about 100 degrees higher. so it got my attention. The CHT's all look good  and equal. Did switch the #4 with #6 , but EGT #4 is still hotter. Don't know why??

 

[Alan Maurer]

Well, I never saved or collected any data.  I thought that the engine data was stored in the MFD upper SD card  but it never seemed to work or I did not figure it out. 

Can get Sarasota Avionics in Venice to look in the #4 cylinder just to be sure it looks OK. Otherwise  hopefully we will figure it out!

[mhrivnak]

Are you running rich of peak? A clogged injector or other restriction on fuel flow to that cylinder will cause it to run less rich / more lean, which would give it a different EGT than the rest.

You might learn something about the problem by doing the GAMI lean test and seeing where/when that cylinder peaks relative to the others.

[Shadrach]

Raw EGT numbers are really not very useful except for at takeoff power.  What’s the egt on takeoff?  Have you leaned on that cylinder? What’s the peak number? It would be good to know that that that cylinder is at least 250° ROP when full rich.

[Alan Maurer]

For today's flight , take off always full rich. I don't fly LOP. I tried it once and about 12 knots slower than usual. Mooney's are meant to go fast!. So I do ROP. usually seems to work out to 17 to 18 GPH. I will take a good look at EGT's on take off

 

[Shadrach]

55 minutes ago, Alan Maurer said:

For today's flight , take off always full rich. I don't fly LOP. I tried it once and about 12 knots slower than usual. Mooney's are meant to go fast!. So I do ROP. usually seems to work out to 17 to 18 GPH. I will take a good look at EGT's on take off

 

I’m not advocating any particular way of running your engine.  I’m just trying to help you troubleshoot a potential issue and also make sure that you don’t have a lean cylinder on take-off. There’s a good chance that there’s nothing wrong with yours at all and that you’re getting hung up on something that doesn’t really matter like raw numbers that agree.

 

 

on takeoff.

[hazek]

13 hours ago, Alan Maurer said:

So...question....

Find a way to record the data and upload a flight to savvy and share the link, let's see the data. Hard to say anything without that.

[hazek]

12 hours ago, Alan Maurer said:

Can get Sarasota Avionics in Venice to look in the #4 cylinder just to be sure it looks OK.

If I were you I wouldn't do this unless they are asking for your data first and taking a good hard look at that first. To understand why that is important watch this:

 

[Rick Junkin]

14 hours ago, Alan Maurer said:

Well, I never saved or collected any data.  I thought that the engine data was stored in the MFD upper SD card  but it never seemed to work or I did not figure it out. 

Can get Sarasota Avionics in Venice to look in the #4 cylinder just to be sure it looks OK. Otherwise  hopefully we will figure it out!

@Alan Maurer Alan, if you do go to Sarasota Avionics first ask them to help you get your G1000 set up to record the engine data. Do this and go fly a few times to collect data and get it analyzed before you ask them to put wrenches on the engine. You mentioned your CHTs look good, so you aren't going to hurt anything flying it the way things are. Assuming your cruise EGTs are all nominally around 1500-1550ºF or less you aren't stressing your exhaust either.

100Fº variation across EGTs in cruise is common and this may be your new normal, but the engine data will verify that or point to what you need to take a look at.