Blue zone on EGT

[rgpilot]

When I purchased my Ovation 2 the EGT probe for the factory installed EGT gage with the blue box had just been replaced. I think it may have the wrong probe. Alcor has them with different resistances. The readings I get are always higher than the readings on the JPI by about 100 degrees. The JPI probes are installed close to the cylinders and the factory probe is installed where the exhaust pipes merge. Should it not be cooler further away from the cylinders? To try to keep the needle in the blue zone allows almost no leaning.

Does anyone know the correct part number or correct Alcor number?

[carusoam]

If it helps...

You have described the JPI EGTs and the ship's gauge correctly...

See if you can contact Mooney to see if you have the correct part in there already...?

My O falls out the bottom of the blue box when it climbs...(I don't recall the exact details)

Best regards,

-a-

[Cruiser]

actually the ship's gauge should read higher than the individual EGT probes on your JPI.

 

The factory probe is reading the combination of heat from all three cylinders on that side of the engine. The JPI probes only get heat from one cylinder so they have time to cool between exhaust cycles. 

 

However, if your replacement is not performing similar to the old probe (why was it changed?) there may be some other problem.

 

the probe is an ALCOR, the part number is 86255 in my parts manual.

http://www.mcfarlane-aviation.com/Products/?PartNumber=86255

[Cruiser]

19. EXHAUST GAS TEMPERATURE (EGT)

A thermocouple probe, located at junction of #1, 3 & 5 exhaust pipes, transmits temperature

variations to the indicator which serves as a visual aid during leaning. EGT varies with fuel-air

ratio, power and RPM. Engine operation within BLUE ARC, during climbs, provides sufficient

fuel to keep engine power within proper temperature range. Location may vary.

 

note: My location is at the junction of #2,4 & 6. Opposite side. 

BLUE ARC 1400 - 1450 °F

The BLUE ARC is an aid for climb and more importantly DESCENTS that require power to keep the engine from cooling too quickly.

I routinely run the factory EGT above the BLUE ARC in CRUISE. 

[rgpilot]

The probe was replaced because it had failed. If about 100 degrees above individual egt probes seems correct then its probably the correct probe. The log book shows it was replaced with a part # 86255. When I am in cruise, it always indicates above blue arc. Thanks for the help.

[M20R]

I had the same problem. The JPI was more that 100 degrees different than the Moritz gauge. I swapped out the sender and no change. I then found that the Moritz EGT gauge can be adjusted. There are trim pots on the side of the Moritz gauges. The maintenance manual has the procedure.

 

D.I.

N1020A

[Cruiser]

The probe was replaced because it had failed. If about 100 degrees above individual egt probes seems correct then its probably the correct probe. The log book shows it was replaced with a part # 86255. When I am in cruise, it always indicates above blue arc. Thanks for the help.

my last flight was at 6000' and -14°C, Baro was around 30.07 from memory.

from my JPI file I was running 68% HP @ -72 LOP 

RPM 2330 MAP 23.2

FF 14.1

#4 EGT 1449 (about in the middle of the spread)

Factory probe was around 1530 from memory.

[Bob - S50]

 

19. EXHAUST GAS TEMPERATURE (EGT)

A thermocouple probe, located at junction of #1, 3 & 5 exhaust pipes, transmits temperature

variations to the indicator which serves as a visual aid during leaning. EGT varies with fuel-air

ratio, power and RPM. Engine operation within BLUE ARC, during climbs, provides sufficient

fuel to keep engine power within proper temperature range. Location may vary.

 

note: My location is at the junction of #2,4 & 6. Opposite side. 

BLUE ARC 1400 - 1450 °F

The BLUE ARC is an aid for climb and more importantly DESCENTS that require power to keep the engine from cooling too quickly.

I routinely run the factory EGT above the BLUE ARC in CRUISE. 

 

 

Why worry about EGT?  If you are concerned about cooling, watch the CHT.

 

Which JPI do you have?  If its a 730/830, you can check the cooling rate by looking at the CLD readout.  If its the 700 I don't know what to tell you other than watch the CHT temps.

 

Bob

[carusoam]

The R has a recommended ROP setting for climb. Pretty much setting up EGT for climb...

The needle is within a range indicated by a blue box.

The ship's guage is in the confluence of three exhaust streams to best represent what the engine is doing...

That's the why for having the right thermocouple in that location...

Original Rs may not have been equipped with JPIs. Mine was added in early...

Best regards,

-a-

[Txbyker]

Trying to tag this post to a thread close to the subject.  I had a faulty 2,4,6 collector probe.  My #4 runs 50 degrees hotter than the others so I replace it too.  Same part number.

 

Symptoms - G-1000 summary page showing EGT in the 100's degrees whereas the engine page showed each cylinder in the mid 1400's

Part Number - Alcor 86255.  On mine same EGT probes on cylinders and exhaust collector.

Cost - $83.75 at Aircraft Spruce

 

See picture.  I run LOP and the probe is pitted pretty bad.  750 total hrs.

 

Russ