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  #11  
Old 05-22-2016, 06:00 AM
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f1rocket f1rocket is offline
 
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Thank you for all the replies. I have 202 hours on the airplane as of today. The probe has been acting this way for some time so I'm not sure when, in terms of hours, it started happening. I used to get a big red X on one of the probes until I redid the connections, tightened them up, and wrapped them in silicon tape. My limits are set at the original Van's set-up limit, which I think is 1480 F or there about.

I'm pretty sure the probe is probably going bad so it wasn't so much of a question of "what to do" but more of a "what's the big deal". I don't know what value the EGT is on a Rotax since there's no leaning. I guess it would be a quick indicator of a fuel/carb problem on one side of the engine.

I may bump the limit to eliminate the warning until the probe fails completely. I'll replace it then.
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  #12  
Old 05-22-2016, 10:17 AM
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Just one more point... Perhaps take into consideration that the probe isn't bad.
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  #13  
Old 05-22-2016, 12:15 PM
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TomVal TomVal is offline
 
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FWIW,

I recently had a similar problem on my Jabiru engine with GRT instrumentation. Discovered an open ground on the #2 probe. This open ground was affecting all of my EGT indications.

Ordered a new probe set from GRT and problem solved. They sold two types of probes, one type was a more durable longer lasting probe. They said the less durable set typically failed around 150 to 200 hours. My probe failed at 145 hours.

Don't know if Rotax uses the same probe manufacturer. I think I paid $13/probe more for the higher quality set.
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  #14  
Old 05-22-2016, 04:51 PM
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Piper J3 Piper J3 is offline
 
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My right EGT indicates about 80F higher than the left EGT at cruise power setting. I?m curious if others experience anything similar. Perhaps right carb/cylinders are making slightly more power than left side? Engine/prop run extremely smooth...
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Jim Stricker
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80 hrs Flying Aeronca Chief 11AC N86203
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Bought Flying RV-12 #120058 Oct 2015 with 48TT - Hobbs now 622

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  #15  
Old 05-22-2016, 05:23 PM
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Quote:
Originally Posted by Piper J3 View Post
My right EGT indicates about 80F higher than the left EGT at cruise power setting. I?m curious if others experience anything similar. Perhaps right carb/cylinders are making slightly more power than left side? Engine/prop run extremely smooth...
This is exactly what mine is doing.
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Greenwood, IN

www.pflanzer-aviation.com
Paid through 2043!
Lund fishing Boat, 2017, GONE FISHING
RV-12 - Completed 2014, Sold
427 Shelby Cobra - Completed 2012, Sold
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  #16  
Old 05-22-2016, 06:30 PM
cactusman cactusman is offline
 
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That is exactly what mine did, I removed all the connectors, did a recrimp of all new connectors and it still read high..then started going wonky every once and while....

Put a new one in and it reads fine.

Probes, floats and regulators boys...probes and floats and regulators.
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  #17  
Old 05-22-2016, 06:41 PM
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Piper J3 Piper J3 is offline
 
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Quote:
Originally Posted by cactuspilot View Post
That is exactly what mine did, I removed all the connectors, did a recrimp of all new connectors and it still read high..then started going wonky every once and while....

Put a new one in and it reads fine.

Probes, floats and regulators boys...probes and floats and regulators.
To clarify... You installed a new EGT and it fixed wonky (your term) readings and also right side reads ~80F higher than left side?
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Jim Stricker
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PPL/ASEL 1970 - Sport Pilot since 2007
80 hrs Flying Aeronca Chief 11AC N86203
1130 hrs Flying 46 Piper J-3 Cub N6841H
Bought Flying RV-12 #120058 Oct 2015 with 48TT - Hobbs now 622

LSRM-A Certificate 2016 for RV-12 N633CM
Special Thanks... EJ Trucks - USN Crew Chief A-4 Skyhawk
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  #18  
Old 05-22-2016, 07:48 PM
cactusman cactusman is offline
 
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Quote:
Originally Posted by Piper J3 View Post
To clarify... You installed a new EGT and it fixed wonky (your term) readings and also right side reads ~80F higher than left side?
Yes, my EGTR has always read a little higher during it's non-wonky stage. I think it is the proximity to the oil tank...I have tried a little fire/heat wrap around the end of the probe when it gets close to the tank to no avail.

Pre-Fail and high and sometimes wonky:



New Probe still reads a little higher:

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  #19  
Old 05-22-2016, 08:28 PM
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Piper J3 Piper J3 is offline
 
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Thanks for the confirmation. Proximity of oil tank could explain differential in EGT's.

Love VAF...
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Jim Stricker
EAA #499867
PPL/ASEL 1970 - Sport Pilot since 2007
80 hrs Flying Aeronca Chief 11AC N86203
1130 hrs Flying 46 Piper J-3 Cub N6841H
Bought Flying RV-12 #120058 Oct 2015 with 48TT - Hobbs now 622

LSRM-A Certificate 2016 for RV-12 N633CM
Special Thanks... EJ Trucks - USN Crew Chief A-4 Skyhawk
MJ Stricker (Father & CFI) - USAAF 1st Lt. Captain B-17H
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  #20  
Old 05-22-2016, 11:19 PM
Sink Sink is offline
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Do not allow any header wrap on the EGT probe.Do not over wrap or under wrap the probe. The header cloth should be at least 1/8" + away from the probe. Neither Dynon nor Rotyax know the exact cause of the interrupted EGT signal. It works on millivolts so it doesn't take much. It has demonstrated that the cloth and the probe are not compatible and can cause EGT temps to flux as much as 125F and usually to the high side. The oil tank will not effect the EGT probe. The probe is inside the exhaust pipe at temps around 1300F-1500F. The oil temp of 215F won't have any effect and the probe would have to be in the oil itself.

An EGT spread of 80F can be very normal for some engines. It depends on several factors. Carb sync, probe placement, internal carb wear, air filter, ect...
An EGT temp with only a 15F spread is considered the same. EGT temps differ with throttle settings and will move up and down and closer or farther apart depending on the throttle settings.


Bottom line don't worry about an 80F spread unless you know you did something that effected the burn and can correct it.
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