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EGT probe lifetimes?

airguy

airguy

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I lost my #4 EGT probe at 11.9 hours TT, just got the replacement in today and I'll install it tomorrow. These are the Dynon probes, and they are mounted very close to the exhaust flange so I'm seeing EGT's in the 1400-1500 range. I know these probes have finite lifetimes and are a normal "wear and tear" item but I would not have expected a failure this early.

I'm going on the assumption that I've got a statistical anomaly on this one, but what it is the expected lifetime of these probes?
 
airguy said:
I lost my #4 EGT probe at 11.9 hours TT, just got the replacement in today and I'll install it tomorrow. These are the Dynon probes, and they are mounted very close to the exhaust flange so I'm seeing EGT's in the 1400-1500 range. I know these probes have finite lifetimes and are a normal "wear and tear" item but I would not have expected a failure this early.

I'm going on the assumption that I've got a statistical anomaly on this one, but what it is the expected lifetime of these probes?
Click to expand...

I'd say the lifetime of the probes is usually 11.9 hours and up. :D

Good chance you got a bad one.
 
Dynon EGT probes

Just as a data point, I currently have ~ 130 hours on my install. No problems with EGTs yet. Being carbed, I usually lean to show ~ 1325-1375 degrees (still rich of peak by about 50-75 degrees or so). I did have one problem show up early on and ordered a replacement probe, but it turned out to be a bad connection at the fast-on tabs. YMMV. Bill
 
The hotter the EGT locale, the shorter the life. the highest EGTs mine ever see is ~1410F and they're holding up OK after 3 yrs. I run LOP at around 1350 EGTs the vast majority of the time.
 
airguy said:
I lost my #4 EGT probe at 11.9 hours TT, just got the replacement in today ...
Click to expand...
Dave, I lost one EGT probe at 80 hours. This was a common occurrence but Dynon states they have made "continuous improvements" (their words) to the probes (under the same part number). You can find numerous reports of similar failures on the Dynon Avionics forums.

My replacement probe and the other three originals are still working 2 years and 200 hours later.

--
Joe
 
There's a few reasons that probes fail. It's not just the element that separates but the cable is often the failure point. I just replaced an EGT probe that had a snapped wire inside the cable where it exits the element tube, under the spring. It's about 150 hours old. How you secure the wires in the looms can help reduce vibration.
 
FasGlas said:
There's a few reasons that probes fail. It's not just the element that separates but the cable is often the failure point. I just replaced an EGT probe that had a snapped wire inside the cable where it exits the element tube, under the spring. It's about 150 hours old. How you secure the wires in the looms can help reduce vibration.
Click to expand...

Aaahhh - now this sheds some light on the failure mode, a-la the Waddington Effect.

Just immediately prior to the EGT failure, I had rerouted my main fuel line from the firewall penetration to the servo, and had put in a couple clamps on the left side of the sump to hold it securely. I had removed the #2 and #4 intakes to make tool and finger room, and I remember bumping the #4 EGT a couple times and trying to be careful about that. The next engine start the EGT was dead, now I'm pretty sure I know why.
 
We do generally see failures from maintenance and other stuff than just raw wear. The only probe failure on my plane with 850 hours on it was the one I pulled at 400 hours to "see how it was doing" and it never worked after that ;)

I'd generally say that with an install which runs at 1500 EGT, we'd expect at least 800 hours before the probe wears out from the exhaust gasses.
 
Probe fine but connectors poor

I started to get noisy indications on my #4 EGT around 100 hours. I tried re-crimping the connectors but that only lasted a few hours. I got a new sensor and that fixed the problem but beware the core wire is solid and so easily damaged by repeated flexing or bending. In fixing the #4 probe the gentle wiggling of adjacent wires caused the #2 sensor to fail. So I had the joy of installing another one.
Cheers
Nigel
 
I bought a set of 6 probes from a builder here who was going to put them into a six cylinder engine. I used 4 and had 2 spares. I had intermittent issues with one, and then yet another one just failed outright at around 100 hours. I put in my 2 spares and had yet another of those fail within another 50 hours. I bought a single EGT probe replacement at Aircraft Spruce and have been OK for the last 50 or so hours. So 3 out of the original six failed early.
 
airguy said:
I'm going on the assumption that I've got a statistical anomaly on this one, but what it is the expected lifetime of these probes?
Click to expand...


My single JPI probe on #3 is measuring CHT for more then 2,300 hours and I expect it to last couple hours more. I am assuming I am a statistical anomaly on the other end :)
 
Vlad said:
My single JPI probe on #3 is measuring CHT for more then 2,300 hours and I expect it to last couple hours more. I am assuming I am a statistical anomaly on the other end :)
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CHT, sure - my problem was EGT.

400 degrees versus 1500 - big difference on expected lifetime
 
Vlad, CHT and EGT are very different measurements to make. EGT probes wear out because they're in the 1,500F exhaust stream with corrosive gasses. Making a CHT last forever is pretty easy.
 
EGT failures

I lost all my GRT EGT probes around 250 hrs, the tips had literally melted off. My probes are located 2" from the cylinder flange. I now have 370 hrs and it appears one EGT probe is failing again.
GRT started carrying more expensive probes they claim are longer lasting. I have them now but not yet installed.

On my Long-EZ I had ECI probes which lasted 1,000 hrs. Guess they just don't make them like they use to!!
 
I try to put my EGT probes about 2.5" from the exhaust flange, and have had no failures on the RV-8, which is now at 1800 hours, or on the -3, which is just over 500. I have lost track of the number of hours on Louise's -6......
 
I still have All original JPI probes with over 700 hours and always fly leaned to EGTs of over 1500F.
 
probes

I now have over 900 hours on mine. No problems yet always run lop. Now that I say that I may as well call Dynon and order new ones.
 
GRT Probes

rv9av8tr said:
I lost all my GRT EGT probes around 250 hrs, the tips had literally melted off. My probes are located 2" from the cylinder flange. I now have 370 hrs and it appears one EGT probe is failing again.
GRT started carrying more expensive probes they claim are longer lasting. I have them now but not yet installed.

On my Long-EZ I had ECI probes which lasted 1,000 hrs. Guess they just don't make them like they use to!!
Click to expand...

I have circa 2006 GRT EGT probes with 530 hours on them, mounted 1.5 inches from the exhaust port flange on an IO-360 angle valve. No issues to date.

Skylor
 
I have Advanced Flight probes. No idea where Rob sources the probes. 650 hours and replaced one @ 500 hours. Mine are 4" below the flange and run 1350F when leaned.
 
Dynon EGT probes here. First one went at around 75 hours. Second one around 150 or so. All good until recently, then two of them started to go at 350-375 hours. Same symptoms on all of the failures...ratty EGT values, jumping all over the scale, then eventually reading off-line.

At first I tried re-crimping the connectors, but that was only a temporary fix.

Probes are about 2.5" from the flange IIRC. Hopefully, the latest replacements last month with "new and improved" probes will result in longer lifetimes. We'll see. I get tired of replacing them, and oftentimes wonder why there is no better method of reading EGT.
 
rv9av8tr said:
I lost all my GRT EGT probes around 250 hrs, the tips had literally melted off. My probes are located 2" from the cylinder flange. I now have 370 hrs and it appears one EGT probe is failing again.
GRT started carrying more expensive probes they claim are longer lasting. I have them now but not yet installed.

On my Long-EZ I had ECI probes which lasted 1,000 hrs. Guess they just don't make them like they use to!!
Click to expand...

At 500 hrs, I have one of the 4 original"light duty" GRT probes still in service. Replacing with heavy duty GRT probes as they fail. Operating temps typically 1430 F.
 
I started this thread so I thought I would circle back - I got the replacement EGT sensor and started to change it out, and thought I would check the connections first. They were good and tight but I pulled them apart and reconnected them anyway and cranked it up.

Anyway, now I've got a spare EGT for when one really DOES fail... :D
 
One high egt probe

dynonsupport said:
Vlad, CHT and EGT are very different measurements to make. EGT probes wear out because they're in the 1,500F exhaust stream with corrosive gasses. Making a CHT last forever is pretty easy.
Click to expand...

Dynon, please could you tell me more about what symptoms a bad egt prob show? I just started flying my 7A, with your EMS and probes and I have just one egt probe that shows 200 - 300 F higher than the others on climb out or high power demand. Peaks at 1500F.
CHTs are fine. I'm debugging one item at a time. I'm hoping its the probe or connection and not something with the engine. Are there any tips about the wiring I should be aware of that I might have done? I have some slack and just looped it. I used your blade connectors.

Thanks
 
Does anybody have a reasonably good "guesstimate" of the relative change in EGT vs change in distance from exhaust flange?

I ask this because my AFS probes are all mounted at exactly the same distance from the exhaust flange, which also happens to be the lowest common denominator in distance available, i.e. one exhaust pipe had a bend in it which dictated the location of the EGT probes in all four pipes.

I frequently see EGTs running in the low 1500's with the probes 3" from the exhaust flange. I've also installed all of my probes such that the project inwards toward the core of the engine rather than outward where I'm more likely to snag them when doing routine maintenance. This method makes it a little more difficult to access the EGT wiring, but not very much more difficult. So far I've got 120 hours and still going strong...
 
sglynn said:
Dynon, please could you tell me more about what symptoms a bad egt prob show? I just started flying my 7A, with your EMS and probes and I have just one egt probe that shows 200 - 300 F higher than the others on climb out or high power demand. Peaks at 1500F.
CHTs are fine. I'm debugging one item at a time. I'm hoping its the probe or connection and not something with the engine. Are there any tips about the wiring I should be aware of that I might have done? I have some slack and just looped it. I used your blade connectors.

Thanks
Click to expand...

Switch it with the adjacent cylinder's probe and see if moves with the probe, or stays with the cylinder.
 
one spking egt

Turned out to be partially plugged fuel injector nozzle. Cleaned the nozzle and all is great.
 
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