EGT probe change?

[swatson999]

So here's the history:

EGT probe on #4 cylinder went bad...recrimped, worked okay for a while, then went bad (values jumping all over, etc.), recrimped, okay for a while, then went bad again. Finally after 3 recrimps gave up...debugging (watching EFIS values while a partner messed with the connections, changed to a replacement probe, etc.) led us to swap out the probe entirely for a replacement one (from ACS), after we figured out it wasn't the crimp, but somewhere upstream of the crimp/connection that had gone bad. No big deal, it happens.

New probe is working fine, BUT...it's reading 50 degrees higher than previously, and during run-up (to clean a fouled plug on #1), it went WAY high, > 1600 deg F. I realize that EGT absolute values are worthless, because they depend on location, and after cleaning the plug at 2000 RPM, then completing run-up, everything was fine. Test flight was nominal, except for #4, with the new EGT probe, was consistently about 50 deg F higher than all other cylinders (and what it had been when not acting up).

So my question...is there a new/revised part which has been put into service by Dynon for EGT probes? If so, I'm contemplating changing all my EGT probes at annual in December...if not, why the sudden increase in EGT values (and the way high value during plug cleaning at 2000 RPM and lean to max during run-up)?

TIA...

Steve

 

[swatson999]

I see I'm not the only one questioning the EGT probes, and that others are also seeing higher values (and someone also saw *extremely* high values at one point)...

http://dynonavionics.com/cgi-bin/yabb2/YaBB.pl?num=1375333390/4#4

Are the (possilby) new EGT probes bad? Is there a better brand or manufacturer of these things.

I *really* don't want to waste time chasing these down cylinder by cylinder, probe manufacturer by probe manufacturer, etc.

 

[jc2da]

Steve, I will post an update on my thread that you refer to.

The most important thing is to realize that the new EGT probes are different. Do NOT go chasing this red-herring thinking it is a cylinder or fuel issue like I did. Very frustrating!

 

[swatson999]

Still looking for confirmation from tech support here...did they change EGT probe design/supplier? Why is the newly installed one reading so much higher than the old one?

 

[Dynon]

We do change suppliers / etc from time to time, and definitely have in the past on EGTs. We didn't think there were any functional differences between them, though, although this thread is clearly pointing out that there is. We're currently looking into this issue.

 

[rlallen1]

After 70 hours my dynon provided EGT probe on #4 went bad, temps all over the place erractically. I checked all the crimps, recrimped, switched EGT probes to alt cylinders...and came to the conclusion it was toast.  They are all placed about 2 inches from the base of the cylinder.  I called Dynon tech support and was basically told they do not provide the highest quality EGT probes and I should just expect them to have be replaced.  I had very good reports from people using EGT probes from www.ksavionics.com.  They are more expensive, but much better quality than what Dynon sent.  i went ahead and replaced all the probes at once. 

I have not had any further issues in the EGT probes since.

the KSAVIONICS warranty was nice too...  was quite surprised dynon did not warranty a bad probe with 70 hrs..

Probes made by KS Avionics have a 2-year or 1,000-hour (whichever occurs first) warranty.

 

[mmarien]

I fried all mine but my EGTs are typically in the 1550F range.

https://www.savvyanalysis.com/flight/385648/863830d4-7ade-49df-ae35-1b1d6bffa815

I replaced the Dynon probes with urlrobes that were made to handle 2000F but they cost me $100 each. I had no problems with them since I replaced them 55 hours ago.

 

[ned]

These are the probes I plan to purchase and install soon. Claim is 2375f. As an added bonus they told me that they will make them shorter to spec at no additional cost.
http://thesensorconnection.com/egt-probe-thermocouples/sensors/exhaust-gas-temperature/egt_muffler_clamp_probe.shtml

 

[swatson999]

We do change suppliers / etc from time to time, and definitely have in the past on EGTs. We didn't think there were any functional differences between them, though, although this thread is clearly pointing out that there is. We're currently looking into this issue.

Bumping this up...any word on this? I'm coming up on annual condition inspection in a couple of months and have a list of several items to replace (Dynon capacitive convertors to change to Princeton, etc.), and this would be a good time to swap out the 3 remaining EGT sensors if there's been a change. #4 (with the new EGT sensor) continues to read 50 degrees or so higher, but it's stable, than all the others (which violates my sense of order and symmetry in the universe).

TIA...

Steve

 

[Dynon]

We're still looking into this, and one of our engineers may be in touch with some of you via PM to solicit more information.

 

[Hotscam]

I had three EGT sensor replacements in 230 hours of flying.
I do have only 2 installed out of 4 cylinders on the Rotax
Not very reliable type and a hell of a job to replace in the RV12

Jack

 

[phvdw]

why always #4 ; same problem after installing version 7; nothing done after restarting 2 or 3 times SV all normal again; EGT are 1 hour on motor

 

[TRCsmith]

What EGT range are you looking for? Does your engine have a limit if so what is it???

 

[skydancer]

I've noticed all the guys who have bad probes are running high EGT (correct me if you are not).

I know EGT is irrelevent but I still run mine around 1350F, and my Dynon probes are still as good as new (I checked), I have over 250 hours on them.

I did replace all the crimp terminals on them.

 

[mmarien]

I know EGT is irrelevent but I still run mine around 1350F

All depends on whether 1350F is from LOP or ROP. If you're LOP then the cooling is coming from air. If your ROP then the cooling is coming from fuel. If I enrich to peak power I'm burning 40+ lph (AFR=13). If I lean to about AFR=15 or just slightly LOP EGT. I get 30 lph or better with altitude. That a reduction of 10 lph or $20/hour or $2G/year.

With those numbers, I can treat $35 EGT probes as a consumable. My $35 EGT probes started burning out at ten hours and none lasted more than about 50 hours at 1500+ EGT temperatures. My current $100 EGT probes have 90 hours on them and are still working but they are paid for with the fuel savings anyhow.

 

[swatson999]

I've noticed all the guys who have bad probes are running high EGT (correct me if you are not).

I know EGT is irrelevent but I still run mine around 1350F, and my Dynon probes are still as good as new (I checked), I have over 250 hours on them.

I did replace all the crimp terminals on them.

Nope. Mine run around 1300-1350, and my #4 EGT probe failed. The new one (different vendor?) is working fine now for, oh, I dunno...40 hours or so I'd guess.

 

[skydancer]

I've noticed all the guys who have bad probes are running high EGT (correct me if you are not).

I know EGT is irrelevent but I still run mine around 1350F, and my Dynon probes are still as good as new (I checked), I have over 250 hours on them.

I did replace all the crimp terminals on them.

Nope.  Mine run around 1300-1350, and my #4 EGT probe failed.  The new one (different vendor?) is working fine now for, oh, I dunno...40 hours or so I'd guess.

What does your #4 probe looks like when it came out exhaust pipe?

 

[swatson999]

I've noticed all the guys who have bad probes are running high EGT (correct me if you are not).

I know EGT is irrelevent but I still run mine around 1350F, and my Dynon probes are still as good as new (I checked), I have over 250 hours on them.

I did replace all the crimp terminals on them.

Nope.  Mine run around 1300-1350, and my #4 EGT probe failed.  The new one (different vendor?) is working fine now for, oh, I dunno...40 hours or so I'd guess.

What does your #4 probe looks like when it came out exhaust pipe?

Pretty much just like the one that went in, maybe a little bit of color change due to heat.

In other words, it was intact in appearance, but failing in operation.

In any case...I'm still waiting to hear if Dynon has changed vendors or parts, since the replacement definitely reads higher than the previous one (and the other 3 sensors).

 

[skydancer]

Hi Steve,

I re-crimped my #4 twice, after the 3rd fail, I simply replaced the connector with Molex pin/connector which I was sure that it would guaranty a good contact, that's about 100 hours ago before I went to Alaska in June. and it has held up very well.

Are you sure your #4 is a bad sensor and not a bad crimp again? did you dip in the hot oil and check for the reading before determine it's a bad sensor?

 

[jakej]

This may help resolve the issues in some cases -  the supplied spade connectors are too solid ie they are very hard to crimp (even with a good quality crimper) & therefore do not crimp well.  I throw out the supplied 'pink' coloured ones & replace them with the red AMP ones.  There are several other factors involved with the terminal joints & pins on the thermocouple wires, a search of the posts will find them. 
I have installed literally hundreds of them & had only 2 failures, guess I'm lucky  :-/

Jake J