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Dynon Skyview,EGT on#4

R

ron sterba

Well Known Member
Flying RV9A with 11 hours and noticed when I turned the master switch on #4 EGT reading is absent with a red line through the zero value. I replaced the spade connectors at the probe leads at the harness that goes to the ems unit. Same problem,value still X out. I made sure the clamp was tighten to max on exhaust pipe but still the X out. Since the # 4 CHT was only 8 degrees from the other CHTs and the engine was running smooth that I would take a flight. I was in the pattern after my takeoff and noticed that # 4 EGT was working and 12-15 degrees from the other 3 cylinders temps. I later landed after a hour flight and #4 EGT WAS STILL WORKING when I shut down. I thought it fixed itself cool!! (NOT) because when I went to the hangar the next day and turned on the master switch just to see the ambient temp readings on EGT,CHT AND OIL temps that #4 EGT was X out again. This is where I need your thoughts and suggestions. One question I have is,,,, is there a grounding issue with the probe clamp on the exhaust pipe?
Always appreciate your help.

Cheers

Ron in Oregon RV9A
 
I've been slowly replacing my EGT probes with Dynon's newest part number, over the last few years, as they fail. I've tried recrimping them, etc., but they just seem to fail and there's no reviving them. Usually it's a wonky reading (jumping around, going off-scale high, then dropping out completely), but they've all failed in slightly different ways as seen on the screen.

Just pop a replacement in...don't bother to fight it. They're fairly cheap.
 
Thanks Joe, that was spot on failure like mine. Yep the number valve just kept going crazy. Good to know they are cheap to buy. Should I buy them as they fail or just replace them all at the same time? Was wondering are they the same manufacturer?

Thanks Joe
 
Dynon EGT probes

Hi Ron,
13.2 hours, three EGT probes. Pleased to see they're supplying a different now. I'm equally pleased to say I've had 3 1/2 hours of trouble free flying now.
 
I've chased a couple of these EGT probes behaving exactly that same way. Erratic and/or failed and jumping around. It has been the probe itself each time, and I've run the gammut checking wires, connectors, etc in each case. Only working solution for the cases I've dealt with: Replace the probe with a new one, and discard the old one.
 
Probes

To trouble shoot you can try swapping the egt wires or probe from adjacent cylinder and see if your problem moves from#4 to #2. This should indicate if it's the probe or wiring. Any crimp or connector is suspect. Have someone watch the display while wiggling and tugging on all connectors.


Don Broussard

RV9 Rebuild in Progress
57 Pacer
 
EGT issues

I have had a couple of EGT issues over the years. I just replaced one that behaved exactly like the original posters. "X"ed out at abient and then once the engine warmed up work fairly accuractly. This was an internal EGT failure.

I also had one that would wildly display extemely high readings almost instantanously and then return to normal. This was a connector crimp issue. The older Dynon EGT factory crimps on both the EGT and CHT probes weren't solid and needed additional crimping to cure the issue.

Word of advice. Check the crimps on all your EGTs/CHTs before installation and make sure there isn't any movement between the thermocouple center core wire and the crimp.
 
Pmerems said:
Word of advice. Check the crimps on all your EGTs/CHTs before installation and make sure there isn't any movement between the thermocouple center core wire and the crimp.
Click to expand...

I had the same issue and this is GREAT advice. For some reason it always seems to be EGT #4 that gives the problem. In over 300hrs, have not had any problems with the other 3 EGT's.
:cool:
 
This is great news in that a clear trail to the failures is the probe itself. I'll swap the leads 4 & 2 to make sure. Crimps,,,, good idea to check. You expect a product to be precise but these many failures,,,, on new equipment, has anyone got FREE replacement probes from Dynon? Or have you all bought them from Dynon or just gone to other suppliers? Sounds like the replacements are good products. Thanks, I'll get back after I swap the probe wires later to day.

Ron in Oregon
 
I've replaced several of the Dynon EGT probes and they were all intermittent like described before they outright failed. The newer ones seem to be holding up much better!
 
Yep that # 4 EGT PROBE IS ON ITS WAY OUT,,.... thanks Bruce good to know that the replacements are better quality! Just finished installing the Koger sunshade in my 9A slider. It's a welcomed addition to the cockpit. Bruce how many hours on that new plane? Got 11 on my since September, we set all time record rainfall of over 11" in October. Three days that it didn't rain, November and December were near record too. Ski areas 100 mile east. Of here with over 120" of snow base. Flying days have been very limited. Better days on the horizon.

Thanks for all comments , always appreciated.

Cheers
Ron in Oregon RV9A N421HJ
 
An easy way to check the integrity of the wires is to short them together. The display should show ambient temperature. If it does, then you know that the wires and connections are fine between the short and the EMS. This test works for both EGT and CHT.
 
Hi Joe, yes the ambient temperature is missing and the values just keep running up and down. Stephen I replaced the spade tip connectors. I got thinking today about my #4 EGT in that the failure is when it's cold but start working when the temp gets past 400 degrees. Something is expanding from heat and making a connection. I looked at the probe itself and thought about placing this bad probe on my sanding belt and grinding away half the metal length wise to reveal the cut away cross section. It will be a first for a novice builder. I should really say novice at engines but not frame building. Be interesting if I can see what failed, like a crimp in the metal of the probe shaft. Course I don't know what it's suppose to look like. I thought maybe a little Bic lighter at points all the probe shaft to see if I could get it working again. Always looking for knowledge. Nothing overwhelming of course. That's why we post here. Thanks Doug.

Happy New Year
Ron in Oregon RV9A
 
Well got the new Dynon probe from Pacific Coast Avionics and installed it and iam back to normal hangar temperatures on all probes. Been working fine for a week now. Hey guys thanks for your ideas and testing techniques. It was a learning experience and that's a good thing. Much appreciated!!!!

Ron in Oregon RV9A N421HJ next to a Honda Jet but a whole lot more fun!
 
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