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I think I need a new EGT probe....

cactusman

cactusman

Well Known Member
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Ordered a new one today.....this was my post new carb float/re carb synch test flight....sigh....
 
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Had an erratic egt reading, re-crimped the connectors and used some heat shrink for strain relief .... No problems since.
 
I had two go bad in just under 100hrs.
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Maybe you have them too close to the flange? I believe 2-4 inches, but closer to 4 inches will make them last longer.
 
If you are fuel injected I would clean the injector on that cylinder. Also check to see if the cold temp prior to start up is similar to the other 3 probes. If it is way off from the resting temperature of the other 3 ,that would be the probe or its wiring....
 
Rotax EGT

I've got over 800hrs behind Rotax 912s. Just check the probe I've had trouble with them a couple of times. In the meantime I wouldn't worry about it. It obviously couldn't be that high with the other temps OK.
 
I've had three go out in 130 hrs. Dynon was kind enough to replace the first two at no charge, but with this third one I gotta think it is something with my installation? These things are pretty simple and I thought durable, not sure what could be causing this?
 
Thanks all - I ordered 2 - same shipping. Not sure if mine is still covered on warranty or not - checking on the dates - I did check the crimps and connections - it always ran hot and now it seems to be going nuts. I'll R/R and hopefully that will fix it.

Anyone do anything special with the probe on that right side with the close proximity to the hot oil tank?

As an aside - this was my first flight also with the RVbits fairings and Van's wheel pants installed as well - seems like I am 10 KIAS faster across the board! And my ball is still centered so I guess I got everything on straight.

Need to tweak my fuel flow a little as well.

But what a nice ride this airplane is! I am really having fun flying this plane despite some of the headaches.
 
Have you thought about swapping probes from a good cylinder into the bad cylinder, like put the #2 probe (wire and probe) into the #4 cylinder, so you will be reading the temp of #4 with the #2 bar on the read out. If you still see the temp spike then you know for sure it is not the electronics.
 
CATPart said:
Have you thought about swapping probes from a good cylinder into the bad cylinder, like put the #2 probe (wire and probe) into the #4 cylinder, so you will be reading the temp of #4 with the #2 bar on the read out. If you still see the temp spike then you know for sure it is not the electronics.
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I did think about it - but I will have to remove the oil tank to get at it I think.... which means I will have to repressurize the oil system on the RV-12...not a huge deal, but just more work. If I am going to do that, I might as well replace it for 34 bucks and move on.
 
I'd check the probe first. My short time experience has been that the EGT and CHT probes aren't worth c**p. I've replaced four already at 34 hours on the engine. Two of the CHT were bad right out of the box.
 
Another possibility is routing of the wire from the probe. I recently had a similar problem that was caused by the EGT probe wire running parallel to the landing light wire for a few inches. That was enough to get a little stray voltage on the EGT wire and give me ~2000F EGT on one cylinder. I rerouted the wires and that cured the problem.
 
Me too

I also had one go bad in the first 100 hours-- Loud alarms and all the fun. Replacement still working fine after 200 more hours.

Wayne 120241/143WM
 
I just replaced my left probe at 260 hrs time in service. It was spiking high. I tried re terminating the probe to no avail and swapped inputs to verify the failure. The Dynon replacement was also bad, but its symptom was that it peaked at about 500 F. Three was the charm. The second replacement works as advertised.
 
Dynon EGT probes

Dynon or the manufacturer of their EGT probes use a double over inside the crimp and they give trouble often. Recrimp with a GOOD crimp tool. If you have a ratcheting type per AC43 use it but stay away from the cheap automotive style. I have repaired numerous Dynon (bad) EGT probes like this. The malady is the crimp is somewhat loose creating a higher resistance in the joint and the EGT probe is a thermocouple and it is all about resistance.

Tyler
N174MT
K4NLM
A&P
 
RFSchaller said:
I just replaced my left probe at 260 hrs time in service. It was spiking high. I tried re terminating the probe to no avail and swapped inputs to verify the failure. The Dynon replacement was also bad, but its symptom was that it peaked at about 500 F. Three was the charm. The second replacement works as advertised.
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Glad she talked me into buying two then....
 
I just had one plug stop firing (there are 2 plugs in each cylinder) with only one plug firing on that cylinder it resulted in a significantly higher EGT with a correspondingly lower CHT. That was on my Lycoming not my wife's Rotax 912S.
 
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