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  #1  
Old 05-12-2020, 12:57 PM
jwilbur jwilbur is offline
 
Join Date: Dec 2010
Location: Culpeper, VA
Posts: 693
Default bad CHT probe

I replaced my Cylinder #1 CHT probe in 6/2019. The new probe has now also gone bad. Seems a little too coincidental.

Looking back through data, this new probe was perfectly fine until about this past March. I can see from that point on it's been getting progressively "jumpier" on each flight. It's especially bad when power is high. EGTs are all stable and well behaved.

Anybody have any idea what might be causing my #1 CHT probes to go bad?
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  #2  
Old 05-12-2020, 02:36 PM
Jonathan Alvord Jonathan Alvord is offline
 
Join Date: Feb 2018
Location: Prosser, WA
Posts: 107
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I have had similar issues, as well as the original builder of my RV7. #1 never works. I thought, and still do it is a poor connection/Wire crimp. Just need to go to mech and borrow a D-Sub pin crimper and re wire it sometime soon.

Jon
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  #3  
Old 05-12-2020, 04:08 PM
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RV8JD RV8JD is offline
 
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Dynon probes by any chance?
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Arlington, WA (KAWO)
RV-8, 790 Tach Hours
(Pic 1),(Pic 2)
- Out with the Old, In with the New
(Pic)
RV-8, 1938 Tach Hours (Pic 1),(Pic 2) - Sold

Glasflugel Standard Libelle 201B - Sold
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  #4  
Old 05-12-2020, 04:15 PM
jwilbur jwilbur is offline
 
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Quote:
Originally Posted by RV8JD View Post
Dynon probes by any chance?
Yes they are ???
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Phase II - 11/2017
First flight - 8/2017
RV-10 Build Log
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  #5  
Old 05-12-2020, 04:21 PM
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Carl Froehlich Carl Froehlich is online now
 
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Location: Dogwood Airpark (VA42)
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Try cutting off the connectors and replacing them with standard Fast-tabs. Add a piece of #20 wire in the connector with the probe wire - makes for a better crimp connection.

Carl
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  #6  
Old 05-12-2020, 04:27 PM
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RV8JD RV8JD is offline
 
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Quote:
Originally Posted by jwilbur View Post
Yes they are ???
Dynon probes, both CHT and EGT, have a bad rep. I've had a few of both fail. Some say it's the connectors and/or the crimps, so try Carl Froehlich's suggestion.
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Carl N.
Arlington, WA (KAWO)
RV-8, 790 Tach Hours
(Pic 1),(Pic 2)
- Out with the Old, In with the New
(Pic)
RV-8, 1938 Tach Hours (Pic 1),(Pic 2) - Sold

Glasflugel Standard Libelle 201B - Sold
Rolladen-Schneider LS1-f - No longer owned
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  #7  
Old 05-12-2020, 04:43 PM
jwilbur jwilbur is offline
 
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Location: Culpeper, VA
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Quote:
Originally Posted by RV8JD View Post
Dynon probes, both CHT and EGT, have a bad rep. I've had a few of both fail. Some say it's the connectors and/or the crimps, so try Carl Froehlich's suggestion.
Thanks. Will do.
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-Joe Wilbur (N520LW)
Phase II - 11/2017
First flight - 8/2017
RV-10 Build Log
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  #8  
Old 05-14-2020, 06:09 PM
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RV8JD RV8JD is offline
 
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I saw your other thread regarding your question on EGT #1, and wondered if you fixed your CHT #1 issue?
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Carl N.
Arlington, WA (KAWO)
RV-8, 790 Tach Hours
(Pic 1),(Pic 2)
- Out with the Old, In with the New
(Pic)
RV-8, 1938 Tach Hours (Pic 1),(Pic 2) - Sold

Glasflugel Standard Libelle 201B - Sold
Rolladen-Schneider LS1-f - No longer owned
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  #9  
Old 05-14-2020, 06:27 PM
jwilbur jwilbur is offline
 
Join Date: Dec 2010
Location: Culpeper, VA
Posts: 693
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Quote:
Originally Posted by RV8JD View Post
I saw your other thread regarding your question on EGT #1, and wondered if you fixed your CHT #1 issue?
I replaced the CHT probe. Problem was even worse. Then I rerouted the probe wires away from the plug. So far so good. Compared to the other CHT probes #1 wires were running very close to where the ignition wire enters the plug. Perhaps #1 is electrically noisier due to the other issue. ??

The EGT issue has been exactly the same since first flight. I think the two problems are Probably unrelated or only indirectly related. But who knows.

Thanks for noticing, by the way. This really is a great community of builders all looking out for each other.
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-Joe Wilbur (N520LW)
Phase II - 11/2017
First flight - 8/2017
RV-10 Build Log

Last edited by jwilbur : 05-14-2020 at 07:29 PM.
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  #10  
Old 05-14-2020, 08:26 PM
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RV8JD RV8JD is offline
 
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Quote:
Originally Posted by jwilbur View Post
I replaced the CHT probe. Problem was even worse. Then I rerouted the probe wires away from the plug. So far so good. Compared to the other CHT probes #1 wires were running very close to where the ignition wire enters the plug. Perhaps #1 is electrically noisier due to the other issue. ??

The EGT issue has been exactly the same since first flight. I think the two problems are Probably unrelated or only indirectly related. But who knows.

Thanks for noticing, by the way. This really is a great community of builders all looking out for each other.
Thanks for the follow-up. Glad it's fixed.
__________________
Carl N.
Arlington, WA (KAWO)
RV-8, 790 Tach Hours
(Pic 1),(Pic 2)
- Out with the Old, In with the New
(Pic)
RV-8, 1938 Tach Hours (Pic 1),(Pic 2) - Sold

Glasflugel Standard Libelle 201B - Sold
Rolladen-Schneider LS1-f - No longer owned

Last edited by RV8JD : 05-14-2020 at 08:31 PM.
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