High EGT -- Simple Solution

[Darrel Starr]

Lately my four EGT readings (EI Gauge) have been diverging -- #1 remains the coolest, #2 somewhat higher but #3 and #4 slowly creeping up over the last 30 hrs until the spread from coolest to hottest was 200F+ when in the recent past the spread was 80 to 100F. Also #3 and #4 EGTs increased rapidly on takeoff. The EI gauge red light glows when the differential exceeds 195F, so the light was on through the last flight before we started the diagnosis.
My IA, Bob Eckstein, and I checked the primer to make sure it was not leaking internally, we checked the timing (spot on), made sure the impulse coupler was ok, checked compresson, made sure the fine wire plugs were OK (resistance check, cleaned and inspected with a magnifying glass -- all fine.
Then I made an advanced Google search on this subject and turned up this 2003 Supercub.org thread: http://www.supercub.org/forum/archiv...p/t-20372.html
Probes coated with carbon & lead -- so I removed the probes and used a Dremel with a brush and voilá, on the next flight EGTs returned to an 80F spread.
So thanks to a Supercub thread from 8 years ago and an experience shared by "Speedo", we got a big clue that led us to the solution -- thanks Speedy, thanks Supercub.org!
Darrel

[Dave Calkins]

I think Speedo is Diggler. I hope he doesn't delete any more posts.

Thanks for the reminder Darrell. Thanks Speedo. DAVE

[Cubus Maximus]

Would not a simpler remedy be the factory solution? Don't install an EGT...

[StewartB]

Paralysis by analysis? All the classic symptoms including expenditure of unnecessary maintenance dollars. That's never happened to me!

SB

[Darrel Starr]

I know that ignorance is bliss and that many folks believe that having the data is a waste of time. But I am an engineer and devour data, love the stuff, so I disagree. I'll take the most information I can get, all day long.

[StewartB]

Ha! If it was me and I couldn't recognize a trend of varying CHTs to follow the changes in EGTs I'd have pulled the gauge to see what the hell was wrong with the CHT components.

No really. I don't look at that gauge much other than to indicate the engine's warm enough to go. I love the high temp idiot light. I think it was made just for me.

SB

[spinner2]

Darrel, I've had three planes (including my current project) with EI UBG-16's and think they're great instruments that produce useful information. I'm an engineer too and subscribe to the theory that knowing CHT and EGT temps are helpful in leaning ops, especially with a fuel injected engine.

[PA12driver]

push in the little black knob (or the one that screws if you have a modified mixture cable? (just jokin) I have had all that stuff and as been said they are a relative indicator of what is happening (lot of variables, but for sure if it is getting higher it is leaner and and there is a reason for it. (just saying)

[Darrel Starr]

There is a reason unless, as in my case, the lead coated probes were giving an erroneous reading.

[Tim]

PA12driver----------- Now there's a blast from the past. Where've you been Tim