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07-18-2010, 11:18 AM
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Join Date: Feb 2008
Location: Largo, FL
Posts: 1,029
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Just Lost #6
On the RV-10 ----- 80 hrs but it has been squirrley since 60 hrs.
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08-09-2010, 04:05 PM
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Join Date: Mar 2005
Location: Elkhart, Indiana
Posts: 1,186
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Update: After completing my condition inspection over the weekend, I went flying and noted that my #3 EGT was suddenly spiking to over 1500* and then down to 13XX* ... then back over 1500* ... and back down.
Of course, I didn't bother to pull the probes when I had my cowling off, but now I intend to. My initial thought is that it's just a bad connection, and replacing the connector will solve the problem. However, after reviewing this thread, I'll be very surprised if my probe isn't burned to a crisp! Yeah, it's #3.
I'm planning to pull them later this week and see what I find. Stay tuned ...
__________________
Don McNamara
Peoria, AZ
Builder: RV-8 "Smokey"
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08-10-2010, 07:51 AM
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Join Date: Jan 2005
Location: Cincinnati, OH
Posts: 1,558
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Jamie,
My Dynon supplied probe on cylinder #1 indicated the same as yours did, and it happened a few times now, but then returns to normal operation. I pulled the probe out for a look when it happened the first time and the probe looks fine. It's solid and all there. I'll check my other ones today for comparison. That particular probe may be getting ready to come apart, so I'll see. That particular cylinder is my coolest (EGT) and the warmest (CHT). The highest I've seen on that cylinder is about 1320. My probes are mounted 2" down from the cylinder and I have 200 hours on them. When they go for good, I'll get those better quality ones made from inconel.
__________________
SH
RV6/2001 built/sold 2005
RV8 Fastback/2008 built/sold 2015
RV4/bought 2016/sold/2017
RV8/2018 built/Sold(sadly)
RV4/bought 2019 Flying
Cincinnati, OH/KHAO
JAN2020
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08-11-2010, 06:33 AM
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Join Date: Mar 2005
Location: Elkhart, Indiana
Posts: 1,186
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Went to the hangar last night and pulled the cowling. Here's a shot of the #3 probe in place that has been giving bad info ...
I measured the placement of all four probes before doing anything else. The distance from the exhaust flange ranged from 1.25" to 1.6". Apparently, I only read the instructions where it said to place them on straight pipe not curves, and to be careful about getting the spark plugs out, totally ignoring the part about placing them THE SAME DISTANCE FROM THE FLANGES, in the 2"-8" range. Duh.
Anyway, the #3 probe was at 1.25" from the flange and I fully expected to find it burned to a crisp. However, when I pulled it out, it looked like this ...
So, following Mel's suggestion, I cut down a #6 SS screw and plugged the hole, securing it with a SS hose clamp and saftied it. Then, I remounted the EGT probe at exactly 3" ...
I then replaced the connectors, since that was apparently the source of the problem, not a deteriorated probe. I need to go flying now, to make sure that my fix indeed solved the problem, then decide whether to remount the remaining probes 3" from the flanges.
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Don McNamara
Peoria, AZ
Builder: RV-8 "Smokey"
Last edited by N8RV : 08-11-2010 at 06:58 AM.
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08-14-2010, 07:51 AM
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Join Date: Mar 2005
Location: Elkhart, Indiana
Posts: 1,186
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Update:
After remounting the #3 EGT probe at 3" and replacing the connectors, I decided to do the same with the others. All EGT probes are now exactly 3" from the exhaust flange.
I took it up for a test hop and found that the #3 EGT reading is the coldest, but all are cooler. Seeing that there's a significant difference in readings now, I'm tempted to replace ALL connectors and see if the readings are more consistent.
The stranded wire from the probes is pretty fine, and I'll bet getting a solid crimp is darned near impossible. With the new connectors, I doubled-over the wire before crimping. Something to consider when initially installing EGT probes.
__________________
Don McNamara
Peoria, AZ
Builder: RV-8 "Smokey"
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08-15-2010, 04:40 PM
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Join Date: May 2005
Location: Brisbane Australia
Posts: 568
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Quote:
Originally Posted by N8RV
Update:
I took it up for a test hop and found that the #3 EGT reading is the coldest, but all are cooler.
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Hi Don thanks for your input, could you tell me how much cooler the temps are please. Im about to mount my probes, and hope 3 " will work for me.
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Jamie lee
Brisbane, Australia
RV7A - Now Flying.
0-360,carb,catto 3 blade.
VH-XJL
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08-16-2010, 06:03 AM
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Join Date: Mar 2005
Location: Elkhart, Indiana
Posts: 1,186
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Quote:
Originally Posted by Jamie Aust
Hi Don thanks for your input, could you tell me how much cooler the temps are please. Im about to mount my probes, and hope 3 " will work for me.
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Jamie, before I moved the probes the temps were running in the mid-1400* range when leaned to peak. Now, #s 1, 2 and 4 are closer to 1400* and #3 runs around 1350.
My guess is that if I replaced the connectors on the remaining probe leads, the other three readings would drop as well. Just a guess, but I can't think of any reason that only #3 is significantly cooler now since the probes are all at the same distance from the flange.
__________________
Don McNamara
Peoria, AZ
Builder: RV-8 "Smokey"
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08-22-2010, 04:43 AM
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Join Date: May 2008
Location: Brisbane Qld. Aust.
Posts: 2,271
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Quote:
Update: After completing my condition inspection over the weekend, I went flying and noted that my #3 EGT was suddenly spiking to over 1500* and then down to 13XX* ... then back over 1500* ... and back down.
Of course, I didn't bother to pull the probes when I had my cowling off, but now I intend to. My initial thought is that it's just a bad connection, and replacing the connector will solve the problem. However, after reviewing this thread, I'll be very surprised if my probe isn't burned to a crisp! Yeah, it's #3.
I'm planning to pull them later this week and see what I find. Stay tuned ...
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After seeing your photo of the probe, and reading the comments, you do not have a EGT probe or connector issue at all. Well from my reading your comments anyway.
I will bet you a few beers, the problem is spark plugs.
What I suggest you do and if you do not have an all cylinder monitor (I assume you do by the numbers posted) this gets a bit hard, run the endine at say 1200-300 rpm, and lean it aggressively, then switch to one mag, watch the EGT's, they should ALL rise together, then go back....let it all settle and do the other mag, they too should ALL rise.
Do this in flight while running LOP or as lean as you can get. It will uncover which cylinder has a crook plug. The crook plug is causing the random "rising" EGT just the same as when you do the test above, whil running with both mags the cylinder that effectively runs on one at times is the one with the rising and falling EGT.
Now pull all your plugs, have them cleaned and regapped to around 16 tho and pressure tested. Or just clean and gap them yourself. Do this every 100 hrs.
I just did mine today (after 135hrs) and the gaps were up to 20-22 thou not 15-16. Engine is back to smooth again when LOP.
Your D120/180 is your best friend when you learn to understand what it all tells you!
How old are your plugs and when were they serviced last?
DB
PS.....the actual EGT number is almost meaningless, its the trends that matter.
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08-22-2010, 06:30 AM
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Join Date: Oct 2008
Location: Schaumburg, IL
Posts: 2,053
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For the record, My #4 Dynon probe is acting up. Run's normal then drops to zero then back to normal down a couple hundred over and over. My probes are located at 5.5" from the flange and I will report on the results of my troubleshooting when I get to it.
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Tony Phillips
N524AP, RV 9 (tail wheel)
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08-22-2010, 07:45 AM
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Join Date: Sep 2007
Location: WA
Posts: 988
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suspect the connection...
hi Tony, the crimps on the sensor side have been pretty unreliable for me... the solid wire does not hold well unless it is doubled over and i have had to replace the supplied connections on three of the four probes... i used a butt splice rather than the spade connectors.
__________________
Stephen
RV7 powered by a lycoming thunderbolt IO-390
turning a whirlwind HRT prop
with more hours flying than building... 2,430 on the hobbs!
ORCA Flight
Race 771
margarita!
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