EGT temps. and differential

by in 912 / 914 Technical Questions 9 years ago

Hi all, I wonder if someone can tell me what is an acceptable EGT differential on a 912 ULS. On one side of the engine EGT reads approx. 1235 F and the other side reads approx. 1470 F. Seems strange to have such a large difference between them but I am no expert. Carbs are balanced and the engine runs smoothly but I noticed this after we installed a brand new exhaust muffler. Could this have anything to do with the problem? Thx. again for any input.
Terry

Re: EGT temps. and differential

by Roger Lee » 9 years ago

Roger Lee

127 5.2k 4.78k

Hi Terry,

That sway too wide spread. Anywhere from 0-80f is more normal and it will vary with throttle position. The 1470F is more normal. Are the EGT probes 100mm or 4" from the cyl.exhaust flange? They must be the same distance and in the the proper place. Is any header wrap touching one, but not the other? Are the EGT probes old? Check and make sure the connections are tight. Unplug them and plug them back in. You can also use on ohm meter to check the probe at its first connection point. If these don't fix the problem swap the probe wires at the first connection and and see if the problem follows the change in side. After you check all of these things and If it doesn't then get a new EGT for the cold side.

Roger Lee
LSRM-A & Rotax Instructor & Rotax IRC
Tucson, AZ Ryan Airfield (KRYN)
520-349-7056 Cell

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Re: EGT temps. and differential

by itemprop='name' » 9 years ago

0 0 0

Thx. Roger, I will try your suggestions.
Thx. again.
Terry

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Re: EGT temps. and differential

by Bobby Kibby » 9 years ago

Bobby Kibby

0 1 0

I recently had a 600 rpm drop shortly after take off with my 912ULS. The engine is installed in my RV-12 which I built and have been flying for 5 years (245 hrs). I have done all the 5 year replacement items including fuel hoses,coolant hoses, carb sockets, sending Carburetors off for 200 hr service and 5-Yr rubber replacement, and Carbs balanced. I landed and could not get over 4,400 rpm WOT. Defueled the premium auto fuel and re-fueled with Av fuel. After running the Av fuel for a few minutes I could get the 5,000+ rpm and launched to my home airfield. I had an intermediate stop due to weather. On run up after intermediate stop I could not get over 4,400 rpm WOT. The following day I removed the carb bowls and weighed the floats.Each pair were under 7 grams. Saw not contamination. Installed floats and carb bowls and got 5,000+ rpm. Flew to home base without any further problems. Have flown 4 flights (2.5 hrs tot) within gliding range of AP without problems. I downloaded my Dynon 180 data file which has the engine data for the initial 0.9 hr flight after changing to Av gas and it indicates a more than 100 deg egt temperature difference for 0.56 hrs of the flight. the max temp diff was 195 deg (1,174 Lt/ 1369 Rt).EGT probes installed per plans. Current test flights show less that 85 deg egt temp difference. Since I have not found a smoking gun I am not sure if my problem has disappeared and I am reluctant to trust the engine. Any comments or suggestions appreciated. Bob Kibby N712BK

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Re: EGT temps. and differential

by Roger Lee » 9 years ago

Roger Lee

127 5.2k 4.78k

Hi Bobby,

I got your email. Just give me a call our discussion may be too long to just type.

Roger Lee
Tucson, AZ
520-574-1080

Roger Lee
LSRM-A & Rotax Instructor & Rotax IRC
Tucson, AZ Ryan Airfield (KRYN)
520-349-7056 Cell

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Mag Off, EGT High	912 / 914 Technical Questions	6
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EGT temps. and differential

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