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View Full Version : 912is high EGT, Split


JoeRuscito
09-08-2020, 08:13 AM
Posted in the rotax forums as well...

I've been noticing recently that my number 4 cylinder is reading just a little higher than normal, hovering around 1605-1615 F on climb out. This seems to have crept up over the last few weeks as I hadn't really seen above 1580 F or so before. This is in the normal range I believe and certainly not the max. Normally this only happens during a climb and I can pull back and it goes down of course, but even at 5500 in level flight I'm still around 1595 F on that cylinder. What really gets my attention isn't the temp but the difference between cylinders. The #1 is below the #4 by 110 F sometimes. 1 and 2 are always cooler than 3 and 4 of course but this split seems high. Is this normal? Also is the slowly rising EGT a sign of something I should address?
Delta Whisky
09-08-2020, 08:44 AM
Joe - have you looked for any signs of an intake leak?
JoeRuscito
09-08-2020, 09:04 AM
Nope, wouldn't even know how to go about that. Id love the education. Another point of note as you mention a leak. I do have a very small amount of coolant show up below the #4 head which seems to come from between the fins. I discussed it with Roger Lee and he didn't make it seem concerning but I think its worth mentioning.
jiott
09-08-2020, 01:35 PM
Don't know if this applies to you, but after about 600 hrs my left EGT started reading erratic. I replaced it with a new one and everything went back to normal. Now after about 800 hrs my right EGT (which is still the original one) has started creeping up higher; at first only about 50F higher than the left, but keeps creeping up until now it is about 200F higher. The engine is running fine so I have been ignoring it, but plan to replace it soon. I have heard that it is a good idea to replace all EGTs at the same time because they are life limited and rarely fail instantly, usually a slow death.

How many hours on yours Joe? If they are relatively new the above may not apply.
JoeRuscito
09-09-2020, 04:32 AM
Im at 400 hrs now. Im going to looks super closely for an intake leak, but I will also keep an eye on it and if it keeps rising look at replacing.
109JB
09-09-2020, 06:17 AM
Sync the carbs.
JoeRuscito
09-09-2020, 06:38 AM
Its an IS so no carbs to sync. DW mentioned the possibility of a clogged injector that might make sense.
109JB
09-09-2020, 06:47 AM
Oops, missed the "IS". In that case, swap the injectors around and see if the high EGT follows the injector. If it does, replace.
Dave S
09-09-2020, 10:02 AM
Maybe some of the gang has seen this; however, in case that is not 100% true here is a link to an article by Mike Busch, of savvy aviation fame, regarding interpreting EGT data.

https://www.savvyanalysis.com/articles/egt-myths-debunked
JoeRuscito
09-10-2020, 06:18 AM
Super helpful article. Thanks Dave
Shadowrider
09-13-2020, 08:48 AM
50f I would not be to concerned but would keep monitoring it. My guess it’s more of indication error. 200f and I would be looking into it, even if it runs fine! More than likely a probe but in would be doing a leak down, borescope, and reading plugs.
109JB
09-13-2020, 01:58 PM
Maybe some of the gang has seen this; however, in case that is not 100% true here is a link to an article by Mike Busch, of savvy aviation fame, regarding interpreting EGT data.

https://www.savvyanalysis.com/articles/egt-myths-debunked

The difference with this is that the OP said the EGT split has changed from a previous normal. This is what would be concerning to me. Not the EGT temp itself, but the trend.