RobertE Posted March 31, 2013 Report Posted March 31, 2013 I've read pretty much all there is to read on break in procedures. Some reference 50 degree declines in CHT after a cylinder is broken in and others reference 10-20 degree declines. The overhaul shop (Eagle Engines) ran it for 30 minutes in a cell and my A&P for 90 minutes in a test flight. I've since flown it at high power for 9 hours but see no decline in CHT in any cylinder from the first flight. All are at 340-350 at 75% power with OAT of about 12 Celsius. So I can be pretty sure I'm not going to see a 50 degree decline! I've examined the plugs and two cylinders show no oil consumption but two show evidence of it. But the CHTs in all 4 cylinders are similar. Anyone know what this means? Thanks. Quote
M016576 Posted March 31, 2013 Report Posted March 31, 2013 340-350 at 75% power sounds pretty good to me! Quote
aaronk25 Posted March 31, 2013 Report Posted March 31, 2013 Nice temps I'd just fly it. Every engine is a bit different. Quote
bd32322 Posted April 1, 2013 Report Posted April 1, 2013 What engine work did you do? The CHTs were 350 ish even on the test stand? As the cylinders and rings seat, there should be high CHTs first and then they should lower. Doesnt make sense that you do not see a decline. I'll wait for the experts to chime in, but something doesnt seem right. Quote
N601RX Posted April 1, 2013 Report Posted April 1, 2013 Both the engines that I have broken in have had noticeable CHT drops in the 1st hr of operation. It was on the order of 40deg or so. Both these was field overhauls and with only a quick runup to check everything out and check for leaks. After cool down and a good looking over they were cranked up and immediately flow. I suspect the reason you are not seeing the temp drop is because it occurred in the test cell at the overhauler. 1 Quote
jetdriven Posted April 1, 2013 Report Posted April 1, 2013 Our CHT remained hot for about 50 hours, we couldnt close the cowl flaps for the first 20 hours or so. Doing so would send it to 400 degrees pretty quickly. After 60 hours we had stable CHTs. That was a factory engine.  Yours runs nice and cool. I'd fly it and enjoy the cross country time for the first 50 hours to be sure. Quote
Oscar Avalle Posted April 1, 2013 Report Posted April 1, 2013 My CHT remained high for the first 50 hours too. Only now they have started to come down. So I would say that what you have is not bad news... Quote
N601RX Posted April 1, 2013 Report Posted April 1, 2013 Here is the JPI DATA from my break in flight. It was the 1st time the engine had been cranked other than a few minutes the day before to make sure there was no leaks. I think the OAT was around 60 that day. Now at almost 25 hrs my temps and a OAT of 80 this weekend it was still below 320. This on a F model that isn't supposed to cool as well as a J.  I have the Centri-Lub cam and ECI Moly rings, which may or may not be helping any. I'm not sure what the lycoming ring construction is.  The only other other cylinders I've ever broken in were ECI's on a Cessna 150. I also saw a very pronounced temp drop in the 1st 30 to 45 minutes. Quote
butchgilbert Posted April 3, 2013 Report Posted April 3, 2013 A mechanic told me once that CHTs will normally be higher after new cylinders/engine overhaul due to better compression (normally the main reason for an new cylinder/engine overhaul).  I would try to fly it as much as possible, I believe that once you get some real time on the engine you'll see those CHTs drop very gradually. As long as your baffling is in good shape, enjoy it.  IMHO. Quote
N201MKTurbo Posted April 4, 2013 Report Posted April 4, 2013 My experience with break in is that the CHTs stabilize in about two hours. 1 Quote
RobertE Posted April 4, 2013 Author Report Posted April 4, 2013 My experience with break in is that the CHTs stabilize in about two hours. So the fact that my CHTs are all stable and low (340-350) but two of the 4 cylinders are still burning oil isn't a problem? I'd have guessed that both things - cooler temps and no oil burning - would have occurred at once. My concern, obviously, is do I have a couple of glazed cylinders? Quote
N201MKTurbo Posted April 5, 2013 Report Posted April 5, 2013 If the rings didn't seat, it won't really hurt anything. You may burn some oil and may fowl a plug or two but it wont damage anything. Â I would run it for 50 hours or so before I would consider pulling the cylinders for rework. They will likely improve over time. Â What are the compression readings? Quote
RobertE Posted April 5, 2013 Author Report Posted April 5, 2013 If the rings didn't seat, it won't really hurt anything. You may burn some oil and may fowl a plug or two but it wont damage anything.  I would run it for 50 hours or so before I would consider pulling the cylinders for rework. They will likely improve over time.  What are the compression readings? I don't yet know the compression readings. I'll follow your advice and put what will amount to another 35 hours on it (50 in total) before digging deeper. Quote
MB65E Posted April 5, 2013 Report Posted April 5, 2013 Fly it some more, as hard as temps allow. Keep the mineral oil in there. No additives. After the plugs dry up, and compressions are good, then switch to your normal oil of choice. Should notice a decrease when you change to your normal oil. As the mineral oil will cause slightly more friction. I don't think you really have an issue, but I know you want it broken in. Pretty normal so far but possible room to improve. Best. Quote
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