I've recently got a new Millennium in the #6 spot (up front, where it receives maximum cooling air flow.) This is on a Continental O-300 A.

Home field conditions are 1570 MSL runway, OAT usually in the mid-70s, and a fairy short strip, so there's a limit to how much power I can afford to carry into short final.

Engine was serviced with break-in mineral oil (Philips). Run up and leak check were all fine, and it's now flown for its first hour with no issues whatsoever. Engine has an aftermarket oil filter, which was changed out for new. Zero metal in old filter.

I've gotten slightly different advice from a couple IAs and A&Ps about best break-in practices, so thought I'd open it up to the BCP experts.

Thanks,

-Denalipilot

Can't say I'm an expert but did have to replace a cylinder on an O-200, which I understand is the same as on the O-300. The mechanic told us to take it up then fly around at cruise for the next 3 hours, basically get things to wear in before beating it up with pattern work.

I think we babied it for the next 10 hours.

Keep it 75% power or above do not baby it, that is the common mistake most people make. Do this for at least five hrs and you will be happy with the results. If your IA has a different opinion find a new one.

Don't do any long steep climbs........keep lots of cooling air flowing thru engine,
and as Mr Scout says........DO NOT BABY IT !
good luck............

I have always been told to keep it cool and run it hard so the rings seat properly. I have done this one time on an 0-320 and again on an 0-520 with success. No steep climbs and once level run top of the green.

Also-

After the first hour of flying I checked it over for oil leaks (none) and exhaust leaks (none). What I did notice was some very light smoke coming off of the cylinder. It looked a lot like when you burn a wood stove after blacking it, or spraying a section of chimney pipe with high-temp paint. I am thinking this is just paint or anodizing byproduct or factory oil film getting baked for the first time.

Any specific recommendations about leaning, or best altitudes to operate at?

Thanks,

-DP

WFO for the next 10-

ECI has some good info in the following link

http://www.google.com/url?sa=t&source=web&cd=9&ved=0CD8QFjAI&url=http%3A%2F%2Fwww.eci.aero%2Fpdf%2FBreakInInstructions.pdf&ei=JPJZTJfHB8L38AaGh5CcCw&usg=AFQjCNFbGixkCJaWwT-ZAyD0pmdGCAhifg&sig2=UD4hha8kcrSisr3BPLFmCQ

denalipilot wrote:I've recently got a new Millennium in the #6 spot (up front, where it receives maximum cooling air flow.) This is on a Continental O-300 A.

Home field conditions are 1570 MSL runway, OAT usually in the mid-70s, and a fairy short strip, so there's a limit to how much power I can afford to carry into short final.

Being in front does not assure maximum cooling. My hottest cylinder is #2 on a O 360 four cylinder. #2 is the front left cylinder. The air comes in the front but the pressure builds from the rear, cooling the rear cylinders first and then pressure backs up toward the front, the air is then forced downward between the cylinders and fins. The first air to move downward between the fins is in the rear where the highest pressure is, then as pressure backs up to the front it forces the air down between the forward cylinders.

I had some trouble shooting done at Tea SD where they have done extensive RV building and skunk worked endless cooling issues. I had too much air exiting the rear of the baffle to my oil cooler lowering the air pressure within the baffle. After partially plugging the exit for the oil cooler the pressure built up from the rear and the front cylinder temp came down.

I had to break mine in during early winter and had to be sure to drive up oil and cylinder temps to keep from glazing the cylinders. You at least will not have to worry about that. You will have to avoid shock cooling from higher altitudes. The following is from the breakin proceedure from my Superior engine manual. This Superior engine is all millenium cylinders and they are iterchangeable with certified engines even though my engine is not certified. It is the same part number.
I apologize for the size of the print.

Ok. I am myself baffled, by trying to put this scanned page up for you. Go my own gallery under dirtstrip at the right and click on the PDF file I loaded till it comes up.

I rebuilt #5 cylinder three times in four years on my C-145 in the 170. I finally got a different cylinder...it was valve problems not ring problems. Each time I replaced the rings, put Phillips 20-50 XC oil back in, did a runup to check for leaks, and flew it around the pattern at 2500 rpm for an hour, checked for leaks again, and then just flew normally. Engine used about a quart of oil about every 7 hrs of tach time. Never had a ring seating problem ( these were steel cylinders and chrome rings). Had 4 cylinders rebuilt on a friend's O-300 with chrome cylinders, put mineral oil in, did a runup to check for leaks, flew it around the patch for an hour at 2500 rpm, checked for leaks, and then flew about 10 hrs on the mineral oil, dropped the oil and filter, and put in Phillips 20-50, a new filter and flew the plane normally.
As has been said before, don't baby the engine, you need to get the temps up to normal operating range. I replaced all four of the cylinders on my Superior engine at 100 hrs because of a factory recall in '07..again used mineral oil, did a runup to check for leaks, then 1 1/2 hrs going round and round the airport to break it in. Ran for 10 hrs with mineral oil, dropped oil and filter and installed new filter and Phillips 20-50. The engine uses about a quart of oil every 14 hrs of tach time..the same as it did before changing the cylinders

After I get my #3 cylinder replaced on my O-470. I was told to fly to Portland for lunch (about a 2.5 hour flight from Boise) Damn near full power there and back. Like Mr Scout said, "don't baby it".

But, I'm going to keep an eye on this thread, too. Be interesting to read what others have to say.