-
New engine break in
What is the best way to break in a new engine with steel cylinders. I always thought you wanted to baby steel cylinders by running at a lower rpm as much as you could, and run chrome cylinders as hard as you could. Continental motors service bulletin m89-7r1 states in part;
Level flight cruise should be at 75% power with best power or richer mixture for the first hour of operation. The second hour power settings should alternate between 65% and 75% power with the appropriate best power mixture settings.
But it does not say anything about how to operate after the second hour. Does this mean that it doesn't matter? What say you engine overhaulers???
-
1. Have your engine warm before the first start like having it in a heated hangar or use preheat.
2.Preoil the engine, either with a preoiler or pull half the plugs and spin the engine on the starter a moment to get oil pressure.
2. As soon as you start up, keep the revs down to a fast, clean idle, and as soon as you are at operating temp takeoff and fly.
3. Cruise at 75% power, lean as normal, rpm as normal.
4. Make sure you don't overheat the engine, either on the ground or in climb. If you get hot, lower the nose for more airflow or richen the mixture etc.
5. How do you know when it is "broken in" ? It may run a little hot when first run as there is a lot more wear and friction. When temps begin to cool down at the same power, that is a sign of wearing in .
The other sign is that oil consumption which may be high on first run, will begin to drop as the rings seat in.
6. How long? I can't say but some OH or manufactures say to use break in oil, (mineral, defintely not synthetic) for the first 20 hours.
I have watched the run in of a Merlin on a test stand. Mineral oil and starting at fairly low power, probably 25 inches max. The key is to watch coolant and oil temps which will be higher than normal at first. In a fairly short time, maybe 15 min, the temps will cool off and then the power is increased SLOWLY in steps. Finally the last run will be at takeoff power 61 in and 3000 rpm. This whole process may take 2 or 3 hours with cool down as needed, and any leaks or adjustment made as needed. The Merlin develops so much power and such high cylinder pressures that break in happens pretty quickly, but they must be kept cool. Cylinder liners are all steel, no chrome ones.
I am not an engine builder, but have read and talked to several and they seem to agree on this. I know Ram advises using Phillips 20w50 for break in oil.
-
-
1 Attachment(s)
Here are the break in reccomendations that we (Western Skyways) send with every engine that we remanufacture. Hope it helps!
Jason Becker
Western Skyways
-
Check out this thread over on Van's Air Force. Starting with post #6 in that thread, Russel Mahlon (of Mattituck Engine fame) posted some very definitive guidance based upon cylinder type.
http://www.vansairforce.com/communit...ad.php?t=99444
