Break in With Air Oil Separator

[mfleming]

Brand new IO-360-M1B.
Lycoming says it’s broke in when the oil consumption stabilizes.

My engine has about 10 hrs on it and has not used an appreciable amount of oil in 5 hours. I was thinking it’s broke in but then I remembered the air oil separator.

Does a new engine, before break in, throw or burn the oil? Seems to me it’s burning the oil but if it throws it, the air oil separator could mask that by returning the oil to the crankcase.

I’d like to fly at lower power setting but don’t want to risk shortchanging the break in.

 

[BillL]

The oil during break-in goes past the rings, so it is burned in the combustion chamber.

BTW - Blow-by is not a primary cause of oil consumption. I was sitting in an engine design group during a year of high oil consumption. Higher pressures than our Lycs. The piston had one compression and one oil ring. The one compression ring yielded higher blow by for this engine and was never linked to oil consumption.

Testing never found "the solution" but I was called to the factory one day for a high consumption teardown of a 1000 hr QC test engine. I looked at the reflection on the face of the oil ring and saw a dashed image on the ring face. That was the root cause. Rings are potted with an abrasive and it was insufficient to make these rings round. One brand/supplier did this and the alternate brand did not. The good brand was adopted and the other had some scrap to replace. Names withheld to protect the guilty.

To be fair the team (I was not on it) did address many other potential causes and really improved quality control, but once this was identified, the problem did not come back.

 

[Tommy123]

Yep, oil getting past the rings and being burned until the rings set.

 

[mfleming]

So it sounds like I can assume my engine is broken in since the oil consumption has stabilized. Sound correct?

 

[Mconner7]

Mike,
I am at 25 hours since overhaul and my oil consumption dropped to almost nothing in the first 10 hours without a separator.