Opening up the hangar after the week felt like we were getting into a routine.
Having a busy week before returning to the engine was likely a blessing. I didn’t have time to think about what might or might not be happening.
Finally seeing my family in Chicago for Easter was better late than never.
The aircraft restorer brought in his entire toolbox, towels, and some oil-dry to absorb the mystery oil and anything else falling from the engine compartment.
While he spread the oil-dry beneath the cowling, I opened the top and the side inspection panels with a screwdriver.
With the top of the engine visible, the aircraft restorer used two wrenches to remove the top spark plugs from the cylinders.
Moment of truth, time to see what they look like after their bath.
The soak in mystery oil should remove any surface rust; more serious concerns, such as pitting or gauges, would remain.
We could see the red mystery oil filling about half of the cylinder cavity through the hole where the spark plug had been sitting.
Sticking the tip of the borescope into the spark plug hole, the restorer and I viewed the picture on his phone.
Some areas appeared to be glinting in the camera’s light to which the restorer moved the tip of the borescope to get a better look. There were similar views in other cylinders.
The spark plugs were then put back into the holes to prepare for pushing the oil through the rest of the engine and out of the exhaust tubes sticking out under the bottom of the engine compartment.
To purge the oil from the cylinder, the aircraft restorer advanced the propellor manually by pulling it through. We could hear the scraping of metal on metal coming from somewhere in the engine or prop as the cylinder head advanced and red oil smelling of peppermint drooled out of the exhaust stack.
After my sister finished piddling the oil out, the restorer used his borescope to inspect the remainder of the cylinder.
The area below the demarcation line on the cylinder wall gleamed like it was new; a red ring ran around the cavity’s middle. Some specks glinted from the walls below the ring, indicating pitting.
Ugh.
Better, but not better enough.
We put the spark plug back in its hole and cleaned up for the day before looking at the aircraft books.
300 hours had been put on the engine since overhaul in 2005. A lot of life happened in the past 18 years for both Dad and me, which did not allow for much flying.
More engine work is needed before we can fly again. How much work is the next determination.
Cylinders would need to be overhauled at the very least, known as a top overhaul, with the possibility of a full overhaul depending on what the inside of the engine looks like.
The last two sets of compression indicated during annual inspections indicated at least scores in the 60s, which are passing.
The restorer said as long as the pitting we saw on the cylinders was not too deep, no more than 10 or 15 thousanths, the cylinders should be savable.
We had been talking about having a cylinder or two on hand as they are getting harder to find, but we had not yet gone down that road.
The restorer listed several options for how to proceed but was going to call the shop that had overhauled to see their prices and lead time for cylinders or sending the engine in.
So much for flying this spring.