LETTER TO THE EDITOR
Just read Ask Paul’s post (A puzzling compression problem) and it reminded me of an problem I found several years ago. I had a Lycoming IO-360 180 hp in a Pitts that began to use some oil. It increased gradually from a quart in 15 or 20 hours to 10, then eight, then on one trip it went to about a quart in three to four hours. The compression was good in the low 70s over 80, so thought I must have broken oil rings.
First I pulled a cylinder with a slightly oily plug expecting to hear the tinkle of ring parts on the shop floor, but heard only a click as the oil ring slid out intact. Not until I got to the top ring did I hear the tinkle on the floor: A broken top ring. I pulled all cylinders to find a broken top ring in each. A little concerning, since the only real indication was a rise in oil consumption, not low compression. All top ring groves were worn beyond limits.
If I remember right, it had only about 800 hours SMOH, however a Pitts engine with a fixed pitch prop does live a tough life.
I thank you for your articles and look forward to more.
STEVE SOPER, via e-mail