Maintenance and care
... a few short words to care
After every flying day I clean my radial engine with a fully synthetic acid and resin free spray oil, e.g. WD-40 or Rivolta. The oil infiltrates the dirt brilliantly and protects the parts against new dirt, especially around the rocker arms and valve spring. The exhaust valve is particularly dirty because of the valves’ loss lubrication. Clean it without oil, otherwise the dirt is rubbed in and, in the long run, impossible to get out. Even after many years of use, my engines still look almost brand new.
... a few words to maintenance
During the flying season I check the valve clearance about 2-4 times to ensure a powerful and smooth run. With our 18-cylinder radial engine with no less than 36 valves that is quite a challenge and can easily take up a whole afternoon.
I also lubricate the inlet and outlet valves as well as the rocker arm shaft with heat resistant hybrid spray approximately every one to two hours. If neglected, it is possible that the outlet valve gets stuck on the valve cup and does not close properly anymore. It works in the hot exhaust gas stream and therefore has less lubrication. That is why these problems occur very often: cylinder failure, poor starting and uneven running.
The balls on the push rods are lubricated anew approx. every 5 hours of running time with molikote fat. This decreases the friction to a minimum. Some new lobe fat is put into the lobe casing about every 10 hours. To do that I take out the push rod and fill up approx. 2ml of lobe fat with a syringe. That is enough for the next 10 hours. It also reduces the friction. I only exchange the whole lobe fat after about 60 hours of running time.
At the end of the flying season the push rods in the lobe casing get special treatment.
After taking out the push rods, the push rods are pulled. The push rod’s contact point touching the lobe is polished to a high gloss. It reduces the abrasion. Before re-installation, the push rods are dipped into hybrid lubricants. That minimizes the friction in the push rod implementation. After that the push rods are inserted again the valve clearance should be readjusted!
After a thorough visual inspection to check whether everything is really tight and not torn, the next flying season can begin.
The regular maintenance and care pays off after the years. We take care of our engines like that and since 15 years we are flying our engines without disturbances and failures in our Boeing Stearman PT 17.