Boy, do I wish I could type better.... First off, loss of prime is a fairly common occurrence in these small Continentals (A- and C- series and O200). There is some significant anecdotal evidence to suggest that the problem is more prevalent or exacerbated by installation of the F&M oil filter adapter. I have never heard a reasonable explanation for this, but there are too many complaints to ignore. Regardless, bottom line, the root cause of the problem is excess clearance in the oil pump that allows oil to drain back into the sump and also makes it more difficult for the pump to draw oil up from the sump.
Notes on Linda's post: Linda apparently has the F&M oil filter adapter. The procedure she describes relates to the adapter, and will not work with engines not so equipped. Also, when Linda refers to the "adapter" in her post she means the oil filter itself. F&M distributes a torque wrench specifically for the oil filter (and most other oil filters found in the aviation piston engine world) that is not adjustable and preset to the correct torque, which is 18 ft-lbs. The whole point of any procedure is to get oil into the pump to seal it and allow it to draw oil from the sump. Other than the oil cooler pad (where the F&M filter adapter is installed), all orifices where oil can be introduced are lower than the passage to the pump outlet, so injecting oil into the pump is an "uphill battle". Interesting musing, off topic... Piper Cubs and other aircraft sans electrical systems, with the -8 engine, hold a small amount of oil in the oil screen housing, which is higher than the pump outlet. Because they sit in the 3 point attitude, the oil stays in the screen housing. Lifting the tail high in the air allows this oil to flow back into the pump, effectively priming it. This procedure only works on the -8 engines, though. So, what to do, especially if you don't have an F&M oil filter adapter? You can inject oil into the back of the oil screen housing, where the oil temperature sensor goes, but you have to get a good enough seal to force the oil uphill into the pump outlet. Ditto the oil pressure gauge port. Smaller and easier to get a seal on, but a lot farther from the pump inlet, in fact, at the very end of the oil galleries. Here's a fairly easy, not too messy procedure that has worked every time for me. What do you need? A wrench to remove the oil pressure line from the engine fitting (3/8"?). A spark plug socket and appropriate hardware to turn it. A torque wrench to reinstall the spark plugs. A 7/16" wrench and a 3/4" wrench to remove the plug wires (sizes from memory, make sure they fit...) A piece of hose or plastic tubing that fits over the breather tube for the engine, 5/8" ID, if I recall, again, confirm, about 4' long. What to do? Install the plastic tube or hose onto the end of the crankcase vent. Unscrew the oil pressure sense line from the fitting on the engine case. Remove all top plugs from the engine. Take precautions to ensure nothing falls into the plug holes. Position yourself where you can reach the starter actuator, and see the oil pressure fitting on the engine case. Put the free end of the plastic tube in your mouth. Blow into the tube and operate the starter motor while watching the oil pressure fitting. The air pressure in the sump will push oil up the pickup tube into the pump. You should see oil coming out the pressure sensor port in 20 seconds or so. If you do not, stop after 30 seconds and allow the starter to cool for 2 minutes. Repeat. I have never had to repeat more than once. As soon as oil comes out of the oil pressure sensor port, you are done. Reconnect the oil line, reinstall the plugs, remove the plastic, tube and go fly. When this gets to be too much of an aggravation, pull the accessory case off and figure out what's wrong with the oil pump. -- John Skyport East www.skyportservices.net
