Evelyn Ray
Well-Known Member
I have an O-320 that was OH a long time ago and then had a big top overall in 2001. Since that time it only has roughly 450 hours SMOH, and 300 STOH. I noticed the oil pressure goes low when I come back from flying (~20 psi). So I did a lot of checking. The oil pressure gauge matches an external gauge (it is direct pressure), but it did show about 5 psi low difference after the oil was hot. I replaced the spring with a heavy duty spring and new ball in the relief valve. I also reformed the seat as described by Lycoming and lapped it too. I changed the oil and cut open the filter. No metal visible in the filter, but I did sent out for oil analysis. When I first start up, the pressure goes to between 80-90 at idle. On takeoff with the oil temp of 105, it reads as high as 95. in flight I pulled the throttle back to 1500 and it drops to 55-60. When I landed and taxied back it was reading 25 at 800 RPM. The oil pump was replaced at the top overhaul in 2001 and I think it is good based on the pressures that I do get.All on the lower end of the spectrum, but within range. But when I got oil analysis back, it was high in Iron(46.2), Chromium (64.1), and Aluminum (21.6). Copper was elevated at 15.5. The remaining ones (Nickel, Lead, Silicon) are all good. I pulled the bottom plugs, and 2 were fouled with oil and a couple of drops of oil fell out. I did look in the cylinders with a bore scope. I see some scuffing on one, but nothing obvious. I have not performed a compression test yet. I have owned the plane for 1 year and put about ~40 Hours or so on it.
Sorry for the long write up, but wanted to give the background. But now, I am not sure what to do. Is this indicative of needing an overhaul, top overhaul, rings, or?
Thanks,
Bryan
Sorry for the long write up, but wanted to give the background. But now, I am not sure what to do. Is this indicative of needing an overhaul, top overhaul, rings, or?
Thanks,
Bryan
