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Steve. Have a look at this page. It describes in detail how the oil passes through the little continentals. http://150cessna.tripod.com/oilflow.html One reads there the following sentence: "The oil pressure port for the gauge connection is located in the outside of the case just forward of the left hand arrow. Thus the oil pressure you see on the gauge in the cockpit is the LOWEST pressure in the engine, at the very end of the oil passages. And this is why it takes so long for pressure to build up after starting. If you were to tap a pressure gauge in at the oil temp bulb/oil screen, just downstream from the pump, you would probably find substantially higher oil pressure readings. " The way your engine behaves - no pressure after sitting hot for too long, but after cooling down, good pressure again- I would suspect that the pressure relieve valve might get stuck when the engine sits totally hot, thus no pressure is build up that you can read on your gauge although the oil pump might actually work just fine. The fact that you get good oil pressure again, when the engine sat over night and was allowed to cool down completely, speaks against the "loosing prime" theory. How does the pump get it's prime back by cooling down??? I would look at the pressure relieve valve - it is easy taken apart - and see whether the spring is fine in there and the piston shows no scuffing or what have it. This is of course no guarantee, I am just thinking out loud. It of course could also be something related to the overhaul of the accessory case... The valve and the pump is part of the accessory case - somewhere there lies your trouble. But I know that valve can be trouble - I had a similar thing with the valve sticking occasionally in a cold engine, making the pressure so high that oil started squirting out from the otherwise new and good gaskets. Good luck. Hartmut N3330H ----- Original Message ----- From: "Steve Lewis" <[EMAIL PROTECTED]> To: <[email protected]> Sent: Monday, May 30, 2005 8:16 AM Subject: [COUPERS-TECH] Need help with Loss of oil pressure problem > ----[Please read http://ercoupers.com/disclaimer.htm before following any advice in this forum.]---- > > > I recently had my C85 rebuilt. After the rebuild on three occasions I found > that I start the plane up - the oil pressure is fine. I fly around for an > hour and oil pressure is fine - I land some where and have lunch. After > lunch I restart the engine and the oil pressure is 0!. The oil pressure > does not come up. > It appears that if the plane is allowed to sit overnight the oil > pressure will come up and be normal. Needles to say this is very disturbing > and I am looking for advice. > Here are the facts. In the rebuild the mechanic was concerned about > corrosion in the accessory case but had a company machine it and replaces > it. Hr replaced the gears on the oil pump. We also replaced the oil sump > with an 0200 sump (6 quarts instead of 4 ). I will commonly fly with 5 or > even 4.5 quarts in the sump. > The problem never happened before the engine was rebuild even though > things were loose enough that when the engine was warm the oil pressure at > idle would be in the 5-10 psi range and at cruise would drop into the 20-30 > psi range as the oil warmed. > My mechanic thinks the oil pump is losing prime as the thin, warm oil > leaks out from around the pump. I am not sure but cannot offer any other > explanation. The last tome the problem occurred I had the local mechanics > take off the oil filter and the cover to the old scree on the accessory > case and squirt in oil and nothing happened - leading me to wonder whether > loss of prime is a good explanation. > Oh yes - I have never had problems when I stop for a short time - long > enough to refuel, for instance. It takes a stop of about an hour - enough > for lunch. Once the oil pressure comes up it stays at 40 PSI without a whimper > Any ideas???? > > > > ========================================================================== == == > To leave this forum go to: http://ercoupers.com/lists.htm > Search the archives on http://escribe.com/aviation/coupers-tech/ > > > > ========================================================================== ==== To leave this forum go to: http://ercoupers.com/lists.htm Search the archives on http://escribe.com/aviation/coupers-tech/
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