Re: Pietenpol-List: Continental Overhaul / Low Oil Pressure...
Posted: Sun Oct 16, 2005 8:41 pm
Original Posted By: Jeff Boatright
Jeff,If the oil pressure is ok after starting the engine cold and drops after it warms up, it is possible that bearing clearances are too great and an overhaul may be necessary. Ideally, the oil pressure should go to, say, 30 - 35 psi after starting and stay there even at cruise with a hot engine. At hot idle it may drop off somewhat, but not much, with a healthy engine. The book says 10 psi hot idle minimum but, in my humble opinion, this is pretty low. The A-65 on my Vagabond goes to 35 psi upon startup and stays there, dropping to 30 psi at hot idle on a hot day. I had the crankshaft ground U10. The fit of the new bearings met new parts tolerances. The rear case was in excellent shape and new oil pump gears were installed. After over 340 hours, everything is still the same (Touch wood!).However, you mention that the oil pump loses its prime after a period of idleness. This is often due to a worn oil pump and removal of the rear case will determine the condition of this item. If your luck is better than mine, the oil pump may be the culprit and the rest of your engine will be fine.Sometimes a bit of debris will unseat the oil pressure valve, resulting in low oil pressure. I don't think this is your problem, but it is easy to check, anyway.Your cruise rpm seems low; most A-65's are cruised at about 2150 rpm. Have you checked the accuracy of your tachometer?Good Luck,Graham Hansen (Pietenpol CF-AUN) ________________________________________________________________________________ Date: Sun, 16 Oct 2005 22:08:37 -0400
Jeff,If the oil pressure is ok after starting the engine cold and drops after it warms up, it is possible that bearing clearances are too great and an overhaul may be necessary. Ideally, the oil pressure should go to, say, 30 - 35 psi after starting and stay there even at cruise with a hot engine. At hot idle it may drop off somewhat, but not much, with a healthy engine. The book says 10 psi hot idle minimum but, in my humble opinion, this is pretty low. The A-65 on my Vagabond goes to 35 psi upon startup and stays there, dropping to 30 psi at hot idle on a hot day. I had the crankshaft ground U10. The fit of the new bearings met new parts tolerances. The rear case was in excellent shape and new oil pump gears were installed. After over 340 hours, everything is still the same (Touch wood!).However, you mention that the oil pump loses its prime after a period of idleness. This is often due to a worn oil pump and removal of the rear case will determine the condition of this item. If your luck is better than mine, the oil pump may be the culprit and the rest of your engine will be fine.Sometimes a bit of debris will unseat the oil pressure valve, resulting in low oil pressure. I don't think this is your problem, but it is easy to check, anyway.Your cruise rpm seems low; most A-65's are cruised at about 2150 rpm. Have you checked the accuracy of your tachometer?Good Luck,Graham Hansen (Pietenpol CF-AUN) ________________________________________________________________________________ Date: Sun, 16 Oct 2005 22:08:37 -0400