My vessel is on its second Atomic Four - this one a Moyer-rebuilt late model that was installed about two years ago. With both of my engines, I have had extremely limited success in being able to adjust oil pressure using the regulator screw located below the fuel pump. I frequently have to motor for three or four hours or more at a time (cruising RPM usually between 1800 and 2000, boat speed between 4.5 and 5.5 knots), and my experience is that oil pressure starts off the end of the pressure gauge (in excess of 60 psi), then drops for about the first two hours. For most of this season, it's eventually settled at around 20 - 25 psi, with no obvious ill effects. I've been adding a turn to the pressure adjustment screw here and there all season, with virtually no effect. This past weekend, motoring back from the Annapolis area (fortunately passing under the Bay Bridge well before the awful truck accident Sunday morning), oil pressure settled at 20, which, although low, still seemed ok for the short term (still in excess of engine RPM/100), but when we dropped to idle in Bodkin Creek, to lower the main prior to docking, the pressure dropped far enough for our oil pressure safety switch to kill the engine.
I got it started again by quickly bypassing the safety switch with a hotwire, from the battery + terminal to the fuel pump (to the Admiral's great admiration!) and we got back in the slip easily enough. Next day, I said "heck with it" and I screwed in the pressure adjuster several more turns until it was all the way flush with the lock nut, and we took her out for a 2 1/2 hour test run under motor.
This time, the pressure dropped steadily for two hours, this time settling at about 30, and dropping to idle took it down to about 17 - 18 psi (well above half of the cruising level). I'd probably be satisfied if I thought that 30 would be my base cruising oil pressure, but I'm concerned as to why there seems to be such little response in adjusting the oil pressure regulator screw. Don says that a nominal setting is typically with the screw extended about 1/2" beyond the surface of the lock nut.
I had essentially the same experience with the regulator screw on my old engine (originally the ball and spring type - eventually replaced with the older pointed rod type, no improvement), could never get the oil pressure to settle at a comfortable level while cruising, and eventually a bearing gave out - leading to replacement of the engine.
I use SAE 30, high detergent oil, keep it filled between the "add" and "full" marks on the dipstick, change the oil every 50 hours, and generally try to keep the engine well maintained. The only think I haven't tried yet is to dress up the seat on the oil pressure regulator, although it seems early for that, as the engine has been in service for just under two years since rebuild, with about 250 hours of logged use. I have a hard time believing that this could improve oil pressure performance as substantially as I would like, but I could be wrong.
I would welcome any comments or suggestions from Don or anyone else who has had oil pressure issues.
As always, thanks for the help!
Jesse Delanoy
s/v Agape
Baltimore
I got it started again by quickly bypassing the safety switch with a hotwire, from the battery + terminal to the fuel pump (to the Admiral's great admiration!) and we got back in the slip easily enough. Next day, I said "heck with it" and I screwed in the pressure adjuster several more turns until it was all the way flush with the lock nut, and we took her out for a 2 1/2 hour test run under motor.
This time, the pressure dropped steadily for two hours, this time settling at about 30, and dropping to idle took it down to about 17 - 18 psi (well above half of the cruising level). I'd probably be satisfied if I thought that 30 would be my base cruising oil pressure, but I'm concerned as to why there seems to be such little response in adjusting the oil pressure regulator screw. Don says that a nominal setting is typically with the screw extended about 1/2" beyond the surface of the lock nut.
I had essentially the same experience with the regulator screw on my old engine (originally the ball and spring type - eventually replaced with the older pointed rod type, no improvement), could never get the oil pressure to settle at a comfortable level while cruising, and eventually a bearing gave out - leading to replacement of the engine.
I use SAE 30, high detergent oil, keep it filled between the "add" and "full" marks on the dipstick, change the oil every 50 hours, and generally try to keep the engine well maintained. The only think I haven't tried yet is to dress up the seat on the oil pressure regulator, although it seems early for that, as the engine has been in service for just under two years since rebuild, with about 250 hours of logged use. I have a hard time believing that this could improve oil pressure performance as substantially as I would like, but I could be wrong.
I would welcome any comments or suggestions from Don or anyone else who has had oil pressure issues.
As always, thanks for the help!
Jesse Delanoy
s/v Agape
Baltimore
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