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On our late model A4 the oil pressure has suddenly gotten erratic. I believe I have an original gauge with an oil line running to the gauge. The pressure dropped to 20 psi at cruise speed and lowered to 15 psi at idle after having held steady at around 40 psi for quite a while. I did adjust the oil pressure valve and actually had the gauge at 80 psi before re-adjusting to around 40 psi. It held at that pressure for a trip but then lowered to 20 psi again. Checking the oil level indicates that the engine is not using a tremendous amount of oil, pretty much the same as it has been for a while. I'm wondering if the adjustment valve needs replacing, Thinking the spring is damaged. Any thoughts will be appreciated.
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big al..I hear that sometimes the spring can get cock-eyed on the ball and cause erratic readings & pressure. I would recommend taking it out completely and cleaning the hole & associated parts and re-installing to see what you get. To pop the ball out of the hole, take the main spark plug wire off the distributor cap so the engine won't start and use the starter for a second or two..the pressure should pop the ball right into your hand (with a sploosh of oil..have a rag handy.)
Are you using a multi-viscosity or single viscosity oil? A single will thin out a bit when the engine warms up, possibly lowering the pressure some too...also how many hours on the oil? Well used oil may also have trouble maintaining pressure for extended periods..
My $0.02
-Shawn
"Holiday" - '89 Alura 35 #109
"Twice Around" - '77 C-30, #511 with original A-4 & MMI manifold - SOLD! (no longer a two boat owner!!)
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Original Oil Pressure Gauge?!?!
Spring for a direct read gauge from a hardware store or plumber's supply, kinda like getting a second opinion.Comment
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Might be just crud getting in and around the spring and ball...as mentioned take it apart and clean it up. Apparently the older engine set up was better the new one...sure sounds like the problem is right there though.Mo
"Odyssey"
1976 C&C 30 MKI
The pessimist complains about the wind.
The optimist expects it to change.
The realist adjusts the sails.
...Sir William Arthur Ward.Comment
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I had a issue last year with mine.
The old spring was collasping, and the more I tighten down, the worse it got.
I bought the Moyer kit that goes back to the "old style" pointed valve and spring and it works so much better than that ball.
I have not had to touch the last adjustment I made when I installed it.
Over a year of use since.Tyring to keep the Bay's Wooden Boat's history from dying off completely.
DanielComment
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Thanks for the input, I did order the Moyer replacement adjusting valve and will replace it as soon as it arrives. We are using 40 weight oil which had worked well in the hot weather, but the pressure now keeps dropping after an adjustment, it stabilizes at 20 psi and drops to 15 psi at idle. The previous adjustment had lasted more than a season. I will get a second pressure gauge to double check the cluster gauge. Tanks again.Comment
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Did you burp the line at the gauge?
There might be an air bubble(s) causing inaccurate readings.
TRUE GRITComment
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Shouldn't matter. Pressure is pressure, regardless of whether its being exerted by a compressible gas or an incompressible liquid.Originally posted by JOHN COOKSON View Post@(^.^)@ Ed
1977 Pearson P-323 "Dolce Vita"
with rebuilt Atomic-4
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I agree Ed. A bubble wont make a much of a diff. Just a tiny lag time. I do bleed my mechanical oil gauges.Comment
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Have had OP issues and I have the "old style" cone adjustment. You may need to dress the seat. There is a tool for this and MMI has it. Product No. - TOOL_05_172 I have had success using a Phillips head screw driver. VERY GENTLY. Dan S/V Marian ClaireComment
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There could also be foreign matter in the line affecting the reading of the gauge.Originally posted by JOHN COOKSON View PostComment
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I received the regulating valve kit and replaced it today, the one in the A4 was the old style with the stem and looked good. I used the old stem to dress the valve seat and assembled the new valve to the engine. At first it produced 80 psi, but I was able to adjust it to just under 40 psi at cruising throttle and around 32 psi at idle. Time will tell if this pressure will hold, worried that the oil pump is wearing out. Thanks again for all the reponses.Comment
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Al,
Does the gauge increase oil pressure when you increase RPM...that is a good indicator. Sometimes oil pressure will drop when you increase RPM and that is an indication of worn bearings.
Just for your information. I have mine set at 38 psi at idle and it's around 42 psi when underway. I also use 15w40 oil and have been doing so for a number of years now...it's wonderful with these engines and I highly recommend it. Oil changes for me are 20-25 hrs and it doesn't use between oil changes...and remains clean.
Just keep an eye on your pressure for a while but your problem is likely fixed.Mo
"Odyssey"
1976 C&C 30 MKI
The pessimist complains about the wind.
The optimist expects it to change.
The realist adjusts the sails.
...Sir William Arthur Ward.Comment
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The oil pump on the A-4 is basically 2 gears. http://www.moyermarine.com/cgi-bin/s...rebuilder.html Mine has seen many,many hours and still functions well. As you posted the pressure did change as you adjusted and that is a good sign. Idle PSI seems a bit high but I could live with those #s. Dan S/V Marian ClaireComment
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The saga continues, as it does with these older sailboats. We are getting a fair amount of oil in the bilge and the only leak I can see is at the oil pressure gauge line connection at the crankcase which seems to be a copper compression type fitting connected to an adapter that is threaded into the crankcase (pipe threads?). I can't tell whether the compression fitting is the only thing leaking or if the oil is leaking around the adapter also. That adapter looks it could be problem to get out. Has anyone replaced these fitiings, I don't see them in the Moyer catalog? Thanks for your help.Comment
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