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Join Date: May 2005
Location: Abbotsford BC
Posts: 290
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what is acceptable oil pressure
I am wondering what is acceptable oil pressure on and older 3.0 engine?
What is the min pressures an engine should run at idle warm? |
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01-10-2010, 06:18 PM
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The owners manual says it's acceptable for the oil pressure light to be on at idle when hot. I've seen as low as 5 psi at idle with the engine very hot (240 degrees). Rule of thumb is 10 psi per 1000 RPM. For example: 20 PSI at 2k, 30 PSI at 3k, etc.
-Andy
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72 Carrera RS replica, Spec 911 racer |
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01-10-2010, 08:24 PM
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Join Date: Oct 2008
Location: Nash County, NC.
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If you have the 3.0 in an early car, pre 78 the thing you have to do is match the sending units to the guage both the oil pressure and the temp sending units have to be replaced
Bruce |
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01-11-2010, 05:21 AM
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Join Date: Oct 2006
Location: MYR S.C.
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Quote:
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86 930 94kmiles [_  _] RUNNING:[__] NOT RUNNING: ____77 911S widebody: SOLD88 BMW 325is 200K+ SOLD 03 BMW 330CI 220K:: [_ _] RUNNING: [__] NOT RUNNING:01 suburban 330K:: [_ _] RUNNING: [__] NOT RUNNING:RACE CAR:: sold |
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01-11-2010, 09:42 AM
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They did not change the pumps back for the SC. I thought those numbers were for all 911's up to the 3.2 Carrera. 964's may be different. The numbers I quoted are minimums. My car shows 60 PSI at 40 when hot. I think the original question was what is the minimum acceptable oil pressure.
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72 Carrera RS replica, Spec 911 racer |
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01-11-2010, 09:53 AM
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Join Date: Aug 2005
Location: Atlanta, GA
Posts: 227
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Oil Pressure not above 4 Bar?
Hello, I have an SC with 3.0. The engine was recently rebuilt by a shop that is well regarded on this forum and the Early S Registry. I am still breaking in at about 1,000 miles and just had the oil changed again and tune-up/valve adjustment. The engine is running very well except the oil pressure has me a little stumped. When the engine is warm at 80 C the oil pressure is right at 4 bar at 4,000 rpm, which willl drop only slightly to about 3.7 bar when it heats up to between 95-100 C. However it virtually never goes above 4 bar, especially once it's warm between 80-100 C, it only ranges between about 3.5 bar at 3,000 rpm to 4 bar at 4,200 thru 5,500 rpm. I have not exceeded 5,500 rpm yet, but will soon.
So it seems to have good to factory spec pressure up to 4 bar, but I expected more pressure in the 5,000+ rpm range as with other 911s that I have owned. Any insights? The car has a front loop cooler, and the engine rebuild included a full bottom end with the original 3.0 oil pump. I use Valvoline VR1 20w-50, and live in "Hot"lanta (at least this summer). Thanks for your thoughts. |
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07-29-2010, 03:44 PM
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Join Date: Oct 2003
Location: London Ont Canada
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Best to confirm with a mechanical guage first.. The electric guages are often wrong. Low oil pressure after a rebuild can be caused by excessive clearances either in the bearings or pump. This would likely show up as VERY low pressures at idle and low RPMs, not normal low RPM press then low at higher speed.. You may have a weak pressure relief spring (there are 2). It would allow the pressure to rise with RPMs normally until it reached a certain pressure when it opens and pressure goes no higher
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1980 911 SC 3.6 coupe sold 1995 993 coupe 1966 Mustang Shelby clone 1964 Corvair Spyder Turbo gone 2012 Boss 302 |
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07-31-2010, 05:45 PM
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