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What should the oil pressure be?

S

sscam69

Guest
I took my vette out for a run with the new aluminum Be-Cool radiator and dual electric fans.

She is still running warm. What I got curious about was the oil pressure.

At idle the pressure is 20psi and at cruising rpm (2500) the pressure is 40psi. I drive my dads cargo (Its a 2000 GMC van) van to do deliveries and at idle its at 40 and at cruising at about 60.

I asked for high volume oil pump, I would figure that means high pressure to get that high flow.

Are these readings correct?
What should they be? and at what rpms?

I have a replacement pump already. I bought it a while back. If I have to replace it how do I prime it?

Thanks

Frank
 
C

cmegga

Guest
That seems low. It may be your gauge if your not seeing any other systhems. Does your oil temp get over 230 - 240 ??? If you have lpw pressuare and hight temp on the oil , it may be time for a rebuild on the bottom end. Rod bearings / main bearings or the cam bearings.
 
Joined
May 6, 2002
Messages
129
Location
Simi Valley, CA USA
Corvette
1975 Red on RED Coupe
I got this from Summit Racing. It's interesting:

"Pressure vs. Volume

Pressure is created by the resistance to flow. For example, the water flowing out of a garden hose has relative low pressure, but when you put your finger over the end of the hose, restricting that flow, the pressure within the hose increases and you see the result by increasing the distance the water travels as it leaves the hose. The resistance to oil flow Inside an engine is from the clearances of the bearing and lifter bore. Engines with increased clearances will require greater flow to maintain the same pressure. As the RPM of the engine increases more oil is required. The oil pump selected should be able to flow the volume of oil required to maintain the pressure desired. A relief spring within the pump relieves the pressure when it reaches the desired level. High pressure pumps have a higher pressure relief spring as also do most high volume pumps. The main disadvantage of using a pump with the ability to flow more than required by the engine resulting in this bypass opening is a very small loss of horsepower."

My pressure with stock equipment is 20-30psi at idle and 40 at cruise.
 
C

c4ever

Guest
Same here. 25-30 at idle ( running temp) and 40+ at speed.
 
1

1969D_Floyd

Guest
My '69 reads rather high 60-70 psi at normal (3000 rpm). The local Chevy dealer explained the larger cam installed before I purchased my baby last summer is the cause. Is this reasonable? He said not to be too concerned about it & that low pressure is more concerning than high pressure.

Being overly cautious, I check the oil level before I turn the key.
 
Joined
Jan 1, 2002
Messages
7,246
Location
Washington, Michigan
Corvette
'67 Marina Blue Convertible
Cams in themselves (the lobes) have no effect on oil pressure; however, the mains and rods are fed pressurized oil from the bottom of the cam bearings, so if the cam and cam bearings are new with spec journal-to-bearing clearance, this will tend to increase pressure (due to less oil being lost out of the bearing).

Oil pumps have little to do with oil pressure, which is a function of cam, main, and rod bearing clearances; older engines with larger bearing clearances will show less oil pressure than a newer engine with tighter bearing clearances due to less flow restriction.

Your oil pressure is fine, IMO.
 

Twin_Turbo

Well-known member
Joined
Jan 11, 2001
Messages
618
Location
Enschede, The Netherlands
Corvette
1982 Twin Turbocharged Red/Black
At least 10psi for every 1000rpm.

Too high pressure isn't that much of a problem. The stock design with the relief valve in the pump is rather foolish, it would be better to have the relief at the enf of the oil system. (like the pressure regulator on a fuel system)

Some modern cars now have the relief valve at the end.

Marck
 
W

wolf_walker

Guest
http://www.corvetteactioncenter.com/forums/showthread.php?threadid=12943

Look for my long-winded oil preasure post in that thread.


20psi at idle is alright, not wonderfull, but alright. I wouldnt worry about it right now, even if you put anothr pump in it likely will not increase.

As for priming, you can use an old distributer shaft in a drill to run the pump and prime the system, a good habbit whenever a car sits for an extended period. They also make special tools for it if you want to spend money on a new toy.. :)
 

Twin_Turbo

Well-known member
Joined
Jan 11, 2001
Messages
618
Location
Enschede, The Netherlands
Corvette
1982 Twin Turbocharged Red/Black
If you use an old distributor you must remove or grind off the cam gear.

Marck
 

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