Oil pressure


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By 56 effie - 17 Years Ago
I recently fitted an oil pressure gauge to my 272 and was surprised at the readings. When started from cold 20celsius it goes to 60 psi at idle. When warmed up 80celsius it is at 45psi at idle and when revved rises to 75psi. I read in another forum that the "wrong oil" filter can give high oil pressure readings, this person had done an oil change on a 5 year old Ford and the oil pressure gauge went off the scale. After changing the filter to a different make the pressure returned to normal.

Could this be the case with my oil pressure?

What is a normal pressure?

By oldcarmark - 17 Years Ago
Hello Effie,Greetings from Canada!The Ford shop manual states oil pressure as 45-50 psi at 2000 rpm(hot).I put a mechanical gauge on mine recently and oil pressure at idle is about 20-25 hot.When I initially start it cold the pressure goes up around 50-60 and drops back to normal in a couple of minutes.Cold oil will be higher presure and I would think thats normal.I remember reading that post on filters.Maybe yours has a similar situation.Try changing the filter to something like a Quakerstate but not a Fram.Hope this helps.
By charliemccraney - 17 Years Ago
Was the problem with filters a high oil pressure? I thought it had something to do with a lack of a check valve and no oil pressure for a couple seconds at startup.

I'm usually at about 25psi at idle and 55psi when cruising.

Your pressure is not out of line. 10psi per 1000rpm is good.

The pump may have been modified to increase the pressure.
By Ted - 17 Years Ago

On the Y, the oil pressure readings are taken after the oil filter which means any restrictions that are present within an oil filter will show up as a reduced oil pressure at the gauge.  But if the bypass valve on the filter is prematurely open, then there is the potential for the gauge to show an increase in pressure.

 

The 272 in my ’55 Customline at 100K+ miles still has 55 lbs oil pressure at cold idle, 70 lbs at a fast cold idle, 25 lbs. at a hot idle, and 50-55 lbs. when hot and cruising in overdrive.  This is with 10W-40 TropArctic oil.  And these oil pressure readings haven’t changed much since rebuilding the engine back in 1990.

 

With the Y oil pump being actually being over-engineered as far as the amount of oil the engine actually requires, then if the internal engine oil clearances are nominally on the tight side, the oil pressure will be also be on the high side or whatever the limit is for the relief spring in the oil pump.  And don't forget the viscosity of the oil that's being used as that's also as big a player in the final oil pressure as the other variables being discussed.