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Oil Pressure


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#1 Down&Out

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Posted 03 April 2012 - 11:06 PM

Hi folks,

Just a question thats been on my mind for a while.

When reading the economy section of vizards book, he states that for economy purposes you should be wanting about 40lb/ft from what i can recall.

This stuck in my mind, because my mini has wayyy higher pressure than that, we're talking 50 - 60lb/ft.

Is there something wrong? something i need to adjust?

Also, a lower pressure might slow the driveshaft seal leak, so its worth an ask.

Ideas?

#2 fattail95

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Posted 03 April 2012 - 11:19 PM

You sure you mean 50/60lb/ft, cause that is about 0.4psi...

#3 Cooperman

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Posted 03 April 2012 - 11:19 PM

Take it you mean 50 to 60 lbs. per sq. inch pressure (or p.s.i. as it's generally known).
The pressure you achieve will depend on several factors:

The oil grade - a Mini should have a good quality 20w50 oil
The R.P.M. the higher the RPM the higher the pressure will be
The temp - the higher the oil temp. the lower the pressure. Ideal oil temp is around the 85 deg C to 95 deg C region
The condition of the oil pump and crankshaft bearings.

Oil pressure has no effect on drive shaft seal leakage as the sump is unpressurised, unless the engine breathers are blocked. Blocked breathers do not effect the indicated pressure on the gauge.

An engine in good condition with the oil hot should have around 25 psi at 1000 rpm, 45 to 50 psi at 3000 to 3500 rpm and 55 to 60 psi at 4000 rpm & over.

#4 Ethel

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Posted 03 April 2012 - 11:20 PM

It won't help with your leak, there's no oil pressure in the sump. You can reduce the maximum oil pressure by shortening the relief valve spring.

#5 Down&Out

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Posted 03 April 2012 - 11:24 PM

Ok thanks so far folks, looks like i better do an oil change and fit a rev counter before i check it properly!

#6 Cooperman

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Posted 04 April 2012 - 01:43 PM

Ok thanks so far folks, looks like i better do an oil change and fit a rev counter before i check it properly!


Don't worry about a high oil pressure, unless it's over 90 psi cold.
As for oil, best use either Castrol Classic 20w50 or the Halfords equivalent 20w50. Don't be misled by anything which says to use a 10x40 - you need a good quality 20w50 in any Mini.

#7 tiger99

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Posted 05 April 2012 - 12:04 AM

You don't need a rev counter, because you don't need to know the speed with great accuracy, just check at fast idle (around 1000 rpm), at cruising speed, and flat out in 4th, and you will not be far wrong.




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