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have just replaced the spring in the pressure relief valve along with the plunger the new spring measures 43mm as does a spare one i have according to my book it should be 40mm this has resulted in quite high oil pressure should i remove the spring and grind it back to 40mm or leave it alone and be thankful

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How high is the high oil pressure when your engine is hot?

Ron

at 2000 its approx 60+psi at3000 its approx 75+psi on start up its 95+psi when engine is at working temp its 50psi@ 850 rpm do you think this is a batch of springs from mosses that have been made the wrong length?

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Is the oil pressure significantly higher than before replacing the spring?

Why did you change it (presumably there was a problem)?

Are you sure it's not the gauge that is at fault, or dirt/grit/grease in the system?

Edited by BrianC
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It is possible you got the uprated spring. This is slightly longer as you mentioned.

You could grind it off,the pressure will drop, but your oil pressure is not disturbing to me. I have about the same values for a couple of years. No problems here.

A worn relieve valve and spring can take the pressure down a lot. A new valve restores this, but keep in mind than the new spring will loosen up, so the pressure will drop slighly over a couple of hundred miles.

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What is a usual oil pressure? Mine sits at 60 odd idle when cold and probs 25ish idle when hot? Obviously goes higher when its being reving.

 

Per the manual ( for the umpteenth time! ) "...45-65 psi @ 2000 rpm when hot ". Note " hot " can take 30-40 minutes of running to realize. Also, idle speeds can vary by a factor of (2) with commensurate pressure readings ( mine is around 20 psi @ 650 rpm vs. 35 psi @ 1000 rpm when hot ). Based on my experience, the value in the manual applies to an engine in good condition, regardless of mileage.

 

I'd second Ron's advice in your case.

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Could I also repeat what I've posted before, within reason the cold oil pressure is not important, even the tickover oil pressure is not all that important, it's the hot oil pressure at speed under load that matters.

Ron

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Remember that the spring does not make the oil pressure go higher. The pump produces the pressure against the resisitance of the bearing clearances and the viscosity of the oil. The spring is adjusted to give you a by-pass pressure and its adjustment should be set to give you about 70 psi when the engine is running and both the engine and oil are cold. When the engine and oil get warm, the pressure would stay at 70 psi for a "new" or "just re-built" engine. Chaps who race TRs have stated that having the by-pass pressure set higher only causes the oil to get hotter than needed by the shearing forces in the oil caused by the high setting.

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phoned mosses today and apparently they do two springs one which is standard@40mm and one@42mm which is uprated my old spring measured 38mm after reading all comments i will leave the uprated one in there. thanks for taking the time to reply any chiltern group watching may see you at brize norton on saturday

bob

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