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Old 03-09-2010, 09:20 PM   #1
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Default stock oil pump relief valve measurements

FWIW I measured the oil pump spring

It exerts 3.55 kgf @ 5 mm of compression
= 40 lbf/in

diameter of piston = 16 mm = 0.4 in^2

pre load of spring at rest = 10mm

piston cracks open with an additional 3.3 mm ... total 13.3mm ... that's 53 psi

each mm of motion is an add'l 4 psi

The piston has a wear mark which suggests a "wide open" position which has an additional 3mm of movement. This is 65 psi.

For every additional 1 mm of shimming, it adds 4 psi.
If you add a 2 mm shim it'll crack open at 61 psi, and it'll be 73 psi at the "wide open" position.
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Old 03-09-2010, 09:30 PM   #2
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Wonderful man. Thanks for that. I placed a 2mm shim in my bypass. I did it knowing the Oil cooler and remote filter will be on soon.
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