OK, I'm cornfused. The pressure relief valve is meant to limit maximum
oil pressure, why would it raise idle pressure (assuming the plunger was
clean, true, no nicks, burrs, etc.)?
That is, the relief valve should be closed withing a few psi of the max.
allowed pressure (granting a few psi "wiggle room"). It should be fully
closed and seated well above the pressure put out by the pump at idle,
so pressure at idle will be determined by pump, bearings, bushings, etc.
Or am I missing something?
bs
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Bob Spidell San Jose, CA bspidell@comcast.net
'67 Austin-Healey 3000 '56 Austin-Healey 100M
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Subject: Re: Oil Pressure Relief Valve Spring (One More Time!)
> Hi Russ,
>
> All springs tend to fatigue a bit over time. It would certainly do no
> harm to replace the spring. The only unknown, is the tension & quality
> of the replacement spring. A simple experiment would be to place a
> spacer under the existing spring. I believe there is room for up to an
> additional .250" long spacer between the spring & it's cap. (Too long A
> spacer will cause spring coil bind & prevent the relief port from
> uncovering to control the pressure.)
>
> Also try to make sure that the plunger & it's seat are clean, free of
> burrs, & actually fully seating. Tapping the plunger into it's seat with
> a wood dowel often helps. More spring pressure can actually improve a
> leaking valve seat & boost idle pressure as well as running pressure.
>
> On my BN2, a .160" spacer gave 25-45psi hot idle - run. A .360 spacer
> gave 40-60 psi hot idle - run. The max cold run pressure does not exceed
> 60. I'm not sure if the .360" spacer would allow full relief valve
> travel on your specific engine, thus the previously mentioned .250"
> spacer limitation. It would be easy to determine if the spacer was too
> long. The cold max pressure would be too high.
>
> Dave Russell
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