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
Peter Schauss wrote:
> According to the BMC shop manual:
>
> Spring free length: 2.687" Number of coils: 13
>
> FWIW, the shop manual lists a slightly shorter spring length for the
> BN4/BN6 engines.
>
> HTH, Peter Schauss
>
> -----Original Message----- From: owner-healeys@autox.team.net
> [mailto:owner-healeys@autox.team.net] On Behalf Of Russ Staub Sent:
> Friday, July 22, 2005 2:42 PM To: Healey list Subject: Oil Pressure
> Relief Valve Spring (One More Time!)
> Hi all,
>
> Finally, to the point of my query. After all the removal surgery to
> this point, I remembered my oil pressure has been a bit lower than
> I'd like, and I've always wondered about that pressure relief valve
> under the filter canister. Well, out it came too. My question: Do
> any of you know if there is a specified length for the spring? Mine
> is 2.63" long, fully extended (unloaded). I'm pretty sure it's
> original, and I vaguely remember some comments on the list regarding
> the possibility of losing some of their full length or strength over
> time.
>
> Regards and TIA,
>
> Russ Staub
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