The bypass valve and spring only limit the maximum pressure, they do not
control the pressure at idle (Unless the valve itself is leaking)
Low indicated oil pressure at (hot) idle can be from just a few sources:
worn oil pump
leaky bypass valve
oil pump pickup sucking air
worn main bearings
wrong weight oil / low oil level.
I have never tried the following on a Healey, but if you suspect a leaky
bypass valve, one trick we used to use on MGB and Spriget engines was to
remove the nut that holds the spring and valve. Make sure the valve face is
clean, if in doubt crank the engine to flush the passage way. Reinstall the
valve, and drop a short 1/4X20 bolt inside the spring. Reinstall spring and
nut. The thickness of the bolt head will increase the pressure on the
You should see an increase in cold oil pressure, and if the valve was
leaking, maybe an increase in hot oil pressure.
On Mon, Jul 28, 2008 at 6:40 PM, Alan Seigrist <email@example.com> wrote:
> Jim -
> Oil pressure in all 50s and 60s Austin engines is controlled by the bypass
> valve and spring. You probably just need to replace the spring and that
> will cause your pressure to go up again. I would replace the valve (i.e.
> the plunger) and spring with every rebuild.
> '52 A90
> '53 BN1
> '64 BJ8
> On Mon, Jul 28, 2008 at 11:34 PM, James Shope <firstname.lastname@example.org
> > with it getting hotter and hotter each day here in vegas, i have watched
> > oil pressure drop down to almost zero when idling after the oil has
> > very hot. i suspect the oil pump but i removed the valve cover to check
> > pressure at idle. oil is coming out all of the rockers as normal, and
> > i
> > loosed the oil feed nut on the rocker arm, oil shot out all over my
> > bay
> > at what i considered a very good pressure. any idea what could be the
> > problem. have checked bearings and they are in excellent shape. could
> > be
> > the oil pump or something wrong in the oil distribution system?
> > healeymanjim
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