I can only quibble with one thing: did he really say 'dampen?'
bs
On 10/7/2010 6:27 AM, BJ8 Healeys wrote:
> Hello, Healeyphiles -
>
> Before the thread on the oil pressure relief valve gets too cold, I wanted
> to provide some information I received via communication with an instrument
> engineer at Autometer (http://www.autometer.com) concerning the function of
> the restrictor hole in the oil gauge line and the advisability of "bleeding"
> the air out of the line.
> While this is unlikely to put this issue to bed for all time, I thought it
> would be helpful to have the input from someone who is actually in the
> business of designing instruments.
>
> According to the engineer, restrictor holes are normally built into
> high-pressure sensing gauges to prevent damage due to dumping pressure into
> them all at once. For the restrictor in the relatively low-pressure oil
> line on Healeys, he says it would help to prevent the gauge from registering
> varying oil pressures from the pump at low engine rpms. As far as the need
> to bleed air out of the line, he says it is not necessary. As a matter of
> fact, the line will "re-air" itself each time the engine is shut down due to
> drain-back of the oil into the engine. Combined with the lack of vacuum
> relief, the restrictor hole will help to slow down the drain-back, but if
> the car sits long enough some oil will drain and will be replaced with air.
> At higher engine rpms, any air in the line acts just as a shock absorber and
> will dampen pressure pulses from the pump.
>
> Happy Healeying!
> Steve Byers
> HBJ8L/36666
> BJ8 Registry
> Havelock, NC USA
> _______________________________________________
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Bob Spidell San Jose, CA bspidell@comcast.net
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