[Healeys] [Fwd: Oil Pressure Control]

[jim brown]

For what it's worth many cars have used a similar system like Porsche (944s and 
others). They did have a "fix" after many locked up resulting in no pressure. 
The piston looks almost identical to the Healey valves.




________________________________
From: Chris Dimmock <austin.healey at gmail.com>
To: Joe and Lenore Armour <sebring at illawarra.hotkey.net.au>
Cc: Healey <healeys at autox.team.net>
Sent: Fri, October 1, 2010 11:07:12 AM
Subject: Re: [Healeys] [Fwd: Oil Pressure Control]

Ok. I'll post my oil pressure figures. With a bled valve.
The black and white car is due for an oil nad filter change anyway.
Weather permitting.
Me

Sent from my iPhone

On 01/10/2010, at 4:04 PM, Joe and Lenore Armour 
<sebring at illawarra.hotkey.net.au> wrote:

> FWIW  I have never been able to accept that the crude Healey (all BMC for that 
>matter) 'pressure relief' valve, opens and closes that many times per second to 
>manage the oil pressure we see at the gauge. The seat and valve are too poor a 
>fit to be a positive seal and it  does not remain shut until a certain pressure 
>is reached.  The volume of oil that flows thro a restriction, ie bearings and 
>spray holes etc varies with tempreture, engine speed and general condition and 
>bearing clearences.
> 
> May I suggest that our 'relief valves' are flow control valves and apart from 
>when the engine is stopped, the valve is never in the closed position and thus 
>providing a positive shut-off. The spring/valve manages pressure by controlling 
>the volume of oil allowed to by-pass into the sump.If you inspect a valve it 
>usually is a loose fit in the bore and shows signs of having wear on opposite 
>sides at the two ends, an indication that it spends most of its life rocking 
>back and foward in its bore. Usually most of the oil supplied from the pump 
>should be far in excess of the volume that can circulate thro the engine and 
>therefore is continuously being by-passed back into the sump (pan).
> 
> Most hydraulic system start-ups require ALL air to be bled before 
>commissioning.
> 
> Therefore it is most likely the weak spring tension that is allowing too much 
>oil to by-pass when pressures are insufficient with the engine in GOOD condition
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