I have just remembered that you can see this on the pull out page S/3 of
the Austin-Healey 100 Service Manual. This shows the pressure relief
valve with the main flow and 'overflow' in green. However it also shows
a further 'drain' hole behind the valve. It is this hole that I believe
the Service Journal is referring to. I have a gasket in front of me and
this has the 'scalloping' I referred to earlier in a position that would
allow a way through to the sump. Presumably if oil pressure is allowed
to build up behind the relief valve it would not readily open thus
creating a high oil pressure problem.
All the best
>-------- Original Message --------
>Subject: Re: high engine oil pressure/oil sump gasket
>Date: Mon, 23 Jan 2006 07:04:09 -0700
>From: Dave & M <rusd@velocitus.net>
>Reply-To: rusd@velocitus.net
>To: Manuel Formosinho Sanchez <ManuelFS@Emparque.pt>
>References: <ASP-FE11IW7lJDoWuZM002e2d6e@asp-fe11.asp-telepac.local>
>
>Hi Manuel,
>
>To my knowledge, the BN1 has a spring loaded oil pressure relief
>(bypass) piston in the block. The piston, it's spring, & the cap are
>located on the side of the block below the oil filter. The pressure side
>of the pump connects to the block via a oil line from the pump to the
>block. A return line connects from the pressure relief side of the
>regulator to the oil pump inlet screen housing to provide a path for the
>bypassed oil flow. Refitting a sump gasket would not normally block any
>passages.
>
>Anything that restricted the pressure relief, including the return line
>or the relief valve itself would cause high oil pressure. The most
>likely cause would be a sticking pressure relief valve caused by getting
>contamination into the relief piston assembly.
>
>I would remove the relief valve retaining cap, the spring, & the
>plunger, clean the parts, & reassemble. Make sure that the piston moves
>freely in it's bore.
>
>I have attached a drawing of the BN1,2 oil passages which will be
>removed on the list copy of this message.
>
>Regards,
>Dave Russell
>
>Manuel Formosinho Sanchez wrote:
> > After removing and refiting with a new gasket the crank case (oil
>sump) of
> > my 100/4 BN1 the oil pressure jumped to extremely high levels any
>ideas why?
> > Regards
> > Manuel Sanchez
>
>[demime 1.01d removed an attachment of type image/jpeg which had a name
>of BN1 Oil passages.jpg]
>
--
John Harper
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