Lotus Elan

OIL PRESSURE RELIEF VALVE. How is it fitted?

PostPost by: slpj » Sat Nov 11, 2017 6:18 pm

Hi all,

Early pump with paper filter.

I know that sounds like a daft question, how is the relief valve fittted?

There is a hole in the side of the plunger, and I was wondering if it is critical that this be orientated in a particular direction in the pump body.

Just to clarify, I assume that as pressure exceeds the lift off pressure of the spring, the plunger is lifted off it's seat, and oil flows into the plunger, and out of the hole in the side of it, through the pump body and back down the return tube into the sump. This is the hole and plunger I am referring to.

spring_seat-combo-hole-copy.jpg and


Thanks in anticipation.
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PostPost by: 2cams70 » Sun Nov 12, 2017 12:49 am

That's how it works. The "knob" on the end of the plunger locates inside the spring. Similarly on the retainer the raised portion in the middle locates inside the spring. Give it a good clean and polish to remove any gum so it doesn't stick.
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PostPost by: slpj » Sun Nov 12, 2017 10:50 am

Hi there,

Thanks for replying and confirming how I thought it worked.

Can you also help me with how the plunger sits in the pump body, --- with respect to the hole on the side of the plunger? I didn't take enough notice of it's orientation when I took it out to clean it.

As in my white arrowed picture here. -- When inserting the plunger it can be rotated to place the hole in the side of the plunger, in any position in the pump body. Should the plunger should be inserted, so that the hole will be obscured in the pump body? Or doesn't it matter?

arrow-hole.jpg and


Thanks.
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PostPost by: nmauduit » Sun Nov 12, 2017 2:01 pm

oil exit hole location won't mater as the drilling is wider after the guiding reaming end.
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PostPost by: promotor » Sun Nov 12, 2017 2:14 pm

As already mentioned by a previous poster where the hole is doesn't matter as the oil can still escape once the oil pressure - and therefore the plunger - overcomes the spring.

What is of more importance in your oil pump is whether the rotors are within spec in respect of their relationship to each other and also to the inside of the housing as this is what determines whether you have an oil pump that is physically capable of supplying suitable oil pressure or not.

If your pump isn't capable of producing the pressure then it's likely you should be considering fitting a replacement pump.
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PostPost by: slpj » Sun Nov 12, 2017 2:36 pm

" --- drilling is wider after the guiding reaming end. --- "

Ah yes, so it is. A bit daft of me not to realise that. Thanks.

Yep the pump is very much in spec. So I'll give it good clean and polish the plunger and put it back.

Thanks again.
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