Oil pressure valve indentification.

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Remyd
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Oil pressure valve indentification.

Post by Remyd »

Good afternoon,

My GT is oil pressure is running high, 60 at idle and 80 when hot and running, close to 100 when cold.
I am planning on changing the valve and spring, i just wanted confirmation on which bolt is the one for the valve on the picture. Top or Bottom?

Thank you in advance,

Remy
Oil releif valve.jpg
Remy Dubois
1971 MGB GT
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Charles Farran
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Re: Oil pressure valve indentification.

Post by Charles Farran »

Hi Remy,
Its the bottom one with the domed head.
When you remove it mark the dome so you can see where the thread starts
to bite without the spring in, as the assembly is a pain to get back in when
working against the strength of the spring to find the "start point"!
Cheers,
Charles
1980 Roadster
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Remyd
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Re: Oil pressure valve indentification.

Post by Remyd »

Hi Charles,

Thank you for confirming which one it was.
I just tried to have a go at undoing it just to see if it would come out easily. Luckily, I managed to find a 1 inch socket and breaker bar but it won't budge. My thinking is to give it a clean and a spray of WD-40 and see if that works. I need to order to replacement parts too.
Remy Dubois
1971 MGB GT
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Charles Farran
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Re: Oil pressure valve indentification.

Post by Charles Farran »

MGBHive have a replacement relief valve & spring kit 12H865BK.
Cheers,Charles
1980 Roadster
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Bumpa
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Re: Oil pressure valve indentification.

Post by Bumpa »

Remyd wrote: Mon Jul 14, 2025 4:08 pm Hi Charles,

Thank you for confirming which one it was.
I just tried to have a go at undoing it just to see if it would come out easily. Luckily, I managed to find a 1 inch socket and breaker bar but it won't budge. My thinking is to give it a clean and a spray of WD-40 and see if that works. I need to order to replacement parts too.
Just to mention that WD-40 is not a penetrating oil, it is a water displacer. Buy a proper penetrating oil spray for best results.
Mike
1969 MGB GTV8 3.9 Conversion. Many classics have passed through my hands but the faithful BGT V8 is the last man standing.
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Remyd
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Re: Oil pressure valve indentification.

Post by Remyd »

Matter resolved,

Taking the spring and valve out was easy, putting the new one in was a PITA!
At least I could access it from the top but it still took quite a few goes and chosen words to get it in.
Oil pressure down from 80 to 60 whilst idling cold and 80 underload.

Thank you again for the advices.
Remy Dubois
1971 MGB GT
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