Morris Minor Owners Club

My oil pressure is 80 at idle and goes up to 100 . When driving the gauge fluctuations 80 to 100 and will stay at 100 for quite some time . The engine was rebuilt buy a engine machine shop about 18 mouths a go but due to problems I have only just got the car on the road. She drivers fine and no horrible noise but I noticed yesterday that the oil cooler has started to weep .I am just wondering if it would be a weak oil pressure spring. Any help would be appreciated.

The oil pressure is ridiculously high. Your oil pressure relief valve could be sticking. Some metal particles from the engine rebuild could be the cause of the sticking.
Remove the oil pressure relief valve and examine the alloy valve for scoring. If scored replace.
If anything you need a weaker spring not a stronger spring.
A good modification is to replace the alloy valve with a ball bearing as that cannot stick.
http://www.minispares.com/product/Class ... o%20search
You may have to shorten the spring slightly to get the oil pressure right.
An adjustable oil pressure valve cap is another way to go.
http://www.minispares.com/product/Class ... |Back%20to
You need to aim for a oil pressure around 60lb at full revs. High oil pressure just saps engine power & can causes the engine to increase in temp.

The oil pressure is ridiculously high. Your oil pressure relief valve could be sticking. Some metal particles from the engine rebuild could be the cause of the sticking.
Remove the oil pressure relief valve and examine the alloy valve for scoring. If scored replace.
If anything you need a weaker spring not a stronger spring.
A good modification is to replace the alloy valve with a ball bearing as that cannot stick.
http://www.minispares.com/product/Class ... o%20search
You may have to shorten the spring slightly to get the oil pressure right.
An adjustable oil pressure valve cap is another way to go.
http://www.minispares.com/product/Class ... |Back%20to
You need to aim for a oil pressure around 60lb at full revs. High oil pressure just saps engine power & can causes the engine to increase in temp.

The engine in Elsie May has been completely rebuilt too and the oil pressure is high, I have been living with it, as she seems healthy otherwise, however I didn't realise this could be the issue either. So thanks Phil. I shall have to pop mine out too.
Best wishes,
Mike.

I fitted one of the ball and spring valves Phil mentioned and had a similar high oil pressure, re-fitted the standard one and we now have 50-60 psi pretty much at all revs and temperatures. I can't remember where I got it from but clearly some of them out there have the wrong length or stiffness of spring, it might be worth checking what you have.

There are at least three different length oil pressure relief valve springs.
It is not uncommon to have to shorten the oil pressure relief valve spring to suit the ball bearing. It is also not uncommon to have to shorten the oil pressure relief valve spring to get the correct oil pressure when using the standard cup valve. It cannot be assumed that the spring you have fitted is going to give the correct oil pressure as there are unknowns such as engine condition to be taken into consideration.
Getting the right oil pressure is the main reason for fitting the adjustable valve but again you have to shorten the spring to get the best results.
If you do shorten the spring put the shortened end away from the ball bearing or cup.